Nitrites in saltwater will be experienced in most cases. If they fail to drop after 1-2 weeks, you may be experiencing a phosphate block. You can eliminate the phosphate block by adding Fritz pH Lower at the rate of one drop per 4 gallons of water (do not exceed this amount or the pH in your system will be affected). The nitrites should begin dropping in approximately 48 hours after this addition (one time only). A second dosage of FritzZyme® may be necessary.