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gguff

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Aug 3, 2015
18
Aledo, Texas
I have a 40,000 IG pool. Builders initially forgot to install overflow pipe and with torrential downpours this spring in Texas the pool overfilled for several weeks and the filter quit cycling and had to be cleaned several times before the cartridges were eventually replaced. Needless to say we had an algae explosion. Got that cleared up and have been enjoying the pool ever since.

This AM results:
FC 0.4
CC 0.4
pH 7.7
TA 130
CH 450
CYA 80-85

We have been using chlorine tabs but even those haven't been keeping the chlorine levels up. Currently have blackish mold dots in the shallow end. Guessing the CYA level is so high because the pool company shocked it so much to get it back from the murky depths plus the pool tabs. I don't have any plans on replacing the water as I had it trucked in to the tune of $500/load.

Next plan is to shock with bleach today and tomorrow and turn off the pool tab.

Thoughts?

I also have an ozonater but i realize it doesn't do much during the summers here in Texas.
 
Welcome to TFP! Simply put, you'll need to increase your FC based on the Pool School - Chlorine / CYA Chart. You can also use the
Poolmath calculator to assist.

You'll use a bit more bleach with that CYA, but due to your well situation I suppose you don't have an option.


Oh, and those tabs/pucks raise your CYA as well. So you'll want to remove those right away. :)
 
Geez, I'm sorry. In my initial post above (edited) I got locked into your previously comment about green water. Disregard the SLAM if your water is clear for now. Simply increase the FC based on the CYA chart link above. Match your FC to the appropriate CYA level (Target or slightly above) and you should be fine for now. If the water should change later, then you may need to SLAM.
 
Thanks for quick response. So even if I have the blackish algae dots in the bottom of pool standard chlorine level will suffice? Water is crystal clear, but the little mold dots are persisting. Did an overnight chlorine loss test a couple nights ago and it dropped from 6 to 1.8ppm. Thanks in advance.

Grey
 
The loss of FC during your last OCLT confirms you have some algae stealing your chlorine. So in that case, a SLAM would be appropriate. Have you ever done a SLAM before? Here is the page: Pool School - SLAM - Shock Level And Maintain. Yes, regular bleach is what we use. Because of your high CYA, it will require more bleach (generic is fine), but that's better than taking a chance on getting replacement water with metals. Read the SLAM page carefully and do everything it states until you pass the 3 SLAM criteria. It will work. If after passing the SLAM, if you find that some spots are still persistent, we can readdress those areas specifically and a little more aggressively. If you have any more questions, please ask. Good luck!
 
Alright after 1 and 1/2 hours the fc dropped from 31 to 28. Added another gallon and 1/2 of 8.25% bleach. The fas/dpd test tube still had the tinniest bit of pinkish purple to it, so i went up to 70 drops from 56 and it never truly cleared, so I chose 56 drops when the first color changed. So 56 x 0.5 = 28
 
gguff said:
Alright after 1 and 1/2 hours the fc dropped from 31 to 28. Added another gallon and 1/2 of 8.25% bleach. The fas/dpd test tube still had the tinniest bit of pinkish purple to it, so i went up to 70 drops from 56 and it never truly cleared, so I chose 56 drops when the first color changed. So 56 x 0.5 = 28
Click to expand...
You could go down to a 5 ml sample and each drop will then count as 1 FC. It's not precise enough to do the overnight loss test, but it will speed up the FC test and save a lot of R-0871
 
Thanks for the info. I don't have a 5ml line but I do have a medicine cup I can use to put 5ml into the tube.

Last question for the night. Started this at 4pm, I know it can take days for a SLAM to pay off. Am I better to try and do an OCLT overnight tonight, or dump more bleach in than I need to keep the Fc high so I don't have to check it tonight but it stays high to keep the SLAM beneficial??

- - - Updated - - -

I should also add that I was gone from 6:30pm-10:00pm tonight and it dropped from 31 to 25, so not terrible, but still not stable added 3 gallons of 8.25%. I'll check the CC at 11pm
 

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Well my hope got the best of me and I ran an OCLT. Fc down from 31 to 22, but CC held steady at 0.5 so added 5 more gallons of 8.25%. Almost out of Reagent. Black spots seem to be fading. Have brushed the pool 4 times in the last 24 hours.
 
Agree, that is a lot of chlorine consumption, both last evening and last night. Brushing along with testing and adding chlorine every couple of hours are the two best things to do to speed up a SLAM.
 
hopped in the pool with goggles on. FC=30 found as many black spots as I could and scrubbed them off. The spots oxidize and turn a dull gray with violet/purple, but once you scrape them off there is green underneath. Hopefully that will do the trick. Been doing my FC samples this afternoon with 5ml as suggested to save reagent. averaging 31-34
 
Thanks. It's a pain in the arse, but worth it i think. Bottom of the pool is clean as a whistle and holding within 1ppm fc shock level every 2 hours in the hot Texas sun. maybe tonight is the night. If not the wife might kill me.
 
Last post for tonight. My FC test has been reading 30-31 all day. Ran out of reagent r-0871 on second to last test which read 30. Added 1/2 gallon 6% bleach to get me to 31. Rechecked 1 hour later with new bottle of reagent. Read 28.5?? Rechecked and read 28.5 again. Guessing some variation in the reagent?! What do y'all think?
 

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