Yes, I have used test strips and kits. I had ran out at the moment and had ordered a new test kit. But I do not have at the moment now I am waiting. I had my water test at a pet store and they said the water was not the issue and to give it a couple days. Now I have four platys that are acting completely fine along 2 otos and 2 corydoras in a 20 gallon tank. 2 platys out of 8 have died, and now 2 are acting weird and hanging out at the top of the surface. But the others are fine. What should I do now! If it’s a KH or GH problem how can I fix that? Thank you