I have a question along the same lines. Last night, right after I added 4 new gouramis, I checked my levels and had PH at 8.2, Ammonia 0, Nitrites 5, and Nitrates 10. I have a 55 gal with some plants, 8 danios, 1 striped Rafael catfish, 2 eartheaters, and I had just put in 1 pearl gourami, 2 giant gouramis, and 1 green severum. My PH usually stays at 7.6 and my nitrites at 0. My nitrates last week were 5 so they came up just a little. No one has died as of yet. I did do a 40% water change after I got my results and added Prime. Should I wait and see what happens tonight or do another water change anyway?