I HAVE HAD MY TANK ABOUT SEVEN WEEKS. I HAVE TESTED THE WATER AND EVRYTHING IS FINE EXCEPT MY PH. I HAD TO DO A FEW PARTIAL WATER CHANGES TO BRING DOWM THE AMONIA. NOW I HAVE PH SO LOW THAT MY FISH ARE SWIMMING AT THE TOP OF THE TANK, EVEN MY ALGAE EATERS. I HAVE TRIED TO BRING IT UP WITH A...