UG filters are considered old-fashioned nowadays. If you want plants, UG filters are not recommended as they cause too much disturbance on the plant roots which can upset the plants.DanaJ said:My fiance's coworker(who has a 35 gallon tank, I think) mentioned an under gravel filter (?) Are they good generally or should they be used for specific tanks etc? Pros and Cons?
If your substrate is sand, UGFs will clog easily. There is a tendency for UGFs to create anaerobic(or dead) spots which can harm your fish as dead spots simply release toxic substances.
Cleaning is often done by an almost strip-down of the tank.
I have no idea how reverse-flow undergravel filter actually works but here is the link about it unless some members here provide lots of information about it. I've never gone to this matter yet.