cyano scrubber? ...and also, mud

[34cygni]

Hi, everyone. Long time no see.

I've had phosphorous on my mind for a while, now, and I've come up with a notion or two that might be of interest in these parts. As before, apologies if what I'm pondering has already been pondered, but I do like to geek on this stuff...

I strongly believe the LED gurus are on to something with their recognition of the need to provide a broader spectrum to facilitate bacterial photosynthesis. More on this later, but first, here's my take on the P problem...

I suspect the root of the problem is that we're trying to pull P out of our systems using organisms that are "P-lite" -- that is, the N:P ratio in the algal cells is higher than the Redfield ratio of 16:1 (...which, it should be recalled, is the average N:P ratio of all the stuff scooped up by plankton nets and is most likely not the N:P ratio that would be found by sampling any particular species, or any particular cell, of bacteria or algae). This makes sense in that cyano dominates at low N:P ratios (like 10:1 and below) while green algae outcompetes cyano for P at high N:P ratios (above 20:1). In other words, the problem is the scrubber itself in that it creates an environment so favorable to green algae that it can outcompete cyano even under conditions (low N:P ratio) that should strongly favor cyano. But even so, it's still just green algae, so it simply can't absorb P fast enough to keep up with what's going into the system.

Put simply, if the food going into a system is around 16:1 N:P, then algae with an internal N:P ratio of 18:1 or 20:1 or even higher (see Redfield Ratio is not always 16:1 in phytoplankton (http://algaescrubber.net/forums/showthread.php?2198-Redfield-Ratio-is-not-always-16-1-in-phytoplankton&p=25042#post25042)) can't possibly keep up. It N-limits itself.

The obvious solution here is to dose N, like the FW guys who practice estimative index dosing, but I would argue that dosing macronutrients in a reef tank is inherently risky. To err is human, after all. Besides, from what I've read around here, that doesn't seem to work... My guess is that the problem isn't a micronutrient deficiency; rather, the problem is that not just the algae but the entire microbial loop is starved for nitrogen, and because bacteria are much, much better than algae at capturing nutrients during times of surplus and storing them for future use, that's where most of the N ends up.

So like I said, seems to me the LED guys are on to something with the idea of including bacteria-friendly wavelengths -- if you can't beat 'em, join 'em... I'm thinking, though, that maybe we, as algae-friendly folk, should be looking beyond the display tank to consider the lighting needs of cyanobacteria.

I'm thinking that perhaps what's called for here is a cyano scrubber. Cyano totally hearts low N:P ratios to begin with, so why fight it? The tinkerers and LED guys out there (Floyd, I'm looking in your direction...) may want to consider two-stage scrubbers, with a "normal" scrubber emptying into a low-flow area (maybe even just a sump) that's lit to foster the growth of cyano after N zeros out, or perhaps building scrubbers that can be transitioned from high flow and lighting for green algae to low flow and lighting that's optimized for cyano.

But until somebody figures out whether or not we're all going to have to become cyano farmers, too, as a stopgap solution for P accumulation, I've been considering plumbing a "remote deep mud bed" in a five-gallon plastic bucket into my system. I've been running an algae scrubber since Day 1 and because my DT is small, I don't feed heavily lest my corals outgrow their happy home, so my P levels are still quite low, but "low" isn't undetectable... I can see the writing on the wall at this point.

The reason I've got mud on my mind is that in an anaerobic environment, chemical conditions change such that bacteria can reduce P compounds to orthophosphate (PO4) which persists in the absence of oxygen and, being readily soluble, accumulates to concentrations far higher than what's detectable in the overlying water. Orthophosphate likes to adhere directly to mineral surfaces, so the optimal nutrient sink for P should combine anaerobic reducing conditions with a lot of available surface area per unit volume -- ie, a small grain size, like fine sand or mud... So it's no surprise that "Miracle Mud" and similar products are out there -- not only are they better simulations of the seafloor than pool filter sand, but they're excellent nutrient sinks, as well.

But I'm looking for an inexpensive alternative -- has anyone ever tested river clay from the local art store for P loading? -- because my idea is to let the new mud bed cycle and come into equilibrium with the rest of the system, and then dump it, along with any benthic organisms that managed to colonize it (...just more nutrients to export!), and start over with fresh material. Obviously, I'll never zero out P this way, but P should migrate -- very slowly, over the course of months -- from the established substrate into the RDMB; that is, phosphorous will gradually diffuse out of the area of high concentration and into the area of low concentration. I'm not really worried about P accumulation in my substrate yet, but if you are, this might be worth trying, as it's simple, comparatively cheap, and very low maintenance.

