Zinboy, RUGF means reverse Undergravel filter.
UG filters were invented in the fiftees for fresh water. We used them for years and they made a real mess and had to be cleaned often. When salt tanks came out in about 1972 all we had was the old UG filters we used in fresh water so we used them. There was no alternative. There was not even sand sold for salt tanks. We were limited to crushed coral or dolomite.
I have dolomite. It has been in my tank since the tank was brackish in the sixtees. I first used the UG filter like it was used in fresh water and had the same problems that we always had. It need to be cleaned often. Then I started using it in reverse by pumping water down the tubes in stead of using bubbles to bring water up. This was an improvement but it still got dirty and needed to be cleaned. I experimented for a few years and for the last 30 years or so I have been running it in reverse but very slow and with a sponge filter on the intake. I ran it for 25 years until I removed it to see what it looked like under neith it. It was not as bad as I thought it would be. It was full of tiny tubeworms and fan worms. There was no dead spots and no hydrogen sulfide. Of course it was dirty. I still run my tank this way and have bred many fish and kept corals for years. Almost all of my corals were LPS. I like them better than SPS.
I am just about the only one you will find using this system as I think I invented it. It has worked very well for me for all these years but it is of course not the only successful way to run a tank. I believe it is the best, least maintenance, longest lived system you can have, but of course that is only my opinion.
Here is an article I wrote years ago about the tank and the history of the tank in general. It appeared in either Aquarium Fish Magazine, FAMMA or Aquarium Fish Monthly, I don't remember which one.
Have a great day.
Paul
Reef Central Online Community
I don't know if I can post a link here like this. If not, moderator, please remove it