I hope someone can help…..I set up a 20 gallon tank a couple of months ago. Tank has cycled and water parameters have been normal (Ammonia 0, nitrites 0, nitrates 5.0, pH 6, water temp 79) but I am having fish die as well as my plants don’t look good. I listened to a thousand you tube videos, asked numerous different employees of fish stores and get different advice and answers from everyone. I did a 30% water change 4 days ago and lost 2 fish within an hour…a Dalmatian Molly and a guppy. I currently have 3 mollies and 6 guppies and one guppy is staying at the top of the tank very lethargic. Water temp was high, around 83, but I have cooled that down to 79. I just don’t know what I’m doing wrong. Can someone please help?