The basic idea is that much like a scrubber establishes a "sweet spot" in the system where the environment is optimal for the growth of green algae, a remote deep mud bed would be a sweet spot where phosphorous will want to accumulate. And like an algae scrubber, it has to be cleaned regularly to be effective... Happily, "regularly" in this context probably means something on the order of once or twice a year. Like I said: low maintenance.

[SantaMonica]

cyano dominates at low N:P ratios (like 10:1 and below) while green algae outcompetes cyano for P at high N:P ratios (above 20:1)

Where do you find this research?

[34cygni]

This is old hat (http://www.thekrib.com/Plants/Algae/cyanobacteria.html#16). It predates the interwebs, so it turns up in textbooks and is pretty much taken for granted -- like the ocean's food web being dominated by bacteria, not algae.

The 10:1 and 20:1 ratios absolutely should not be taken as gospel, BTW; it's more like 10:1 and 22:1 (http://mralgae.blogspot.com/2009/02/redfield-ratio.html). I just put up ballpark figures from memory meant to emphasize that as the system's nutrient balance drifts away from 16:1, conditions will inevitably come to favor either cyano or green algae (...or diatoms if Si levels are high).

And be sure to follow the link at the bottom of Mr. Algae's page (http://buddendo.home.xs4all.nl/aquarium/redfield_eng.htm).

[SantaMonica]

I know about bacteria; I meant the ratios.

I'm sure the Chuck fellow means well, with the two tanks they tested, and the "it seems to indicate", but I was more referring to actual research on the ratios and biology such as found in journals that do thousands of tests...

Reefbase.org
Int-res.com/site-service/search
data.aims.gov.au
plankt.oxfordjournals.org/content/by/year
tos.org/oceanography/issues/archive.html
terrapub.co.jp
aslo.org/lo/search.html
bioone.org/search/advanced
www.aoml.noaa.gov/general/lib/CREWS/
bioone.org/loi/jnbs
jstor.org/action/showPublication?journalCode=jnortamerbentsoc
springerlink.com/content/100407
springerlink.com/content/100441
onlinelibrary.wiley.com/journal/10.1111/(ISSN)1529-8817/issues

[34cygni]

First off, SM, I must respectfully note that you're declining to address my actual thesis, which is that green algae with an N:P ratio higher than the N:P of the food going into an aquarium cannot possibly remove all the P without supplemental nitrogen. This seems intuitively obvious, and it troubles me. Is the N:P ratio of the algae in the scrubber known to be lower than 16:1? Aren't bacteria typically P-heavy and algae P-lite, relative to the Redfield ratio? Can you establish that I have erred by presuming that scrubber algae is, like most algaes other than cyano, P-lite? Failure is the road to wisdom, sir, so I beg you to please explain my mistakes and perhaps even join me as I ponder and seek to correct them.

But if you want real science and hard numbers, I respect that. Here you go (http://www.plantedaquariums.co.uk/index.php?option=com_content&view=article&id=162&Itemid=69).

Here's a cut'n'paste of the salient bit:

--

The nitrogen : Phosphorus ratio as a factor regulating phytoplankton community structure : Nutrient ratios
(by: BULGAKOV N. G. and LEVICH A. P. ; Moscow State University 1999.)

ABSTRACT: Shifts in phytoplankton species composition following changes in N: P ratio have been observed in artificial laboratory microcosms and natural phytoplankton communities in vitro and in situ. The experiments reported and reviewed here have shown that high N: P weight ratios (20-50: 1) can favor the development of Chlorococcales, while a reduction of the N: P ratio to values of 5 to 10 frequently leads to a community dominated by Cyanophyta. Model calculations predict that the relative abundance of different phytoplankton species depends only on the relative amounts of N and P in the environment, so that the optimal N: P ratio for a given species is equal to the ratio of its minimum cell requirements for these elements. An empirical test of this hypothesis showed that for several species of Chlorococcales and Cyanophyta the ratios of their cellular requirements for N and P determined experimentally were close to their optimal (for growth) environmental concentration ratios. For instance, an experimental increase in the N: P ratio from a value of 4:1 to 25-50: 1 by mass in the water of fish-breeding ponds led to an increased abundance of Chlorococcales. The species shift was due mainly to Scenedesmus quadricauda, which has a high optimal N: P ratio for growth.

