Hello all,  I am very new to this and am planning on making a 3ft vertical system made with PVC, with a 31 gal. tank.  From what i have researched expanded clay pellets would be the best grow media, I am trying to find a suitable water pump.  I am hoping for any and all suggestions.  I am limited on space and have a weight limit because I am on the 3rd floor of an apartment building  and am plann…