I felt my plants should be growing better so I added a very little
25-10-10 fertilizer to the tank (knowing the phosphate risk).  The pH
rose from 6.33 to 6.55 over the next 48 hours!  To me that means the
fertilizer aided the plants in taking up N (and thus raising the pH).
 So they must have been short P or K.  Any idea which?  I have been
using Flourish as well for micronutrients and I believe it contains
K.   So that might mean the tank was P limited?????   What do you all
think?    Dave

Dave Gomberg, Experimenta      San Francisco CA USA   gomberg at wcf_com