I did 75% water change and expected to see 75% reduction (40 down to 10). My tap has just around 3 PPM.
But it was just reduced to 20 PPM.... I had calibrated my test kit and knew
what color the 10 PPM should be.
After searching the net, many people were also having this problem.
Some said vacuuming the gravel helped. But the fact that NO3 is not affected
by CEC of the mulm....hmmmm. Anion exchange capacity? But eventually
after several WCs, it has gone down to where I want now. So I stop the
Root tabs, in my case, no it couldn't be, I'm sure. I'm anal enough.
But for the OP, I would suspect the stick.
Last edited by KH2PO4; 11-16-2012 at 11:22 PM.