Also, i belive i read somewhere, and i can def say that it is true becuase i use organic nutes, apparently the extra oxygen being pumped into the water, does something to the dissolved nutes, i end up with alot of crap at the bottom of my res that doesnt mix. Only with organics. But to my unserstanding if you dont have a problem with the nutes in the res then a airation method in the res is a very good idea. Also you need to understand that the air pump is directly putting the oxygen at the bottom of the res, allowing the oxygen to attach to particles in a matter as it rises to the top. in normal condition where there would be no air comming from the bottom, the only place it can come from is the surface.