Did a 50% water change on Sunday and turned my CO2 back on today, had it on really low. CO2 had been off for a few days to let my shrimp acclimitise. Tested my PH and it's dropped down to 5.7, KH is 0, GH is 6. Not sure what's gone on, I did my normal water change, RO water with Salty Shrimp GH/KH+, I did top it off with a little straight RO, but I would say that it was less the 5% of the water change. I've turned off my CO2 to see if my PH rises, but why has my PH dropped so low and where has my KH gone? Is this something to do with my Tropica Aquarium Soil? Tanks 55l, only things in it are plants and cherry/amano shrimp.