The RUGF on the 90 at one shop I worked at did not work. When we finally tore it out the visibility in the tank literally went down to 1-2". Nice theory, but just stick to real filters.
I agree Bob just because its old school doesnt mean its not effective you just need to know how to maintain them. I have had them in operation for 5+ years with out being torn down and never had any problems and minimal waste under them.LOL...will disagree with that on many counts....but thats what makes the hobby fun.
Good, sand is better anyways. UGFs were around before the 80s, but went out of date about that time.
I don't see the need to be diplomatic about hurting UGF's feelings. They are old school, ineffective, extra work, and cause more harm than good long term. They provide NOTHING that a more proper filter can't (except the extra work and problems).