hi fish friends, i have had my tank for 5+ years, 3 months ago i changed stones for sand (looks great)problem now is unsightly waste on top i've tried the lot, siphon, sieving it through my net, i have just put sludge buster in, becuause i keep up-rooting my plants, how long will S/B take with 2wk dosage's..... sorry for sounding like an idiot......thanks