View Full Version : Questions after 10 months scrubbing

08-22-2009, 02:20 AM
I've been running a skimmerless reef with a scrubber successfully for 10 months now. I have experimented as I went along, and would like to question some of the accepted methods used. I realise that often things that happen are specific to ones own system, and would therefore like to hear what others have to add to my observations.

The biggest discrepancy I have is that I feel that the screen only really kicks in after there is a weeks worth of growth on it. It seems that less water runs over the algae, but rather through it, once it is denser. This continues for up to 3 weeks of growth, when it really does become high time to scrape the screen as light penetration becomes an issue. I grow the screens between 2-3 weeks and have never had an issue of the lower levels of algae dieing and releasing posphates back into the system.

Pods eating algae? It has never once been an issue on my screens. If they do eat it, they have never left any holes in the screen. Which brings me to my last point. Why on earth would we want to clean our screens in fresh water? This sets the algae growth back by 24-48hrs in my estimation. I'm gaugeing this on the oxygen bubbles that form amongst the photosynthesising algae. It take 2 days before I see any bubbles after a fresh water cleaning. After rinsing in saltwater, there are bubbles present within hours again. Pods are present in the scrubber area all of the time, and move around very rapidly, so rinsing the screen in fresh water does not help, as new one will jump right back on as soon as the screen is replaced. Anyhow, the large ones that could possible eat enough algae to cause an issue(and I doubt this) have already been scraped away with the algae.

I'm currently experimenting with optimum lighting periods on the screens and will post on this once I have results. I want to see if 18hr on/ 6hr off is the ideal period, or if the algae continues useing nutrients in the dark phase as well, and where a 12 on/12/off cycle wouldn't be better.

08-22-2009, 12:59 PM
Thanks for the observations!

I would tend to collaborate your findings. I have had zero pod issues even with a huge pod loading in the tank - really huge. I have never found pods to care about any macro algae. They are very persnickety. They even have major preferences. Greatly preferring red micro algae to green micro algae.

Real ocean turf gets fresh water rinses. I have done many FW rinses (with chlorine) and never seen any obvious inhibition. I will admit to never seeing any bubbles form because I never expected to see any in the furious surface flow.

Are there any pics of your scrubber about?
Do you have any close ups of the flow/bubbles?

08-22-2009, 01:39 PM
Good observations. All have been thought of and tested to various extents by other folks here and there, but the current recommendations were established to help most of the people most of the time (especially first-time scrubber users). As you mention, certain tanks will have variations, like yours (especially after maturing), and when you get enough experience, it may help to alter things.

The number one problem that occurs with most new users on every site is building the scrubber and then just letting it "sit" until it "looks full of algae". And by algae, they mean "nice fluffy green stuff". Scrubbers rarely start out green, and certainly don't get thick and full in the first cleaning period. So what has to be avoided, is letting the beginners think "it just needs more time to turn green and thick". Because if they wait, the pods kick in, the bottom layers kick in, and then they end up with cloudy colored water, and worse nutrients than when they started. I've seen it hundreds of times. Happens on every site.

Your scrubber has a few particulars which make it different from most: Very strong lighting, and very good flow. Here is how that alters things:

Growth time: In your case, the strong flow and lighting cause very rapid growth of the top/new layers. So yes you get good filtering for more than one week, because just as the bottom layers are starting to slow down/die, you have three fresh new layers to make up for it. But most people don't have such strong lighting, and possibly also their pipes get clogged quicker (so less flow too). So they won't get the rapid new top layers to make up for the dying bottom layers. (My scrubber will go longer than a week too, but I'm running 100W on a screen that is just 5 inches tall, and just 1 inch away, so the rapid growth outpaces the dying layers.)

Another big pitfall is systems with high nutrients (which is most tanks with a new scrubber). These tanks grow the dark/oily stuff to begin with, which only gets to be 1/8 inch thick or so at best. Bottom layers start dying in just a few days, because all light is cut off. So if let to "grow" for a few weeks, it's a certain failure. So by making sure the screen is cleaned every 7 days, you eliminate problems in all of the the under-lit, under-flow, and/or oily-growth scrubbers. And this is why everyone who runs their scrubbers under the 7-day recommendation get good results. Not stellar results, like yours, but good. In your case, since you know what to look for, and you know how to tell if your nutrients are rising or falling, you are in a safe place to experiment, ESPECIALLY since you began your scrubber last year using the basic recommendations.

