I live in Portland, OR where we'll get a 90 degree hot day like today, then the temperature plummets to 60 for a few days or a week then maybe it gets hot again, or not. That means pool use is sporadic and because I've got an automatic cover the pool its only open the few hours its when actually being used. That means its pretty easy to keep the chlorine level where I need it because the only time it gets UV is when we're swimming. Even then it's only a couple of people in a 25,000 gallon pool so the load isn't very high. The chlorine rapidly goes to zero of course when the cover is open but I re-chlorinate when where done, close the top and the level stays pretty good, perhaps with a bit of topping up, until the next time I open it up.
I know it's odd but no CYA makes it easy to super chlorinate although we've never had to. No problems in more than 10 years. But when you only have 4-6 people using a pool and it's only for a couple of hours for a couple of days per month and the pool is constantly being cleaned with a pool robot there isn't much to get rid of.
I use liquid chlorine. Nothing else other than whatever I need to balance the pH and adjust Total Alkalinity and Calcium Hardness.
Good to know it's probably the test. Still showing 38 ppm when the real number is zero makes the test entirely useless. Weird, especially since every other time they've tested it's shown the correct number...zero.
