Shocking story!


Active member
Apr 11, 2013
Long story short, I’ve been trying to shock my 40K gallon green pool that has not been closed with a looploc cover for at least 2 years. I bought the house last summer.

Anyway, I figured I’d shock with some diclor since the CYA tested 0, and some 12.5% liquid shock (details are below). But first I used a bunch of PH decreaser and some muriatic acid and ended up taking the ph down too far (to 6.5). I started anyway after this because I was tired of running out to get stuff.

I’m still getting a CYA of 0 and I don’t understand that. I’ve dumped a total of 8 lbs of diclor in so far and I thought that would have an effect?

Right now I’m wondering what my target FC should be and if I should be using diclor or liquid bleach?

Any advice would be very helpful!

Here’s my timeline:

1:12pm – Put too much acid in and took the ph from 9.7 to 6.5 (TA at 50)
1:55pm – add 13.5 lbs baking soda
2:38pm – test CYA and it is 0
2:46pm – test TA again and it is still 50
2:50pm – add 13.5 lbs baking soda
2:55pm – retest ph and it is still 6.5
4:49pm – Add 4lbs dichlor and 1 gal 12.5%
5:59pm – Test CYA still 0, fast test for FC 0
7:00pm – Add 2lbs diclor and 1 gal 12.5% - fast test FC=0
7:20pm – Add 2 gals 12.5%
8:00pm – fast test FC=0
8:20pm – add 2 gals 12.5%
9:00pm – add 2 gals 12.5%
9:47pm – DPD FC=9 and CC=4
9:50pm – Add 2 gals 12.5%
10:34pm – DPD FC=22 CC=5
11:51pm – DPD FC=19 CC=4
2:00am – DPD FC=11 CC=4
2:30am – add 1 gal 12.5%
7:34am – DPD FC=8 CC=4
Pool is now a green/gray color and very cloudy
10:27am – DPD FC=4, test CYA and it is still 0
10:45am – add 2lbc diclor and blue clarifier stuff
11:53am – DPD FC=8 (cloudy sky)
12:11pm – Test CYA and it is still 0


LifeTime Supporter
May 25, 2007
Round Rock, TX
I wouldn't worry about testing for CYA until after your done shocking. As long as you have CC you need to continue the shocking process. Go to, go to the bottom of the page and it will show you target FC levels.

You can also put in the dichlor you added and see if it was enough to measure



Mod Squad
TFP Expert
LifeTime Supporter
Apr 17, 2010
East Texas
Your 8 lb addition of dichlor has only brought your CYA to 12 so far. 12 is usually to small to register on a test I'd just get some powdered CYa from Walmart to bring it to 30 to help protect your FC and shock for that level of CYA. Don't bother to test for cya---won't show up yet. And I'd use the bleach for shocking and nothing else. I'd recheck your ph level while your FC is under 10 and get that fixed before continuing. Visit the chlorine/cya chart and the pool calculator in pool school.


TFP Expert
LifeTime Supporter
May 10, 2010
SW Louisiana
Assuming you started at 0 CYA, 8 pound of dichlor in a 40,000 gallon is only going to raise your CYA by about 10, since the viewtube CYA test only goes down to about 20 ppm, it is not surprising you don't see a difference.



TFP Expert
LifeTime Supporter
In The Industry
May 20, 2007
Key West, FL
Your target for shocking should be 10 until you get some CYA in there - I would use liquid unless you have the dichlor on hand already and want to use it up. Buying CYA separately would be cheaper than buying more Dichlor.

You likely had an ammonia in your pool. The huge chlorine demand and high CC readings are big red flags that you are breaking down ammonia.

Not sure if these will help you at this point but I'm virtually certain that is your situation.

Borax raises PH, not baking soda. Baking soda raises TA with a small affect on PH. Borax raises PH with a small affect on TA. Soda Ash or washing soda raises both quite well.


Active member
Apr 11, 2013
Thanks all!

I'll shoot for 10 FC then and use the dichlor I have, and go to wallmart tomorrow for cya. The ph is now 7, at a FC reading of 7 so I guess I'll leave that alone? I do have 5 lbs of soda ash I could dump in.

How long after dumping in a bag of dichlor should I wait before testing the FC?

One more... I got some 1" trichlor tabs and I have a floating dispenser. Should I set that up to go while I'm at work tomorrow?


Active member
Apr 11, 2013

From 6/1 to 6/9 I was shooting for FC of 10 but not multiplying the drops by .5 (Duh!) so while I thought I was at 10 I was really at 5. Ugg. Embarrassing...

I've added a total of 15lbs of trichlor and 6 lbs of dichlor (between 6/1 and 6/6) so theoretically my cya should be 34, but as of today (6/11) I can still see the dot with the tube full. It's a little hard to make out but it's there.

I'm now shooting for a FC of 12, and using 12.5 liquid shock. FC went from 14 to 13 last night, and tonight I measured a CC of .5. So I guess things are clearing up chem-wise, but the water is still really couldy. I can barely make out the bottom of the deep end. Looks blue it's just not clear. I tried 2 bottles of flock over the weekend and did a vac to waste Monday. I had that set up so I could see what was coming out of the pump since I could not see the bottom. Looked like I was getting a decent amount of gray green stuff at times during that process. After that I went back to running the pump 24/7.

Cleaning the sta-rite system 3 cartridges is a huge pain! I'm wondering now if the cartridges are bad? After cleaning I show around 28 psi and that goes up to 38 and then I clean them. They look pretty ratty. Any thoughts on that? It looks like it'll be at least 400 for a new set. At that cost I'm really tempted to just replace the whole thing with a DE that I can backwash.

Also wondering about my pool size. The pool store that was doing the maintenance for the previous owner has it on record as 40K, but when I add shock according to the pool calculator I seem to come out higher than I would expect. It's a freeform shape so not sure how to estimate. Does it make any sense to back-calculate the gallons from the amount of shock and delta in the FC?

Kinda bummed about the progress.

Thanks to all for taking the time to help me out with this.

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