Scrubbers DO NOT export Phosphorus

[Garf]

Sorry, just pointing out that skimming does not just remove food, anymore than harvesting half a kilo of algae a week. The anti skimming standpoint (not from you btw) is akin to the anti scrubbing view. Most of the available food (DOCs) has been consumed before it gets skimmed out, hence exported through a different mechanism.

[Ace25]

ok, now I understand where you are coming from. Thanks for the clarification.

I think the conclusion is the title of this thread is false, algae does export phosphates. What is still a mystery is what processes are at play that make that happen, and what percentage those processes aid in phosphate removal.

As an example with completely made up numbers, 50% of to total phosphates within exported algae are taken in directly via the algae for growth, 40% comes from a symbiotic relationship with proper bacteria strains, and the remaining 10% comes from the filtering effect of the algae catching detritus. In that made up scenario it may be possible to not have the correct bacteria symbiosis which in turn could make the scrubber 40% less efficient.

[Amphiprion]

Nor are abiotic factors taken into consideration, such as localized high pH, which would promote phosphate precipitation. The precipitates cling to the algae to an extent, thus allowing even more export. I haven't seen in situ studies or observations confirming this, but it is an effect that Adey originally proposed could technically occur in and around the turf. Something else to think about, anyway.

[Garf]

Nor are abiotic factors taken into consideration, such as localized high pH, which would promote phosphate precipitation. The precipitates cling to the algae to an extent, thus allowing even more export. I haven't seen in situ studies or observations confirming this, but it is an effect that Adey originally proposed could technically occur in and around the turf. Something else to think about, anyway.

Well, that makes sense. It also throws up another conundrum. From a bit of research I did on blue light and algae, it appeared (to me anyway) that blue light induced an acid production response, to release co2 from carbonate it was assumed. Would this also release any phosphate bound up in the precipitate, therefore reducing the total amount of phos harvested from a screen. Ie red lights only could increase the total phos removed whist harvesting?

[xerophyte_nyc]

"Algal growth, ordinarily phosphorus limited, depends inversely on bacterial phosphorus utilization and growth. We envision phytoplankton and bacterioplankton dynamics as being tightly coupled: both should respond in a similar fashion to trophic variations and in an inverse manner to allochthonous carbon supplies. Although this scheme will undoubtedly prove to be oversimplified (see Cole 1982), we consider it to be a workable starting point for predicting algal and bacterial interactions in situ."


Nice study discussing the tightly-coupled phosphorus sharing between bacteria and algae. They rely on each other. They can be considered as indicators of trophic level. Lots of phosphate = lots of bacteria = lots of algae. As long as algae is present, phosphates are high. ATS = high phosphates. It can't be any other way. If ATS was exporting phosphates then it wouldn't support itself. Catch 22. Unless you see the algae growth on an ATS getting weaker and less on a week to week basis, how could it be exporting phosphate?

A comparison of the abilities of freshwater algae and bacteria to acquire and retain phosphorus

[xerophyte_nyc]

Nor are abiotic factors taken into consideration, such as localized high pH, which would promote phosphate precipitation. The precipitates cling to the algae to an extent, thus allowing even more export. I haven't seen in situ studies or observations confirming this, but it is an effect that Adey originally proposed could technically occur in and around the turf. Something else to think about, anyway.

Also I have seen it mentioned that the ATS is very good at physically trapping detritus. But this potential trapping, and phosphate clinging, are somewhat negated by the fact these particles are sitting there and decomposing before being physically removed.

I think that cleaning the turf screen more regularly could lead to a significant improvement in results. You are removing trapped detritus more often before it deteriorates, and you are removing algae at a time further from when it starts to decay and release more Po into the water. There is also the aspect of removing bacterial biomass which grows together with algae on the screen. I know its more work but it would seem twice weekly screen cleaning could be better than weekly.

[xerophyte_nyc]

Well, that makes sense. It also throws up another conundrum. From a bit of research I did on blue light and algae, it appeared (to me anyway) that blue light induced an acid production response, to release co2 from carbonate it was assumed. Would this also release any phosphate bound up in the precipitate, therefore reducing the total amount of phos harvested from a screen. Ie red lights only could increase the total phos removed whist harvesting?

I think on a screen it wouldn't matter because there is no calcium source on it. I think the breakdown of calcium-phosphate bonds happens in proximity of the acid source. This would impact algae growing on live rock. Another example of how algae and bacteria work hand in hand. Algae helps bacteria nearby by making acid to liberate more Po, which the bacteria use to give the algae more Pi.

[Bilk]

Scrubbers are utilized on a large scale in the Everglades and in other coastal marsh areas to control and remove phosphorus runoff from farming. I think if anyone wants to really understand how these work and what processes are taking place, they should contact Ecological Systems or some other entity. I'm sure they would be willing to share their data or explain the process. I don't have that level of understanding of biology or chemistry so I'll leave this to others. However I think there's a lot of bad science being tossed about here. Not an attack on anyone. Just an observation. Taking bits of information from various sources and trying to piece them together isn't very scientific. As I said, turf scrubbers wouldn't be utilized on a commercial level for water purification and land management, if they weren't effective or if they were contributing more to the problem of managing phosphorus runoff. JMO of course

[Ace25]

One more variable I have always wondered about.. the screen material itself. It is plastic.. bacteria eats plastics.. so does the screen act as sort of a 'bio pellet'? I believe so. Run a screen for over 12 months and see how brittle the screens become. Yes, plastics will become brittle over time but that is normally caused by UV deteriorating the plastic, which I don't have in my ATS environments. As soft as the plastic is on the screen and how quickly it seems to become brittle I do think bacteria is consuming some of it for the carbon source. On my systems any screen over 12 months old (which is the recommended replacement time for a screen anyway) I can clean the algae off and then if I wanted I could crumble the screen into tiny bits and pieces in my hand due to how brittle it is.

[sabbath]

Well I'm used to watching coral reactions to changes that I make. As I just switched from running the Full Zeovit system 3 Months ago. I can tell when things are off and when I need to add aminos or strip the nutrients more. It usually takes a few days to a week to see after making a change.
While on my last couple of months on zeo I stopped all of the algae control methods. Because I wanted to try a ATS and have it deal with the algae part. Long story short, It did not work for me to run zeo with a ATS. So there is a good question for you. Why didn't it work? Anyway I stopped zeo and could not fathom not running a skimmer. As I have had one on my old 125g reef from the early 80's.

So I went;
Skimmer
ATS
Rox 8 Carbon in a reactor(1/2 cup in a 140g system)

This was too much striping of the water. I was starting to lose LPS corals. I pulled the Skimmer (uff) and the coral decline stopped. I ran this way for about a month and all was good with the corals and their colors. The algae is still on a slow decline. I now run the same amount of carbon in a filter bag passively( in a baffle) in the sump. All is still looking good at this point. Corals still not coming back from the over stripping. So I just started today to add a little amino's and see how things react.

So for now this is what is keeping things going in the right direction for me;
ATS
No Skimmer
Rox 8 (1/2 cup passive)
Light Amino dosing
10% month WC

So may I ask how is possible to run a skimmer with a scrubber? I would not have any LPS and not sure about the SPS. Because I stopped before it may have hurt them.