Every week I change my fish Fionas water. I do a 20% water change and always have. However, I check my water chemistry the day after the change, and have had some surprising results. Everything is perfect. pH is 7.6, Ammonia is 0, and Nitrite is 0. But one thing that always remains a problem is the level of Nitrate in my tank. Recently, it's been hovering around 10-20 ppm. This is bad I know, but I don't know what could be causing it.

So here's what I did. I added some tetra Nitraban I had but never thought I'd have to use. It said to add 5ml (1 tsp) of medication for every 5 gallons of water. This was unusual for me since I'm not accustomed to dumping chemicals in my tank. But without any other options at the moment, I added 6 tsp of Nitraban to my 30 gal tank. That seems like a lot to me, but that's what the directions said, and I didn't want to underdose only to add more chemicals later to an unaffected tank. Stressing the fish even more.

I'll check my Nitrate levels tomorrow, and probably do a 10 to 20 % water change. I need help with this, so please post. Thanks.

Have you tried changing 30 percent of the water each time, or changing 20 percent twice a week?