I'm glad your algae is being beat by the GFO reactor. I'm loving mine as well. Based on what you're saying and the fact that you have tried different test kits, I'm inclined to suggest a salt change. I'm not sure what you're using, but it's definitely not proportional on the mineral mix. It is quite a puzzle, but if you checked your RO water, and it reads at 0.01ppm, this is obviously not the problem. Your salinity is almost right too. I would try to make it 1.025, but would not use your currently questionable batch of salt. What brand is it? I can't remember. One thing I want to mention is time frame. If and when you change stuff in the tank, you have to take it slow. If you reduce your alkalinity from 18dKH to 11 or 10 dKH in 1 day, your tank will not like that. Slow is better. - Mag.