--

Emphasis is mine, not the original author's. Like I said, this is old hat.

I've learned to avoid citing references like that in online forums, as most hobbyists want "real world" examples of how things work in other people's aquariums -- Mr. Algae carries more weight than Dr. Levich, I'm afraid. Changing minds requires citing respected hobbyists, not respected scientists, but like you, I take science as my starting point.



I'm sure the Chuck fellow means well, with the two tanks they tested, and the "it seems to indicate"

Mockery is an invitation to others to laugh along with you in order to validate the position you've taken, and seeking validation telegraphs weakness, not strength. More saliently, if it is your wish to maintain a civil and evidence-based discourse, I suggest you lead by example. Marshall your thoughts, state your case, and provide functioning links that lead to specific documents that either support your position or erode mine.

[Garf]

34cygni - have you read this stuff. Seems like we agree on the function of dominance at least.
http://algaescrubber.net/forums/showthread.php?2095-Dinoflagellates&p=24767&viewfull=1#post24767

[34cygni]

If you've been puzzling over cyano's relationship to P accumulation in the substrate, Garf, you may find this interesting (http://www.pnwmas.org/forums/showthread.php?31036-Cyano-bactiria&p=300357&viewfull=1#post300357). Be sure to mouse around over the text -- there are several links in there, but they don't show up as blue underlined text for all users. Something peculiar to the board, I believe.

As for this...


This may not only apply to this topic but others where nutrient skewed effects are noticed. The algae requiring LOWEST nutrients become dominant. Therefore algae doing the LEAST filtering become dominant.

There are other variables in play than simply nutrients, but yes, I broadly agree. As Dr. Levich noted, algae with an internal nutrient ratio close to the N:P ratio in the water will do best -- not the "least filtering" algae, but I think that's what you meant by "LOWEST nutrients": the algae that had the fewest leftovers.

However, selection pressures in a scrubber are unique and they seem to be strong enough to maintain a population of green algae even when N is very low and the N:P ratio should strongly favor cyano. I wonder if the biggest variable in the selection process is actually the weekly cleaning, as it's well known that the activities of grazing animals have a profound impact on the composition of a local algae population. Basically, the stuff that the grazers don't eat takes over.

Cleaning a scrubber screen is some pretty hardcore grazing, if you will... The algae that sticks up won't get hammered down, but it will get scraped off. But on the other hand, it only happens once a week. Weird selection pressure. I don't know what that might do beyond select for algae that grabs onto the plastic really well.

My best guess is that it's a combination of that, the lighting, and the very high flow conditions in a scrubber that keep the scrubber algae competitive. In particular, the high flow both within a reef tank and through the scrubber turns over the entire water column through the scrubber quickly enough to give the scrubber algae first crack at the good stuff. That, at any rate, seems to me like the only way it could manage to outcompete cyano even after N zeroes out.



I will probably take a bit of beating over this but if this theory is correct then nitrate limited screens probably started out as high ratio screens which then became PHOSPHATE limited. This starved out the normal ratio algae and low nitrate : phos ratio algae took over the screen. This new algae could use more nitrate than phos, leading into a skewing of the filtration balance leaving more phos in the water column. This low ratio algae could also assimilate ammonia faster to supplement the nitrate limitation that it has caused. Hence the rise in phos..

There may be a period when a scrubber is first attached to a mature system and you're getting lush, thick, dark growth, that a P-heavy algae is growing, but I suspect N limitation is the inevitable result of a scrubber based on green algae, and the system never becomes P-limited. The water may be depleted of P at times as heavy algae growth sucks in nutrients, but my thinking is that the scrubber will eventually zero out N, and the system will begin to accumulate P again.

[Garf]

Good read in that link. That's exactly the impression that I have been given after reading all the scientific stuff I could find on the subject. I find it amusing that he was totally ignored and people just carried on dumping stuff in their tanks.

[Floyd R Turbo]

34cygni, great info, thanks for posting. What a great thought to battle cyano with cyano, or to use it to combat the P problem.

This thread seems to be also a subset of this conversation http://algaescrubber.net/forums/showthread.php?2173-Phosphate-that-won-t-go-away and you support my contention that this purported mechanism cannot explain rising P, which as you put it, is inevitable.

