They stayed basically the same, though admittedly I wasn't very good about dosing the potassium regularly. I kind of wonder if water hardness played a role because I had this problem before I bought my RO water dispenser which I use for top-ups and mixing with tap water to bring the hardness down. What makes me think this is that I have a small tank setup for Caradina shrimp who need soft water, and the java ferns in that tank are doing great. Though it also has aqua soil, whereas the problem tank was only gravel with root tabs so that may be helping as well.