A nitrate level this high, long term isn't good. It wouldn't hurt to do a little larger than normal water change as soon as possible and wait a couple of days and retest. Small tanks under 30 gallons should get a 50 percent water change a couple of times a week. Larger tanks should get half the water removed and replaced every week. Do this, and you'll have few, if any tank problems.
Last edited by MultiTankGuy; 03-07-2018 at 07:31 PM.