It started about 2 years ago with this thread: http://algaescrubber.net/forums/showthread.php?1181-The-Great-Algae-Light-Source-Experiment But it's more than just testing the light source. Now, it's about testing the effectiveness of many different aspects of scrubbing: Nutrient uptake rates Growth types Growth rates Simulation of limitation Light sources Light spectra Flow rates across screen (waterfall) Upflow scrubbers Horizontal scrubbers (why not) Screen aeration pH manipulation Whatever else I can think of Anyways, the crux of the issue for me has always been the source of nutrients. Trying to create a concoction that simulates the conditions that an Algae Scrubber is normally under seems very complex and seemed to be missing certain aspects that, to me, always seemed to throw a wrench in the process. Last night, in a fraction of a second between movements of a toothbrush, going one direction and then shifting to another, I realized how this could be done. Start with a large tank, heavily fed, with lots of rock, fish, softies, LPS, etc, and cure up a bank of Algae Scrubber screens. After that, this large tank becomes the source of test water. We will call it the Source Tank (ST). Now take the scrubbers off and place them over small testing tanks. These could even be buckets for all that matters. These will be called the Test Tanks(TTs). Drain water from the ST and fill the TTs, replace the ST water with freshly mixed SW (like a PWC). Run the scrubbers on the TTs for a designated length of time and monitor the results. Right now I'm focusing on the basic setup that will apply to all test cases. Here are a couple of possible setups. Have a single event water transfer from ST to TT at the start, and just let the scrubbers run on that for a period of time. Use a doser to pull (strained/filtered) water from the ST to TT periodically. Must be a good doser. TTs would have some water drained out prior to refilling. Set up relay and float system that will drain a certain amount of water out and then fill it back up periodically. Just a few thoughts on the methodology. I think #2 or #3 would be better than #1, because as nutrients drop, growth could change. It might take some time to find a 'sweet spot' in which infusing the TTs with ST water does not cause a radical shift in growth type. This also may be a reason why #1 would not work well. Running the scrubber in a 5g bucket until the water was "clean" and then dripping in 'dirty' water would in essence dilute it to the point where it would be at a perfect concentration for growth. I have been hanging on to several L2 boxes that have minor errors in the acrylic in hopes that I would eventually figure this out. I have about 6 such units set aside. I have a basement storage/furnace room which I have recently converted into a fish room. I now need to keep it that way bwhahaha. I have over 600 lb of rock, 400 of which is dry base rock, about 200 that was just pulled from a dirty tank, and another 100lb coming in that is cured. I have a 120g tank that I have been running the UAS on, and it keeps nutrients N>20 and P>0.20 generally, so that might be my ST. However, most of the stock in this tank it not mine, and I hope to be giving it back soon. That tank also has a weak seam due to initial set of the tank, and I'm acquiring a 75g soon which will take it's place as my personal tank. So this 120 can be moved to the basement and set up as my ST. This room also has RODI and a 100g storage tank. So it seems that at least on paper, this experiment might be coming to reality relatively soon.