My tub has chlorine lock ... I had it on my last water change and it was determined by Stuart - Thanks Stuart!!
But, I have new water about a month old and it seems that it has developed it again.
What can be the cause of it?
I use dichlor, run ozone 10 hours a day and my when my tub clears it's pipes I have it injecting air. I do use a foam thermal blanket and the tub only gets used once or twice a week.
To give an example of what's happening - I used the tub last night, soaked for about 50 min and added what should have been 2 PPM (even if I slipped, it would be 3 PPM). Now 20 hours later I have 3 PPM chlorine verified by 2 test kits.
I'm at a loss at what's going on unless my tub is the most cost effective tub in the world when it comes to chlorine ... or maybe it thinks I'm putting in bromine!
As long as I'm not doing any damage to the tub, I really don't care but would like to know, at least I don't have to worry about bacteria!