It is wise to also note that the algae scrubber is not the only filtration system that experiences this - check out this product site and blurb:

http://www.po4x4.com/Site/


Maintaining the levels of waste products low while feeding your animals on a regular basis is essential for keeping invertebrates and fish in good health. In microbial well balanced aquaria, the two major pollutants are nitrates and phosphates. With current use of NP-Reducing BioPellets, it has become very easy to maintain nitrates and phosphate levels close to zero, however, in most tanks there is still a surplus of phosphates. Phosphate levels exceeding 0.03 ppm will negatively affect coral growth and higher levels will also negatively influence the health of your fish. In addition, high phosphate levels enhance the growth of annoying algae and cyanobacteria. Most of current phosphate reducing products are based on granular ferric hydroxide and leak iron-ions into your tank, which is enhancing algae growth and inhibiting coral growth and have a tendency to start clumping together, thus reducing its effectiveness.

emphasis mine.

[34cygni]

Good read in that link. That's exactly the impression that I have been given after reading all the scientific stuff I could find on the subject. I find it amusing that he was totally ignored and people just carried on dumping stuff in their tanks.

In the interest of full disclosure, I'm Totoro. The Pacific NW Marine Aquarium Society is the local SW fish club, and they're kind enough to tolerate my little lectures as I think through this stuff. And like I said, I've learned to stop quoting scientists... hobbyists, as you observed, generally don't dig that stuff.

BTW, I think my analysis of EI dosing at the end of that post is wrong. I had just discovered Mr. Algae's page that day while I was googling for links to support what I had written, and I didn't read it closely enough to pick up on the "Buddy Ratio". I gather that's what you're supposed to use with the numbers from test kits (...obviously, I am not a graduate of the Redfield Ratio School of Algae Management).

Still works, though: EI recommends NO3 from 5-30 ppm and PO4 from 1-3 ppm (http://www.barrreport.com/showthread.php/62-The-Estimative-Index-of-Dosing-or-No-Need-for-Test-Kits), so the upper bounds of the system (which I gather is where the cool kids hang out) perfectly correspond with the ideal Buddy Ratio of 10:1. Neat! Assuming "average" levels of 17.5 ppm NO3 and 2 ppm PO4, that's a Buddy Ratio of 8.75. Only at the low end does it go beyond the recommended Buddy Ratio range of 7:1 to 13:1. Either way, it appears that Mr. Barr empirically discovered how to manage algae by maintaining his tanks within the 10:1 to 22:1 window instead of reasoning his way there, but you can't argue with results -- especially considering that he got there first.



What a great thought to battle cyano with cyano, or to use it to combat the P problem.

Biogeochemical cycling is what I find most interesting about the hobby -- which is to say, it's not that I'm so smart, it's just that I'm the lone oceanographer in a room full of marine biologists. But to give credit where it's due, it was IIRC a post somewhere in this thread (http://algaescrubber.net/forums/showthread.php?2173-Phosphate-that-won-t-go-away&) about somebody having a bit of success bringing down P with intermittent skimming that was the trigger. I don't lurk here, but I do check in occasionally to see what you guys are up to, so I just saw that thread for the first time the other day... and intermittent skimming seemed interesting because bacteria are normally P-heavy, so if you let the population build up, and perhaps also have the good fortune to catch the skimmable fraction of bacteria at or near high points in their various boom-and-bust cycles, it seems plausible that you could remove a detectable amount of phosphorous. Then I thought, "Sure would be nice if there was some way to cultivate enough bacteria to do the job without turning the DT into bacteria soup."

And then my head exploded. And then I felt like an absolute idiot for not having thought of it earlier, which to my mind is a pretty reliable test for the quality of an idea.

Don't know if it'll actually work, but I'm just a theoretician, so I'm handing it off to the experimentalists so you guys can play with it.



in most tanks there is still a surplus of phosphates

I know many, perhaps even most hobbyists are skeptical about "Old Tank Syndrome (http://www.beananimal.com/articles/old-tank-syndrome.aspx)" and the "DSB nutrient time bomb", but not only do I take phosphorous accumulation in the substrate for granted, I believe it is the key to the Standard Model (http://en.wikipedia.org/wiki/Standard_Model) of Aquarium Algae -- which I've been too chicken to post and instead kind of snuck onto the table to see if anyone would notice:


as the system's nutrient balance drifts away from 16:1, conditions will inevitably come to favor either cyano or green algae (...or diatoms if Si levels are high)

So I guess I may as well pull the trigger...