Pods: The original recommendation of using FW came from Inland Aquatics, who had been running scrubbers for ten years previous. So I started with that. This, combined with the fact that you need to remove the screen and clean it somewhere besides the tank, led to the FW-in-the-sink recommendation. Everyone has a sink, so it works good. But as for the effects of pods, remember that they are in the algae for a reason: To eat it. This eating starts out small, with just a few thousand white specs (baby pods) scattered across the screen. They are only eating a little, but the rapid new growth on the the top layers more than makes up for it. After a few days, however, there are millions of pods, and this is when they consume enough algae to out-pace the new growth of the average scrubber. You don't "see" any of this though, because each pod's effect is invisible; it's just evenly spread throughout the algae. It's not until the last stage of pod growth, where they multiply in groups/colonies/localized areas, that visible "holes" are found. And even this is only visible when it's actually on the screen; if it's "in the algae", then it just get covered by other algae. Indeed, I've seen many new scrubber users baffled when their scrubbers don't work; and when they post pics, there are 3" round holes of bare screen, and they say "It's had 4 weeks to grow already, and it's still not working."

So, we're back to your high-powered new growth greatly out-pacing the effects of the pods. It just so happens that your particular scrubber takes three weeks before the effects catch up. For the average scrubber, it's much sooner. And this is again the reason for the 7-day cleaning recommendation; it works for everyone. And the FW makes sure that the groups/colonies/localized areas are wiped out.

Lighting: Many people complain of having to run a single 23W bulb, much less two of them (much less 4 X 45W that you have.) So the 7-day FW rule keeps thier pod and die-off effects from overcoming their (slow) new growth. And this is on top of them having flow problems. And as for the OFF period, 18/6 is actually not the best, it's just the easiest. The "best" is 3 X 2hrs OFF, or 6 X 1hr OFF. Studies (non-scrubber related) have been done to confirm this. Turns out that most of the respiration that is occuring in the OFF period actually happens at the very beginning of the period, and trails off from there. So most effective is to keep it short, more often. But of course for the typical new user, especially those with bedroom or living room tanks where you can see the scrubber light, this can't be done.

Anyways, experimenters will experiment, and that's why scrubbers are here in the first place, so it will be nice to see what specific things help your system perform better.

08-23-2009, 02:27 AM
Thanks SM for the detailing.

08-23-2009, 10:55 PM
Thanks again for all of your effort Santa Monica. Without your perseverance, I would never have ventured down this road. Your explanations clear up any questions I had.

08-24-2009, 06:48 PM
I thought that the pulsing flow had a lot to due with the usage of light? I see now that SM says it isn't worth the time to put a scrubber on a pulsed flow. I read in dynamic aquaria that the pulsing of the flow acts as a light flasher. Which goes hand in hand with small ammounts of light more often.

08-25-2009, 01:07 AM
And as for the OFF period, 18/6 is actually not the best, it's just the easiest. The "best" is 3 X 2hrs OFF, or 6 X 1hr OFF. Studies (non-scrubber related) have been done to confirm this. Turns out that most of the respiration that is occuring in the OFF period actually happens at the very beginning of the period, and trails off from there. So most effective is to keep it short, more often.
Do you have a link where I could read up on this, so that I can optimalise the experiment that I'm performing? I'd like to use the intervals as you describe, weighing the dried harvest over an 8 week period. I'll then use the 18/6 period as the control for a further 8 weeks. Do you see any room for improving the experiment? I'm starting with new lights, and will keep feeding as even as possible, obviously not adding any new livestock or changing any other parameters.

08-25-2009, 02:49 AM
I would say that you should change nothing for 2 weeks then do a 4 week study. Then change your light period to whatever, and then wait 2 weeks to allow any physiological changes needed by the turf to align with the new lighting, before the next 4 week study. If you just change it the turf may stumble for a week before adapting to the new light and this would skew your results.

08-25-2009, 07:24 AM
wait 2 weeks to allow any physiological changes needed by the turf to align with the new lighting,
Thanks kcress. I have to do that anyway as I have a 2 screen scrubber. I think though that any new algae would be instantly "aligned" to the new light provided. I would think that the only thing that a particular species of algae may expect would be the usual daylight pattern, light intensity and spectrum of it's natural environment. It would be interesting to hear from any horticulturists out there if the plants do develop some sort of "memory" regarding light period.

08-25-2009, 10:44 AM
I'll try to find it. I ran across it before I started keeping track of research.

08-25-2009, 03:03 PM
If there's one thing I've learned about in marine ecosystems, it's that there are so many different competing organisms that something as small as a lighting change can move an entirely different species up to the leading role. I would not assume the same turf would necessarily even remain.

08-26-2009, 05:07 AM
Here is a link to a very interesting finding http://www3.interscience.wiley.com/jour ... 7/abstract (http://www3.interscience.wiley.com/journal/118502527/abstract)
It seems that in certain brown intertidal algae, the nitrate reductase activity was not limited by light/dark cycles as submersion does not always coincide with daylight! This opens a whole new can of worms. Do most intertidal algae species conform to this pattern? Or should we be looking for ones that do? Logic tells me that all intertidal species woulds have to follow this pattern to some degree.

The problem is "planting" these algae on our screens is not going to be easy. Would they need a dry, or semi-dry period?

