In Dec. I bought a new 12 gal tank to replace my 8 yr old 12 gal tank. I was fighting GHA and took out all the rock except what had coral growing on it, which wasn't much. When I got my new tank and switched them, I was afraid of it re-cycling. I added 10 LBs of LR to the 12 gal, and 5 lbs of LS. Levels all 0 (amonia, nitrate and nitrite). 3 months later still 0.