Like everyone else said you need to thin out your stocking.
Get a better Nitrate tester. I am sure your Nitrates are much more than 0. Infact if everything is working the way it should, a fresh water tank will have nitrate in it. That is just telling you that your nitrogen cycle is working.
Get a better Nitrate tester. I am sure your Nitrates are much more than 0. Infact if everything is working the way it should, a fresh water tank will have nitrate in it. That is just telling you that your nitrogen cycle is working.