Hi everyone, Im new to aquarium world. I have about a 2 mth setup of a 20gallon tank. I have always wanted one and decided to go with it. LOL. It does have a filter (came with the whole tank setup). Ok so I started with a few danios and a couple weeks later got my water tested (nitrites a little high) but other than that all is well and the lady said I could add some more fish. so I added 3 more danios and a few guppies. Well my guppies died within 2 days. Tested water and nitrites really high. Bought api quick start, added one dose. Took water back following weekend and nitrites still really high. A diff lady told me to do 30% water change and recheck (bough a master test kit) and if still high do another water change etc etc. Well I did water changes for 4 days and nitrites still high in the purple. Called store back and talked to someone else and she said add api quickstart for 4-5 days in a row and dont do any water changes bc my bacteria needs to catch up. Took water back yeterday and nitrites still super high. Everything else is fine (all fish are still alive). She told me it could be the blue rocks, so I took them out and boiled them and added back once cooled. I tested water this AM and still dark purple in nitrites Im lost. I dont know what else to do. My aquarium is 2 mths old and Iv had high nitrites from the get go. Does anyone have any other advice? I was really hoping to enjoy this aquarium busness and hope to get a large tank, but Iv failed at this small one. I do have pretty aquirium decorations? maybe they need to come out.