Quote Originally Posted by danwann View Post
I had purchased a drop type test kit but couldn't read free chlorine (nor could my wife) so maybe there's a difference in kits
If you used an OTO (drops turn yellow when chlorine is present) tester, and your pool water sample did NOT turn yellow . . . you have no chlorine in the pool. OTO is not expensive, but it's extremely reliable: no yellow = no chlorine PERIOD. If you want to 'check' your tester, draw a gallon of tap water, add 1/2 teaspoon of bleach, mix, and test: you should see an orange sample result.

By the way, this is what an OTO/phenol red kit looks like:

and, if you click the picture, it will take you to a high quality (Taylor) K1000 kit. Shipping is as much as the kit, but if you can't find one that works locally, order that one.

If you were trying to distinguish "free" chlorine from "combined" chlorine . . . you're not ready to pursue that, yet.

Test strips are VERY un-reliable. Dealer read strips are sometimes more reliable, but stay away from BioLab stores if possible.

Stabilizer is, more or less, permanent UNLESS a biofilm (algae+bacteria community) develops that EATS stabilizer. You do NOT want this to happen, since the bacteria that eat stabilizer, often 'poop' ammonia, and it takes HUGE amounts of chlorine to get rid of the ammonia.

However, right now, we're still at square one: we need a valid OTO chlorine reading, and a valid phenol red pH reading!