Single-sided screen with forced flow

There is a user on RC (Scolley) who built a single-sided LED scrubber and he inserted the screen into the tube and siliconed one side to force the flow to only one side of the screen, and then feeds it with 1/2 the normal flow (I think 16-18 GPH/in). He does not have a high nutrient system but is getting bald spots and I've been trying to pin down the reason.

My rationale was that since the flow is forced to one side, the algae growth forces the water to flow over the top, leaving the lower layers starved of water, and this would cause them to detach. He has big clumps of growth near the detachment area. Look at this pic on his post #1605...

http://www.reefcentral.com/forums/showt ... ?t=1977420

...and then look at the exchanges back and forth between me, scolley, srusso, and TheFishMan65. What do you think?

Also, the last post (1651) by fishman brought up an interesting point, SM perhaps you could comment:

Quote:

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One other possibility that I admit I don't completely understand, but from reading think it could be a problem. What do you think?

If there is no/low flow in the anchoring level, then it may go anaerobic (no oxygen). Would/could it then start to produce Hydrogen Sulfide? Would this eat away at the anchors?

I understand the principles behind this, but not all the requirements. So I am throwing this out there for discussion.

Thanks

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Any rationale behind that?

here is a direct link to the post...
http://www.reefcentral.com/forums/showp ... count=1605

I disagreed with Flyod on this thread. I believed that it was copepods eating the algae.

One additional piece of information that he didnt make clear was that he hadn't yet cleaned the screen which I found out last night at our reef club meeting....

But after looking a few times, Floyd does have a point about it being algae detaching...

scolley's in your club, eh? I think I remember you telling me that now. How long had he gone without cleaning?

In general a one-sided screen will let go before two-sided, because of light.