Thanks Prof M and Tom for your replies. I will try reducing the PO4 next time. So, should I just keep the NO3 amounts the same from what I had been using, but with the KNO3 instead? The problem is is that I have very large tanks that I am dealing wtih (about 3600 gal), so using products like Kent are not practical. I am not familiar with DTPH or Tropica, but will look into them. We normally use regular agricultural fertilizers since we generally use 200-300g per dosing, per tank.

Thanks for your advice,

Christine