Let's start by reviewing algae in the natural world.

It's well established that "typical" (the word being in quotes because, of course, there's no such thing...) freshwater temperate lakes experience an annual cycle of algae: in the spring, there's a diatom bloom; as the water warms, there's a green algae bloom; in mid-to-late summer, cyano takes over and remains the dominant form of algae until winter knocks back all primary production. The same pattern -- diatoms, green algae, and then cyano -- also occurs in tropical lakes, but there's no winter to reset the clock, so once cyano takes over, that's all she wrote.

Sound familiar?

Adriaan Briene, the Redfield ratio guy (http://buddendo.home.xs4all.nl/aquarium/redfield_eng.htm), got that the balance between cyano and green algae -- which is usually a phyto bloom in the wild, BTW, rather than green nuisance algae -- is governed by the N:P ratio. Most experienced hobbyists take for granted that low N favors cyano because it can fix its own nitrogen, and low N generally means low N:P ratio; green algaes must obtain their N from the water and cannot outcompete cyano for P unless there's enough N floating around, so high N:P ratios favor green algae.

The missing piece of the puzzle is the Si:P ratio, because as far as diatoms are concerned, dissolved silica is a macronutrient. If you're curious, the diatomaceous Redfield ratio (actually the Redfield-Brzezinski ratio) is 106:16:15:1 -- that's C:N:Si:P.

In a newly established aquarium, P levels are extremely low (though maybe not so much if you're using live rock or live sand from an established tank), so the N:P ratio will remain high for some time. This means green algae has the advantage, but diatoms will outcompete green algae for P at high Si:P ratios, so if there's any dissolved silica in the system -- not uncommon if unRODIed tap water is used for the initial fill before cycling -- then you'll get a diatom bloom.

The diatoms will quickly deplete the system of Si (unless you keep adding more from the tap during top offs or water changes (http://www.pnwmas.org/forums/showthread.php?33508-Suggestions-on-a-Canister-Filter/page4&highlight=tapwater+diatom+bloom)) and get eaten, 'cause everybody loves diatoms. This opens the door to green algae. Some aquarists do actually experience a greenwater phase, but most of us get green nuisance algae. This can potentially last for quite a while -- FOWLR and FW hobbyists, in particular, can tolerate rather high nitrate levels that keep the N:P ratio favorable to green algae.

But eventually, P accumulating in the substrate will tip the balance to favor cyano. Cyano, however, is vulnerable to antibiotics, and hobbyists often kill it off, thereby opening the door to weird, P-loving, and very likely P-heavy algaes like BBA (http://aquariumalgae.blogspot.com/2006/06/black-beard-algae-bba-red-brush-algae.html) that were once consigned to obscure ecological niches but now plague hobbyists worldwide.

So while the progression of algae types both in the wild and in aquaria is governed by P ratios, what changes these nutrient ratios to favor first one type of algae and then another is a bit different. In the wild, P ratios change by nutrient depletion: at high N:P and high Si:P, diatoms can bloom and will then draw down dissolved Si until they lose their competitive advantage over green algae; at high N:P and low Si:P, green algae can bloom and will then draw down N until it loses its competitive advantage over cyano; and then cyano goes to town. Diatoms will also go away in aquaria as a result of consuming Si until they can no longer bloom, but the transition from green algae to cyano is governed by P accumulation gradually lowering the N:P ratio, rather than N dropping because it's being consumed by primary producers. Though of course, very low or zero N is achievable with an ATS or in a heavily planted FW tank...

I believe in this mental model because it is consistent with the available science and it has tremendous explanatory power, being able to account for decades of observations by hobbyists, a recent innovation in FW planted tank management, and the BBA plague in FW tanks, among other things. However, I acknowledge that it is only a crude sketch of a hugely complex and nuanced system -- as I said, I think this is the Standard Model of Aquarium Algae, not the Grand Unified Theory of Aquarium Algae.

A true GUT would have to incorporate a host of variables I can't begin to account for. To be sure, P ratios are in the driver's seat when it comes to the competition between diatoms, green algae, and cyano, but what outcompetes what involves temperature, pH, lighting, flow, the presence or absence of grazers, and a host of imponderables ranging from dynamic ones like micronutrient ratios and unseen boom-and-bust population cycles in the microbial loop to "fixed variables" such as the actual cell sizes of the various algae species that are present in an aquarium (...because small algae cells have a high surface area-to-volume ratio and absorb nutrients from the water more efficiently, but large cells have more surface area, so they're able to capture more light).

