I tried a lot of different water schedule, everyting from every 3 h for 10-30 min, and every 2 h for 12-15min, but no result. That way I desided to try every h for 5-7 min. I have a pump in the res for better circulation of oxygen. And the medium, I dont know how u call it on english, but stons are light with a lot of houles. I`ll take a picture. Thanks for helping