What are your thoughts on underground filters? And if your for undergound filters, do you think its neccessary to have both a power filter and a underground filter?
I myself like canisters and or sumps. My LFS swears by under gravel filters. He states that the amount of beneficial bacteria in the substrate are unbeatable compared to canisters or HOB.
They are probably the least effective filter there is especially when relying on air to run them. Running power heads in reverse they are not too bad but still the least effective and prone to be nitrate factories.
For me personally I think they are a major help for filtration in which all my thanks have then except my 150gal because I cant find none for it and I cant have sand with it.