I really don't want this to come off as rude, but I get the impression from several of your posts that you don't actually understand the nitrogen cycle, or don't completely appreciate its implications on your choices/practices. Nitrates can be "pretty good." Nitrites are either 0 in a cycled tank or you have a problem-- there's no such thing as "pretty good." If you're going to be keeping stingrays it would be a really good thing to do some more reading on basic aquarium chemistry.no nitrate and nitrite are pretty good. and my ph is 6.4-6.6