They are extremely potent. After quite a bit of trial and error, I found using the smallest size phosban reactor, plastic screens instead of black sponges, and probably a cup or so of npx bioplastics. Water flow fast enough to just churn them a tiny bit (not to much or you'll fill your tank with bacteria) and a couple days. You will almost for sure get a bacterial bloom, but it will go away in a couple days. Just don't use to much.......like I originally did. Oh and I have a 90 gallon tank. When I used the recommended amount, I couldn't get rid of the bacterial bloom. My local fish store sells everything, and they swear by them as well.