Algae scrubbers - do they work at all?

[smidoid]

Browsing the web I came across this research paper abstract (I can't read the whole paper since I don't subscribe to the mag) but the conclusions are anything from a little odd to worrying. Does anyone have anything to offer on this? I know it's a HUGE aquaria in this experiment, but I wonder in particular (a) where the copper came from (b) why such a negligble effect was noticed in nutrient levels or O2 sat. It seems to contradict the whole idea of algae scrubbing.

Abstract
The 4.5 m2 algae scrubbers were shown to have no significant impact on the amount of attached or suspended algae in the 30,000 liter display or on the concentrations of ammonia, nitrite, nitrate, phosphate, or dissolved oxygen in the water. Algae scrubbers significantly raised the water's copper concentration. The month-long experiment was conducted in the Coral Reef Tank at the Omaha Zoo.

Warren W. Pryor 1, Daniel J. Morris 2, Lee G. Simmons 2
1 Fort Wayne Zoo, Fort Wayne, Indiana
2 Henry Doorly Zoo, Omaha, Nebraska

[Steven Pro]

Would you mind providing the link to the abstract?

[smidoid]

Not a problem, here's the whole thing (at least, what I can get at.)

http://www3.interscience.wiley.com/c...TRY=1&SRETRY=0
http://tinyurl.com/jhz2a

This one really intrigues me. These guys seem to know what they're doing: yet where the heck is the copper coming from?

I also found an interesting piece on mangrove plants here:

http://toptropicals.com/html/aqua/pl...ngrove_eng.htm
http://tinyurl.com/gz2bj

Not only are these plants ideally suited to tropical aquaria (warm and humid) but the author's research seems to suggest that with a sufficient number of mangroves, LR and LR in your sump (and/or main tank) you can, in time, dispose of the protein skimmer and perhaps even 20% water changes! That's a bold suggestion, but it's just begging for further (preferably peer-reviewed) research.

[Steven Pro]

I know an aquarist at the Henry Doorly Zoo, and I am supposed to go out there this August and give a presentation, so I will ask him about it and see if he can send me the full paper to read.

[smidoid]

Wowsa! That's fantastic. I await the results with eager anticipation.

I have a DIY interest in it as I'm working on an gas-exchange-algae scrubber as an addition to my fuge. (I've posted the full theoretical design in the DIY section with the whole thing designed as a fuge from the ground up. This one is for discussion and exchange of ideas as it doesn't actually exist yet in that form.)

I just find it hard to swallow that the scrubber doesn't work: at all. Perhaps the experiment didn't have a properly monitored control?

The problem of coming back into this hobby after such a long break is my mind has gone into idea overload and I'm churing out new designs for all sorts of things faster than I can (properly) draw them.

[Steven Pro]

I got a copy of the full paper if you would like to read it. One of the problems I noticed was the experiment didn't go for very long and the authors admit as much in their own writings. "One interpretation of these results is that the experimental treatment periods were too brief. Seven days may not have been long enough to demonstrate long-term effects of algae crubbers. This possible source of error could be the subject of additional research."

[smidoid]

Thanks for that offer, I'll glady to accept. Seems like an odd experiment - a year long trial would have been better. I think (thought) it was accepted that all biofilters took some time to establish - bacteria is the classic one, but I don't see why algae should be any different.

Question for you: does it say if these scrubbers lit - and if so, by what. The reason I ask is that I've heard (and it's unconfirmed) that some algae thrive in one wavelength, where others (and most plants) do better at different ones. I might have gotten that wrong, so I'm at the mercy of those more knowledgeable than I.

Just for other readers - do you get any inkling of where the Cu came from?

[Steven Pro]

It was lit with a 1000 watt MH lamp. But, the screens were submerged the entire time. From the numerous ATS systems I have seen, the most important factor for good production is that the algae screen gets exposed to air. The best designs are like a teeter-totter with two screens, one on each side, and while one is submerged the other is exposed and then they are vice versa.

[Steven Pro]

As to the copper, that makes no sense.

[smidoid]

So it was a bad experiment, I guess. Pity it got published - I thought peer reviewing would have weeded that out. Guess not.

From what you say here an algae "waterwheel" sounds like the best bet for us small system guys. Guess I'll have to re-think my folded design. Bum.

(Ah! Have an idea - going to sleep on it.)

Thank you for that clarification (you'll find the butt-kissing elsewhere!)

No seriously, I appreciate your time and expertise.