I usually drill holes close to where the water surface will be, on a side, or back of the tank, and either use upturned PVC elbows, or just screw a strainer into the bulkhead.
The most toxic stuff (although most it's almost invisible, such as oils , proteins, semi dissolve organics) collect at the waters surface, and hinder gas exchange, so surface skimming helps remove it.
The poop to me is a minor detail, which should be removed with siphoning during water changes.
The most toxic stuff (although most it's almost invisible, such as oils , proteins, semi dissolve organics) collect at the waters surface, and hinder gas exchange, so surface skimming helps remove it.
The poop to me is a minor detail, which should be removed with siphoning during water changes.