What chlorine level to shock -- now that half my CYA is gone

[JimK]

I need to print out that post about closing for future reference.

I'll check out that link also.

Thanks.

I'll report again tomorrow.

[JimK]

Day 2...

Hi Ben. I got the items you suggested (borax, OTO/Phenol Red test kit, 8.5% bleach - I have 19 jugs on hand now (121oz each).

I used the OTO kit to check CL and pH to see how it matched up with the Taylor kit.

FC - 0
pH - 7.2 (before adding borax; I'll test again in about an hour)

So it matches the Taylor kit results.

This evening I'll add the bleach as you recommended.

Is it OK to let the pool go all day with 0 CL???

[PoolDoc]

Probably be best to add 1/2 gallon or so.

[JimK]

Probably be best to add 1/2 gallon or so.

I'll do that right now.

[JimK]

I'm curious, with the initial dose of CL eaten up so quick, should I expect to see high CC? (I'm only seeing .5 max). Or does CC get eaten up some how as well?

[JimK]

.....
OK. Do this:

1. Use borax to push your pH to 7.8 or so.
2. Tomorrow PM late, add (10) gallons of plain bleach.
3. Test with OTO & phenol red in the AM. Add borax as needed to maintain the 7.6+ pH. Remember that phenol red will not return accurate results if the chlorine is very high.
4. Repeat this cycle till you can sustain a strong chlorine reading overnight.
5. At that point, you should resume using the K2006 testing.

....

Ok...here we go...did my homework for today.

Added borax this morning to raise pH
Per post above, added some bleach to carry it through the day since this morning's test showed 0 CL
Added 10 jugs of bleach about 8:30pm.

I'll give it about 1/2hr to mix then test to see if any CL shows up this time. I'll get up early tomorrow and test again.

Here's hoping.......

EDIT: Just checked CL using the OTO kit; sample turned dark orange....a good sign! We'll see what it looks like in the morning. Keep your fingers crossed.......

[JimK]

7am this morning (no sun on the pool yet) OTO test was still dark orange....yea!

Since I was still getting a strong CL indication with the OTO test, I also checked it with the Taylor kit and got this;

FC 25.5 (Taylor site says FAS-DPD can measure up to 20...the test behaved normally, so can I count on this result being accurate?)
CC 0
pH 7.6

So CL looks good, yes? I know high CL can cause inaccurate pH results, but this is real close to what I got when I checked pH before adding bleach (FC was at 0 at that point). Any chance this pH reading is good?

I'll check CL again after sunset using the Taylor kit, and if it's still at shock level I'll hold off adding anymore bleach and recheck early in the morning to see how much is lost overnight. Am I correct that if the loss is 1ppm or less I'm good to go?

At this point with the high CL level is it OK for me to test and start addressing TA, CYA, borates, and salt? Or do I need to wait until CL and pH are balanced first?

Sorry for all the questions. I realize this is a very busy time for y'all, but I'd really like to understand all this so I don't have to bug y'all again should the same situation occur again. With this knowledge I can contribute more/answer questions instead of asking questions all the time.

Thanks!

[PoolDoc]

Those chlorine levels indicate your chlorine demand is gone. Whether you have chlorine this PM will depend on how much sun you get today, and how much CYA is actually in your pool. BUT . . . you're on the home stretch here.

Take this opportunity (while chlorine is high) to brush your pool carefully in any spots where there might be slime, debris, or algae. You want to knock the goo loose, break it up, and then let the high chlorine wipe it out.

Once levels drop back to 10 ppm or so, do a full set of pool tests (FC, CC, pH, TA, CH, CYA) so you can see what 'tweaking' is needed.

[JimK]

Thanks Ben.

That's good news! So it ended taking 16 jugs of bleach total (about $50). Not too bad....I had fears it would be much worse!

Btw, this whole time since removing the cover Saturday, the water has been clear, and after vacuuming yesterday morning the pool looks great.

[Watermom]

Good job!