Hello Forum.

We have a 14,000 gallon gunite chlorine pool. We have had trouble getting chlorine levels up and I believe it may be the chlorinator. It's the Pentair 300 Rainbow. Cylinder design. I found the lower elbow wasn't rattling when I shook it so I replaced that and I'm positive it's hooked up correctly.

My main problem is that if I check my chlorine in the morning it runs about 1-3 ppm. If I check it at night it runs about 0.3. I have a variable speed pump and I do run it at full speed in the morning and it drops to 1500 RPM when I check it at night. Could lit be that the higher RPM is pulling more chlorine through and then it drops as it goes through the day? Does the chlorinator need a certain RPM to function? I do notice that if I take the lid off the chlorinator while it's at 1500 RPM, there is no water in the cylinder but as soon as the lid comes off, it starts filling up. It is under pressure as I hear it depressureize when I open the lid. I'm just concerned that the "metered" valve on the side may be bad. Our pool looks great but I get worried when the chlorine is like 0.3 at night. Thoughts?