G'day I'm interested in hearing about anyones experiences regarding using an algae scrubber as a main filter on a marine aquarium keeping meat eating fish, ie - prawn, mussle, squid. Does a scrubber, in these circumstances, process the waste as efficiently as an aquarium feed just nori of flake food? Are very low NO3 levels able to be maintained by a scrubber processing fish waste on a meat diet? Does the type of algae that grows change from green hair algae to something else? Does the screen size need to be larger? Would be good to get some feedback.
Good question! The theory has basically been that you can break everything down into a "equivalent" to a frozen cube. One method of doing this would be to take whatever food you are using, and blend it up into relatively small particles (not super fine, but not huge chunks) and then use something like a rotifer sieve to drain out the water, and take whatever you have left and "pour" it into one of those cube trays (like the ones from Ocean Nutrition, Brine Shrimp Direct, or similar) and that is how you get the "cube equivalent". Planning your Algae Scrubber Now you can imagine, if you have a full can of flake food and you pour that into some water and blend and strain that, you're going to end up compacting that down quite a lot - which makes sense. The "cube equivalent" in flake food has been purported to be 10 pinches but that's an old Santa Monica factoid so who knows if that's really actually true - but it's probably in the ballpark... So with chunks of meat, this eventually gets digested and excreted just like any other type of food, so the input (to the mouth) is not necessarily relevant, because in the end, it's all output the same (urine/feces). Now that being said, in general, your big meat-eater fish are going to be fed more, so your screen size would go up accordingly.
Its the excreted waste that matters. Feces from a prawn diet would be far higher in protein. What chemical reactions would take place in the decomosition & what toxins would be created? If, for arguements sake, only one form of filtration was to be used in the case of a meat diet, perhaps a biological - bacterial filter would be more benificial? I don't know. I do know that if I leave a prawn out in the sun for a few days it will smell far worse than if I leave a piece of Nori out in the sun for the same duration.
Probably a better question for a biologist, I couldn't knowledgably answer that, but I'm interested in knowing! Bacteria grows on a scrubber as well
Thinking a bit more about this I don't think it would make any difference what you feed the fish in relation to an algae scrubber. Whatever you feed them it is particulate organic carbon compounds. What goes in the fishes mouth comes out in two ways. Ammonium through the gills from metabolisation of the food (taken out by the scrubber). The rest, the poop - detritus, is still (partially digested) organic carbon compounds, bacteria food, coral food. And any of the poop mineralised becomes ammonium anyhow, thus, the scrubber will take care of that.
