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.
Sorry to disappoint you, they are still in use and for many breeders it is the preferred method of filtering right there alongside sponge filters. As I said in my earlier post, proper use and setup makes a huge difference as it does with any filtration system. Most people don't set them up properly to maximize their full potential. As far as their age of inception, I was using them in the '70's and even then they weren't new. They are still being offered today so don't say they went out of date in the 80's. If they didn't sell, they wouldn't be available.Good, sand is better anyways. UGFs were around before the 80s, but went out of date about that time.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).