08-26-2009, 08:36 AM
Well you found something quicker than I did. Unfortunately I did not save the pdf of the study I mentioned, but I is probably in the Phycology journal somewhere.

08-27-2009, 06:15 PM
So, no one has a comment on what I posted earlier?

As it was just proved by borders link. Think back to the very Turff this whole thing (ATS, aka, Scrubbers) was started on. It grows on piers and rocks and the such and it grows after being exposed to tidal shifts of hours. Also like it was mentioned, light doesn't always coinside with submersion. Perhaps, this is why Turff is more efficent then HA is.

Sorry for the sarcastic feeling but......Like it says under my name...I am slime algae.WTH.

08-27-2009, 07:31 PM
The reason pulsed flow is not recommend has nothing to do with light... it has to do with complexity, and contact time. Plus, nobody has ever tested pulsed-vs-non-pulsed side by side. But those who have built surges do not show any greater growth than non-surges.

08-27-2009, 08:49 PM
I am not trying to hijack this thread here, I do think it is pertaining to the findings here. If others don't then I will leave happily.

Well I am confused.
How can Turff be better at what is does and live naturally where and how it does, and not benifit from a duplication of its enviroment? I do agree that a pulsed flow engauges in a more complex build for somone. It also takes up more space. Turff grows where HA doesn't. The link posted is in reference to brown algaes and growing during periods of no light as well as dry pieriods.

Have you read Dynamic Aquaria? I am sure you have, I think I remember you referencing it some time ago. It is stated in there about pulsed flow acting as a light flasher. The light absorbstion is more eiffecent when submersed, then when it is not. I wonder if that is why those algaes exposed to dry pieriods have adapted to not needing light.

Contact time.....Yea it is less. I think directly of teeth on an overflow. It gives half the flow compaired to its length. In this case, the algae is only getting about half the water run over it. Also, the pulsing flow might only be a problem on these new vertical style. The original was the tip dump style. Which woul be a more turbulant puddle verses a stream of water. It is know that a straight on stream creates a turbulant area around an object creating less flow directly on the surface of that object.(A low pressure zone) That is why folks want a wave maker in thier tank to create a changing flow patteren, or a heck of a lot of flow to get it counter acting itself. Getting rid of such a zone around thier corals or algae. Water pumping into a bucket will be turbulient, then it dumps, starting all over again.I can't think of anyone who showed more growth on thier screens as sly. He has a pulsed flow. I last talked with him he had to shut it down because it was growing so much it plugged up the plumbing. Who is growing as much as or more than sly? I am not a member of as many forums as you are.

I should mention that since the little spots of Turff showed up on my screen and have now almost covered half of it.....my screen doesn't grow HA anymore.

08-28-2009, 01:52 AM
I'm all for pulsed flow!
I have read Dynamic Aquaria several times. I bought it the week it came out. I actually came across it today as I was moving.

As mentioned it's more complicated to run pulsed flows. But more importantly it is often more noisy, which is a problem with most setups. It's one thing to have a trickling sound and quite different to have splish splash sounds possibly mixed with clicks or clanks for generating the pulses. I could see a biowheel as being a pulsed scenario with no pulse sounds.

Also while natural turf can be dry for hours and up to days even, and be quite happy, I am sure it isn't pulling any nutrients from the water it isn't touching. :mrgreen:

08-28-2009, 03:53 AM
Surge versus even flow.... Does it really matter? Yes sure, surge will give you the intertidal type of turf algae that seems to be the holy grail of scrubbing. I've personally never even seen the stuff. It's just a means to an end isn't it? Nitrate reduction, etc, etc. The algae growing on my screen is very similar to GHA. It has never changed, which indicates to me that it's the ideal type of algae in the environment that I've created. It does the job!

08-28-2009, 04:02 AM
Interesting.. Nothing like my turfs have been like.

08-28-2009, 04:51 AM
We do things different here in South Africa :lol:

08-28-2009, 12:15 PM

Now I see why you can see bubbles. My turfs wound not be enveloping like yours. Mine is more like um.. Astro turf. In your picture yours looks kinda like thick hair algae to me.

08-28-2009, 04:19 PM

Mine grew that very same algae. Mine also had started the turff on ist own. Once the turff got to were it is now, which is about half my screen. The algae you have, The algae I had, or HA doesn't grow on my scrubber any more. At least it hasn't in the past month. My algae is brownish red and doesn't seem to grow any longer then about a 1/4". When I clean mine I use the tips of my fingers and scrub it back and forth like if you were washing your hair. It breaks off in little pieces but never really leaves the screen.


Yes, the algae can't filter what it doesn't touch, that's for sure. However if a person isn't using the "optimum" lighting schedual (3hrs on-2hrs off)to keep the algae in its peak usage state then they aren't too far out of the same relm.