I'm not sure if anyone here has read whether Amquel's makers did tests of water quality in labs to be able to claim that it can allow less frequent water changes? It may be that they DID do this research and that it DOES reduce the need for so many water changes. We need to be careful that just because WE think it necessary as part of OUR regime to change water every 3 or 4 days that we aren't denying valid research that would show that doing it every 5 or 6 days (for example) results in the same chemical parameters. If that is true, then the amount of product used is also reduced because you dose less often. Has anyone done that checking with Amquel+'s makers? I use Prime at home and Amquel at work, because my LFS at work doesn't stock Prime. However, I have nothing against Amquel+ but have just used Prime more often.