i have used it. i posted a thead about it awhile ago asking about it and i got the same responces. although it is true, nothing beats a water change, this stuff actually did wonders. my friend used it first because he was battleing nitrate issues. the dose it weird. day 1,2,3,4,5,90. by day 5 he had 0 nitrates! he was at around 100. now 0. i used it as well and noticed the same results. it acted like a just did a 100% water change. my water has always been clear, but this made the water as if there was no water in the tank because it was so crystal clear. i loved it. completely killed any smells, poor water pars, water cloudiness and ect... does what it says. although they claim no water changes for a year...i dont know about that. im still doing them, just not as frequently. good luck with it. i liked it.