how much, id be willing if its a good price, lol. well i would think it would need a source of ammonia to keep the benificial bateria. i would go less is more. i have a 5 gal
that i would like to put something in, but after it cycled, i put A LITTLE flake food in to keep it going, while i waited to put something in it, and it cycled again. now im waiting again. if youre thinking of selling alot and keeping it up, just throw a damsel in there to keep it going, if just wanting to get rid of some b/c you dont want it anymore, i would think a tiny bit of flake would keep it going until u sell it. jmo.