This is all very interesting to me as I am setting up the 4000 gal as everyone probably knows. Less engery consumption is a big issue. I'm already planning on using LEDs for the lighting, and would like to go cheaper on every other electrical component as well. Along with more efficient pumps, I wish I could find a more efficient way to heat the tank as well. Seeing as it is in an unheated garage and Montana has horrible winters....probably comparable to Canada(maybe). If only I had the money to do a solar or wind powered rig for this tank I wouldn't worry about it at all.
All of this kind of rings a bell as my tank and filters will all be the same level kind of like a pond. I plan on using 55 gal plastic barrels for the filter behind the tank. I had toyed with the idea of using the four corners as filters, but I think it will get very complicated when it comes to sealing the tank so for now I'm going with the barrels. Their cheap, and easy to use. I'm already using one as a filter for my 350 gal pond. Running two Fx5s as prefilters, and the barrel is sitting above them, and gravity takes water back into the tank. So is there any reason to think that I could use powerheads to push water back into my tank as it will be 0 head? I'm not sure on the logistics of this, but it's very interesting. I have one 5000 gph pump and had planned on buying at least one more, but if it can be done with a savings on electricity I'm all ears. Basically my plan is to have a large PVC overflow that runs into the first barrel and down to the bottom of the barrel. The pipe goes all the way flush with the bottom. There will be slits cut into the side of the pipe up to about 10" above the bottom. There will be egg crating or something that is held at that height. On top of that would be placed filter floss, and more crating on top of that, which can be removed for cleaning/replacing filter floss. The part below that would act as a settling chamber which I want to activate with an air pump or somthing similar, and it will have a side drain that will run through the wall outside for backwashing the settling chamber. After the water works its way up through the floss it will overflow through a large pipe into the next chamber which will have scrubbies/rocks/ect for added bio filtration. After it flows through several like this it will enter the final chamber with just pumps and heaters before being pushed back into the tank by pumps. Was going to use one pump to push water through a reverse undergravel filter, and the other will just push back into the tank itself creating some current. Does this sound feasible at all?