Raise your Nitrates, I would test your Phosphates before your weekly water change to see how much it has dropped since the last water change. Ya want your Phosphates to be at 2ppm minimum to stave of the GSA. Depending on your plants, Crypts and Anubias love the potash.
I have no phosphates in my tap, I do a once a week heavy feeding and it raises my phosphates between 5-7 ppm and after 5 days it's at 2 ppm, With my stocking I'm at 30-40 ppm Nitrates. I'm dosing Flourish Potasium at 16ppm a day, I was dosing Easy green, but gonna jump to NilocG S because I don't need the extra Nitrogen and Phosphates.