I use this brand called black diamond and got it from tractor supply store and it comes in different size, I get the 20 which is pretty fine but not fine enough to get sucked up easily into filters. I keep large south american cichlids along with a couple of africans and they seem to love as I have been using this for over 2 years at 8.00 for 50 lbs you cant beat it, but you have to wash it thourghly in a 5 gallon bucket with a powerful nozzle on your hose until water runs clear.
