White residue on salt water chlorinator cell

[PoolDoc]

I use a PentairPro II Test Lab to test the water and double check with the pool store now and then.

Ok, had to look it up. It's the old Rainbow kit. It should be better than strips, but I have no idea beyond that whether it's reliable or not. Because it's DPD tablets for chlorine, you can only test chlorine to FC or TC=5 ppm, and not very accurately at that. Also, because you just said "it's balanced and clear" without numbers, I needed to figure out what you were going by. It sounds like your following the test kit guide? We've never seen one of those (even the Taylor booklet) that was right.

So, do this:

1. Post your pool info to the chart (abt 30 seconds) so we have a clear picture of what you're working with

Pool Chart Entry Form
Pool Chart Results

2. Post your actual test results, for BOTH pool water and FILL water. (You only need to test pH, TA, and hardness on fill water)


For now, I'd turn off the cell, and chlorinate by hand.