Thanks Watermom.

FNC1962,

Is your water clear? If so, check to see how much FC your losing overnight. Test it in the evening after sunset, then again before the sun hits it in the morning. If you lose more than 1ppm overnight, then something is eating up the FC. In that case I would raise FC to shock level (15ppm FC given CYA of 40) and hold it there until you lose less than 1ppm FC overnight, CC is less than .5ppm, and the water is clear. During this process let the pump/filter run 24/7; keep an eye on filter pressure and clean when needed. Once all three conditions are met, then let FC drift down and maintain normal level (5-6ppm for CYA of 40ppm).

Hope this helps.