i put 3 tetras in a 10 gallon with my beta. Everything was fine for the first week, but then one morning I woke up to see everyone in the tank had icy. I imidetly did a 50% water change and started dosing ich-x. After 2 days everyone seemed better but the day after that my tetra was stuck to the filter on its side still breathing but almost dead and the other tetra and Betta were also very slowmooving and coverd with ich. My water tests came back normal what should I do