My stabilizer disappeared!

We have an auto cover and I hadn't opened the pool in a week. So, when I opened it, I noticed cloudy water like the start of an algae bloom. I tested the water and it showed 0 chlorine. So, I shocked and adjusted the SWCG up. A couple of days later, checked again and find 1.2 chlorine and 0 stabilizer. My stabilizer was at approx. 40 prior to this. I know we've had some splash-out (and one of my 2 year olds adjusted the valve on the filter and pumped about 15% of the pool water out), but I didn't expect it to be 0. The stabilizer I had used was a year old...any chance it went bad? I'm going to shock again and get the stabilizer level up, but I am curious as to why that happened. I think my TA is a little high also, but not sure how that might affect anything.

Levels as of today:
Chlorine: 1.2
Stabilizer: 0
pH: 7.4
TA: 250

Your TA is too high. Read about how to lower it and using muriatic acid safely here: http://pool9.net/alk-step and http://pool9.net/muriatic/

Turn your SWCG off for now. Shock the pool and keep it high until you can go from sundown one evening to within an hour of sunrise the next morning with no more than 1ppm of chlorine loss and you have no greater than 0.5ppm of CC.

Also, run your pump 24/7 while you are working to clear this up.

Thanks for the response. I'll work on lowering the TA. Is it safe to assume that a TA at that level will consume all of the FC rapidly? I shocked this morning with bleach and tested this afternoon only to find that the chlorine level at 0.

TA will not consume FC.

If you are losing chlorine fast it is because of one of two things.
1. You have no or little CYA and your chlorine is being lost to the sun.
2. You are fighting something in the water that is consuming the chlorine.

Are you using a Taylor K2006 to test? What does the water look like? What kind of filter do you have?

Yes, I am using the Taylor K2006 test kit. The water looks just a little bit cloudy, like there is the start of an algae bloom. I have a Pentair sand filter.

Ok. Same advice as in post #2 above. Since you had CYA of 40 and none now, you are going to probably need to add bleach a couple of times per day to maintain shock level. And, since it appears your CYA biodegraded, I hate to tell you, but it may take a lot of bleach to get rid of all of the byproducts left behind. Keep at it!

(To save your testing reagents, use a 10mL water sample when running your chlorine tests instead of a 25mL one. Multiply the drop count by 0.5 instead of 0.2.)

Keep us posted how things are going.

Thanks so much for the help. It appears that things are moving in the right direction. CYA is now present, though I ran out of reagent so I'm not certain of the level right now...gonna get some more. TA has come down to 200. Walmart hasn't run out of bleach yet, so I should be in good shape!

You are very welcome! Glad you are making progress!