I fully concur with AdoraBelle's advice of a major water change as soon as possible. Use only a conditioner, no other substances, and do a good vacuum into the gravel while sucking out the water. [You posted while I was typing, yes, do the 70%.]
Going forward, you mentioned doing tests and levels are perfect...always post the test and the result, as we don't know what someone may consider "perfect." Parameters are GH, KH, pH and temperature. Conditions (not technically parameters) are ammonia, nitrite, nitrate, [and some other test that generally don't get involved].
Going forward, you mentioned doing tests and levels are perfect...always post the test and the result, as we don't know what someone may consider "perfect." Parameters are GH, KH, pH and temperature. Conditions (not technically parameters) are ammonia, nitrite, nitrate, [and some other test that generally don't get involved].