High nitrate

What would you do with a high nitrate level, when all other tests (PH, Alk, Hardness, Calcium, Nitrite, Ammonia, salinity) are good?

[jamal-188]

It's from an build up of nutrients. Most have a DSB to help reduce nitrates. Bio balls will also increase nitrates through the build up of nutriends. Do you have a DSB, bio balls, a skimmer?

Yes, I have them. Maybe it's been recent overfeeding, and I also had removed the skimmer for a couple of weeks because an O ring failed...I just set it back up again.

Thanks.