Hey again,
Test strips are reputable for inaccuracy. When the LFS tested my water with test strips, they said I had a pH of 6.4, .5 ammonia, and 0 nitrites and nitrates last time I went. When I checked with the liquid test kit, pH was 7.6, 0 ammonia and nitrites, and 20-40 ppm nitrates, and I tested it twice. You could be guessing basically with strips. JME.
Do the Stress Coat and Stress Zyme nuetralize ammonia, cholrine and chloramines and other harmful stuff from tap? I'm not familar with the product.
Also, those pH tablets could be killing your fish. Those things not only cause rapid and massive pH swings, which can shock and kill your fish, but release harmful chemicals that can kill fish as well. Your fish might be shocked and poisoned from them. IMO leave your pH as is. Especially with those fish. They're hardy and thrive in that pH.
Also, how did you cycle?