I tried searching for this but just getting more confused. We have a 55g QT/observation tank set up and put 6 fish in a week ago. It has a HOB filter and sponge filter with 4 pieces of rock that were dry. Treated it a few days before the fish with Bio-Spira. Using Safert kits and a Hanna Checker for Phosphate. Ammonia is undetectable to my eye and I have a Seachem badge that says it's safe. Nitrate is 10, Nitrite 0 and Phosphate .32 4 days ago Nitrate was 5 and Phosphate .13 Is there anything here I should be concerned about and do I need a water change ?