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Sizing a scrubber based on feeding (guideline review)

Discussion in 'Basic Principles' started by Allen Repashy, Dec 12, 2012.

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  1. Thought I would toss in some observations.

    Recently while looking at the "other algae scrubber" site I saw that SM had stated that additional size was needed if you had an older system, a system with a lot of accumulated old algae and other organics and so on. He stated that if you were putting an algae scrubber on an older system with these issues you basically needed to double the size you normally would use based on the feeding guidelines.

    Now this was the first time I saw anything like this from him. Usually he goes on about phosphate in the rocks and stuff like that.
    However, my experience seems to agree with what he was saying here in a general sense.

    An older system with established live rock, with lots of stuff accumulated does have a lot of organics in it. A system with a sand or gravel bed does as well.

    When you add in an ATS you are trying to use up the nitrates and organics from what is not only being put in every day but what has accumulated over time.

    Then when algae dies off, you even get more organics which the system has to handle.

    I wonder if in situations like this we need to think of using a skimmer, carbon and other things to assist the ATS, at least for a while???

  2. Turbo

    Turbo Does not really look like Johnny Carson Staff Member Site Owner Multiple Units! Customer

    I saw it as partially making sense, and partially backpedaling on his recommendations.

    To me, it was obvious that he had done zero research on capacity of UAS devices. But they needed to be small, and needed to still be able to handle a bioload. In comes the handy guideline change a few months before he releases his UAS, and the UAS happens to fit nicely into those guidelines.

    The problem was that the UAS, IMO does not perform to that guideline. There are certainly ways to make a scrubber more efficient. I think the HOG scrubbers seem to be one of the most efficient for as simple as they are. But they are flow limited, thus you can't really "push" them to perform better, or at best, there is a limit

    Waterfall scrubber have a similar "upper limit". If you DIY an open-air one, you can work with things like flow, lighitng (both source and intensity), etc to make it perform as best as possible, but if you build a really junky one, or are short on one of the main factors, it's likely to underperform a bit. So that's where his recommendations for oversizing seem to make the most sense, but he doesn't make that clear - he's applying this blanket statement to all scrubbers, of all types, and that I do not agree with.

    Call me biased because I make them but when you consider that an enclosed-box LED scrubber is really on the upper end of the guidelines, then add in the light/spray blockers which allow for the flow to be better maintained throughout the growth period, then add in that you can crank up the flow without getting water everywhere, well you see where I'm going with this. A scrubber that is built to well-exceed the "basic" guidelines of a simple DIY build is very likely not going to need to be doubled in size when the tank conditions are bad.

    I've seen him mention that for every 50lb of "bad" LR you have, add 1 cube/day of feed for "leeching". I asked him where he came up with this figure and he just posted his guideline. What I was asking him was how he came up with the figure to justify the guideline. I'm guessing it's just a ballpark guess based on some anecdotal evidence. But again, he states this as a fact. It will do some people good I'm sure, but if you look closely at the guidelines he mentions "getting more scrubbers" and then "selling them" i.e. get extra HOG or SURF units. There is always a marketing aspect to his recommendations. I can't say I'm not guilty of that either, but if I even tried to do any marketing at this point I would be backlogged more than I am, so I pretty much just say what I think and let the chips fall where they may. I disseminate information based on what I know works for me and my customers, not necessarily with the intent of driving people to buy from me, but rather just to help people with their DIY builds. I don't really "need" to sell scrubbers, since I haven't dumped tens of thousands or $$ into patents. But I really "need" to build them for the people who have asked to be put on my waitlist!! I've had two or 3 60+ hour weeks in a row...ugh...at least it's my own company.
  3. I take most of what SM says these days as marketing.

    What I am seeing with my own system and my own home made built waterfall scrubber is that it does a great job keeping nitrates down and phosphates down, and seems to keep algae growth somewhat under control, but not totally.

    At the present time I am running as much flow over the scrubber as my overflow system can handle for my tank. The screen size is about 5" wide by 8" long, over a screen that has been cured over at least 2 years at this point. Two sided. so about 60 plus useful sq. inches of screen.

    I get a lot of green growth and a mix of green slimey growth - but not that much turf algae at this time

    I feed about 1 cubes worth of stuff daily on the average. With this amount of food, this amount of surface area and the flow I have, I still get some turf algae and briopsis algae in the display tank and now a lot of cyano. The algae seems to be slowly dying off, but still shows up in some places, on the glass and so on.

    I have a lot of waterflow from 4 different water pumps as well. [29 GAL high tank with another 10 gal in the sump.]

    The system has been running for 8 years at this time, with an ATS in some form or another for the last 3.

    And only a waterfall for the last 1 1/2 years. Sometimes I run carbon and GFO - but not always.

    There are times when everything is great, the corals are growing like crazy, and although I still get some algae, everything looks healthy.

    Then the weather changes, things change, and some of the Xenia corals start dying off for no reason I can see in some areas. I start getting more red cyano and things don't seem healthy.

    Then I pull out my hair, start adding iodine, run carbon again, and so on.

    Nothing seems to keep running nicely over a period of time for more than 4 months or so before stuff changes.


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