I've not heard of anyone having ammonia spikes from die-off from that product. My skeptical side says there's not much in the way of live helpful critters really in there anyway. To be safe, a good rinse of any new substrate is a good idea. There are sands that'll buffer that aren't the 'live sands' that may come cheaper. Maybe trade it in for one of those? I share your concern about dumping that bag water into the tank. More I think about it, I wouldn't do it. Your filters don't need whatever may be in there, so can only do more harm than good. I'd rinse it if you decide to keep it. :thumb:My concern is putting this stuff in my tank, and having the "live" critters die off, spiking the ammonia.