Agathokles, this is one of the most amazing threads I have ever read.
Thanks for posting your video. Compared to my bulky 17 year old fish yours look like mere youngsters that you bought a couple of years ago, though I absolutely believe what you say of course!
I am amazed to hear from you that UGF plus vacuuming actually lowers nitrates as well as clearing up the ammonia, nitrite and organic particles. This would explain why I can have several large fish and yet the nitrate level stays the same as in the incoming tap water at 5pppm. This will help the health of the fish no end.
NancyD, it seemed to me that reverse flow UGF was a passing fad that didn't work and was ridiculous in concept. You didn't miss out on anything. Instead of trapping the particles in the gravel it blew them into the water column making for a very unsatisfactory view. I was advised to use it when I started and quickly changed my mind!
6 x Clown Loaches all 30 years of age on 01.01.2024, largest 11.5", 2 large females, 4 smaller males, aquarium 6' x 18" x 18" 400 ltr/90 uk gal/110 US gal. approx.