More problems

Still have yet to find the source of the MG problem. I scrubbed the tank and did a water change today with MG enriched water but still no change. I didn't flush the water that i took out of the tank away. I've kept all 20L in a jerry can. Poured 10L into a pain and dosed MG supplements. I've yet to test the old water in the pail but if i'm able to raise the MG in there, then the problem is not in the water but in the tank. I'm beginning to suspect its the chemical filtration. That bag of nitrate filters is doing something bad to the water. That's my guess. stick around to find out more.