I replaced my liner this year and installed a rainbow 320 chemical feeder. I'm having issues with my sanitizer levels (they consistantly remain around 0 ppm) when using the feeder. I started with bottom feed wide open to no avail. I now have it set up for top feed with valve wide open and still nothing. Here are a few observations.
1. Direction arrow is pointing in the direction of the flow (so feeder is installed in right orientation)
2. With cap off, no water flows through valve when closed and increases as valve opens
3. Tablets are eroding
4. When the pump is shut off, the feeder does not drain until the cap is removed.
5. Tested feeder without cap off, valve closed, and pump running for 15-20 seconds. Wated did not enter feeder until I opened valve.
6. Filled feeder about 3/4 of the way, with cap off, to see if feeder would drain. Could really tell much so I left it for about 5 hours with cap off and pump running. Came back and the feeder was filled all the way to the top.
7. Pressure running between 25 and 30 psi (pump and filter original, sand replaced 3 years ago before we acquired the home so I don't know what start up pressure was).
So, two questions. First, could the line pressure be keeping the feeder from draining? Second is why is the feeder filling with water when the valve is shut? Thanks in advance from a pool newbie!