I got 2 platies from Petco (gift card). One died overnight so I took it back with a water sample for them to test. I also tested my water as I just cycled a few days ago and the levels were ammonia 0, nitrites 0 and nitrates 10-20. I use the app freshwater test kit. They used strips there a d said everything looks good except my alkalinity is low. They said that shouldn't effect the fish and will jist cause my ph to change so I may need a pH stabilizer. However I test my pH often (not today) and it is always 7.8 so I told them my pH doesn't jump around. Any thoughts on all this and if I should do something about this ? It is not something I test for as it isn't in the kit.