Algae scrubbers demonstrate that it's possible to push these secondary selection pressures so hard that you can actually override the governing N:P ratio, which is something the experimentalists should keep in the back of their minds as they explore the fringes of the hobby.

And one final note: the Redfield ratio is a global average of a population average. A real oceanographer -- which I assure you, I am not -- would tell you that the Redfield ratio doesn't drive algae populations; rather, the local algae population drives the Redfield ratio (http://www.atmos.ucla.edu/~cdeutsch/papers/weber_deutsch_nat_10.pdf).

[Ace25]

Wow.. in the words of Wayne and Garth .. "We're not worthy!". So much great information, thank you so much for posting!

[Garf]

Right, what's the plan for the cyano scrubber ? A screen or sand bed lit by a 350nm light source ?

http://algaescrubber.net/forums/showthread.php?2169-Skimmers-help-Scrubbers-breathe&p=24524&viewfull=1#post24524

[34cygni]

So much great information, thank you so much for posting!

If you find the information useful or the Standard Model plausible, please direct the attention of others to it. I don't get out much.



Right, what's the plan for the cyano scrubber ? A screen or sand bed lit by a 350nm light source ?

I like the cut of your jib, Garf.

Cyano wants to grow on old substrates that have absorbed plenty of P, so letting it grow there and seeing if you can cultivate enough to bring down P seems like an obvious starting point.

Note that cyano can recruit diatoms into a microbial mat. Because diatoms like high N:P rations, my guess is that the cyano is the dominant partner in that symbiosis and keeps the diatoms N-limited most of the time, just like coral keeps its algal symbionts N-limited to force them to pump out sugar that the coral eats. Cyano will have a much easier time recruiting diatoms on a substrate of silica sand than on aragonite or white sand composed of pulverized coral, as the anoxic layer beneath a microbial mat permits dissolved Si to diffuse out of the sand along with P, Fe, and other nutrients with low solubility in oxygenated water. In terms of the overall functioning of a cyano scrubber, I really don't know whether encouraging it to recruit diatoms is a Good Thing or a Bad Thing... It seems like it should be a Good Thing, as more algal biomass = more nutrient export capacity, but the presence of diatoms could screw up a two-stage scrubber by competing against the green algae for N. The experimentalists may want to try it both ways to compare and contrast the results.

But to make a cyano scrubber practical, it can't involve disturbing the substrate in a tank or sump. People don't generally like doing anything that can affect water clarity, so it'll probably have to end up in its own little space like a regular scrubber. That's why I was thinking of two-stage scrubbers with one high-flow chamber to sustain a green algae scrubber and one low-flow chamber to permit the growth of cyano, or a "tunable" scrubber that can be optimized for either green algae or cyano.

I like the idea of a two-stage scrubber, with a green algae scrubber overflowing or draining into a cyano scrubber. I suspect the latter is preferable to directing the overflow from a green algae waterfall scrubber into a cyano scrubber because (1) the drainage from an N-limited scrubber releasing sugars from photosynthesis should encourage growth by feeding the cyano DOC that it would normally be getting from captive diatoms, and (2) cyano has a reputation for coming and going on its own if you leave it alone. My thinking is that in an aquarium, a cyano bloom eventually pulls enough P out of the substrate to lose its competitive advantage and dies back, and then P starts accumulating again until conditions are right for another bloom. Something similar might happen in a cyano scrubber, with the cyano coming and going in waves as P is drained from the scrubber substrate and then builds back up as it diffuses out of the tank substrate. If that's how it works, we may want to regularly turn the lights off in the cyano scrubber to encourage P accumulation, and either way, we'll need the green algae scrubber to prevent nutrient spikes when the cyano isn't growing.

And frankly, what happens if somebody actually manages to get a system close to zeroing out both N and P is a mystery to me, so it makes sense to keep all options open to see which algae ends up dominant when there are no measurable macronutrients present, or if the cyano and green algae can achieve peaceful coexistence.

Also, it might be worth taking another look at the first generation, pre-SantaMonica scrubber configuration, when it was basically a horizontal trough filled with rocks. The rocks may provide a "good enough" P sink to cultivate cyano on them without any fine particles that could be stirred up and cloud the water when they're removed for cleaning.



http://algaescrubber.net/forums/show...ll=1#post24524

Followed your link. I'll let you guys worry about the light spectrum, but I did notice this at the top of the page with the diagram you linked to:


Does this pose answers to any of the current UAS symptoms, where surfactants may be getting concentrated on the screen algae ( causing brown stuff )?

