i have a tank set up with approximately 40 pounds of aragonite crushed coral and roughly 40 pounds of rock and was wondering what kinds of plants i should use to lower my nitrate levels. Maybe my test kit is defective but i do weekly water changes of at least 10 percent. Ammo nitrites are always 0 ph around 8.2 and a KH of 6. Water temp is 80-82 nitrate reading of about 20-30 ppm i test the water out of the tap and it tests 0 nitrates but after just a few minutes after a water change its back around 20-30 ppm it never gets any higher than that but am concerned about the long term affects of it on my fish