Originally Posted by lukac123
So Iím nearing the end of the cycle. I did a 90% water change last night and my nitrates are still high. How do I get them down. My ammonia and nitrites are 0. No fish in the tank. When I did the water change I didnít vacuum the substrate. Should I do another water change and vacuum the substrate?
Nitrate is the end of the Nitrogen Cycle, so for this form of nitrogen to be lethal to fish, it has to be in the 50 parts per million range and remain there for several days. Ideally, you want to keep the level around 25 ppm
Most tap water has some level of nitrate. To lower it, use a nitrate reducing filter medium like the products from Acurel and HBH. Add some floating plants like Anacharis, Hornwort and Water sprite. I immerse the roots of the Chinese evergreen in all my tanks. This works better than anything I've used. The plant roots will significantly reduce nitrates in the tank water.
Keep the water changed. I change half or more every week to keep the chemistry steady.