Do I have a bum regent?

[geempool]

I've been away for a week. Before I left, I started with a fresh batch of all new TF-100 refill regents. The day I left, I bumped the chlorine up to the highest swimmable level (9). Water was crystal clear, and swimmers reported everything was great while I was gone.

No one has been swimming or looking at the pool for the last two days. The pump was left off.

Now I am back. There are some leaves, the water is still clear, doesn't smell bad. I backwashed and turned on the filter.

I came back an hour later to test the water.

Doing the chlorine drop test, I got zero free chlorine or combined chlorine. Same on the chlorine box test. Not good.

So, I added 2 gallons of bleach according to the pool math suggestion, aiming for 7 chlorine.

Now, about 2 hours later, I still get barely 2 free chlorine, and .5 combined chlorine doing the drop test, but the box chlorine test seems to be reading much higher than 2 chlorine -- more like 5-10.

Should I add another jug and a half as suggested by the drop test, or is the chlorine likely actually higher as suggested by the box test?

Do I just need to wait longer to accurately drop test?

Are my drop chlorine regents malfunctioning? Or the box regents?

Thanks for any suggestions!

 

[ajw22]

Sounds like your pool got algae in it.

You need to follow the SLAM Process

 

[JoyfulNoise]

You should do an overnight chlorine loss test. If your pool’s FC was at zero for more than a few hours, algae can easily start to take hold. A pool can be clear in the early stages of an algae bloom. It doesn’t necessarily turn the water green or leave mats of green growth right away.