Can you point me to some pix of UAS algae with "brown stuff" on it? My ATS is an old waterfall design, so I haven't been paying much attention to the new design, but "brown stuff" sounds like it could be something I'm familiar with from what might be called an "upflow java moss scrubber" I have in a FW tank, so it's possible that I've already cobbled together a theory to explain this...

For the record, my UJMS predates my awareness of the UAS, as suggested by a post in this old thread (http://algaescrubber.net/forums/archive/index.php/t-1284.html):


I've long suspected that one of the advantages enjoyed by filamentous and brush algae is that they trap drifting detritus in their strands, and by virtue of proximity and the dynamics (or lack thereof) in the boundary layer, the algae gets first crack at the nutrients released from decaying detritus. Java moss seems to follow this design philosophy, as well, even to the extent of providing habitat to recruit small animals that groom the moss and eat the tasty bits, thereby speeding along the process of their decay.

[RkyRickstr]

Guys alot of useful info that i will never understand.. but i have a quick question.. wouldnt it be so much easier to run a bit of gfo as needed?

[Garf]

Guys alot of useful info that i will never understand.. but i have a quick question.. wouldnt it be so much easier to run a bit of gfo as needed?

Probably easier, yes.

[34cygni]

wouldnt it be so much easier to run a bit of gfo as needed?

The name of the game is bioremediation. If you're satisfied controlling P through chemical means, I'm not going to tell you you're wrong, but please understand that from my perspective, that method is philosophically unsatisfactory. It's also energy-intensive (I'm speaking more of the manufacturing process than the implementation) which expands the carbon footprint of a hobby that's already pretty resource-intensive, and from a more practical standpoint, it can get pricey over the long haul.

Plus, as Floyd pointed out, even the manufacturers acknowledge in the fine print that chemical scrubbing is more about controlling P in the water column than mitigating P accumulation in the substrate.

[Doompie]

I recently had a discussion with a micro biologist (funny fact I found later: the inventor of biopellets) , he also more or less brought up this subject.. after some exchange of ideas, he came with this: Build one (small) scrubber next to the algae one which you light 24h..

Don't know, might be a one to think about..

[Garf]

Oh yes indeed. Cheers Doompie.

[RkyRickstr]

I gotcha.. is there an article on best conditions for cyano.. ill try it.

[34cygni]

I recently had a discussion with a micro biologist (funny fact I found later: the inventor of biopellets) , he also more or less brought up this subject..

Thanks very much for chiming in, Doompie. Even if it's secondhand and anecdotal, it's good to have confirmation that there's more to this than a crackpot hobbyist coming out of nowhere with a plan to save the world from phosphorous.



I gotcha.. is there an article on best conditions for cyano.. ill try it.

I think we're off the edge of the map, here, but try this (http://www.biodesign.asu.edu/news/benchtop-biofuels-fine-tuning-growth-conditions-helps-cyanobacteria-flourish).

Further information I just retrieved from one of my books that will be important to the experimentalists: cyano needs Fe in a big way because the enzymes involved in fixing nitrogen are known to be very iron-rich, and growth using N2 as a nitrogen source can require as much as 10x more Fe than autotrophic growth using NH3 to supply N. Autotrophic growth on nitrate also requires iron-rich enzymes to convert NO3 to NH3, BTW, but less so than cyano.

Thus, even moreso than with a green algae scrubber, regular iron dosing will be necessary to sustain a cyano scrubber.

[kaskiles]

Someone recently posted success with a cyano scrubber on rc, thread 2229534, in the Advanced Topics. It's a balled up wad of plastic screen, used to keep fish from jumping out of open top, placed in the DT...

[iiluisii]

how about making a horizontal type scrubber with no angle just straight horizontal and using a piece of white egg crate as a screen running a low flow though it and then using old t5 bulbs to light it to encourage cyano. one thing i notice about white egg crate is that cyano love it

[SantaMonica]

If you want cyano, just reduce the wattage on your scrubber lights.

[Garf]

If you read the Allelopathy thread, this may not be the way to go;
http://algaescrubber.net/forums/showthread.php?2321-Marine-Allelopathy
There is some evidence that some of the compounds released May give cyano an advantage in the rest of the system.