test kit is by Red Sea called "fresh Lab" includes tests for
Nitrite,Ammonia, and PH (one for 7.4 and one of 7.4)

I'd check the Kh, as it plays a very important part in keeping your pH
stable. If you don't have a Kh tester. Do a pH test in the AM and PM. If
there is a wild swing of more than 0.4, one could have a problem with low
Kh. ~ jan
~ jan