I am often come across things that say x species is intolerant of organic wastes or you should avoid a build up or organic wastes but this got me thinking as to what they actually were I guess I have only really though about waste in terms of the nitrogen cycle and when a fish poops or leaf decays that breaks down to ammonia => nitrite => nitrate... Are organic wastes just anything containing carbon and if so does that really just mean poop and dead flora / fauna? Evolution Aqua Pure says it contains Heterotrophic bacteria which consumes organic wastes but presumably as leaves decompose in your tank normally I guess these or similar must be present in the tank anyway? So given flora, fauna and poop all decompose in the tank, what is it that builds up or is actually bad? I guess decomposition will consume oxygen so reduce the amount available for fish, plants and nitrification bacteria but this could be counteracted by more surface agitation to keep oxygen levels up? What am I missing?