Need help before draining

[rayh78]

Need help
Pool has been clear all year.
I have been using 3” tabs from Sams club.
POOLBRAND - Sodium Dichloro-s-Triazinetrione Hydrated=99% , 90% available chlorine
And
POOLBRAND Quick Dissolving Shock- Sodium Dichloro-s-Triazinetrione Hydrated=99% with 55.5% available chlorine.

Always clear and tested fine with about 1 tab a week in a floating chorlrnator
and then 1lb. shock every 2 weeks.
Vinyl pool 7500 gallons.

Anyway out of town weather got very hot and water got a cloudy. Tested and no chlorine.
Added 2 tablets and a ½ gallon of bleach
Added one pound package of shock twice after a couple of days.

Tested water and chlorine was good and started to clear just a little after a week.

Then tested again chlorine was low so add to more tablets.
After two days it is now very cloudy.

Took sample to pool store.
Free available chlorine = 5.77
Total Chlorine= 5.77
Combined= 0
Total A = 112
Calcuium Hardness = 54
CYA = 156


They say I need to drain pool and buy their chemicals. That the stuff from Sams has too much cya in it and that’s what caused my problem. They said mostly the Shock has too much CYA.

Neighbor uses same Tablets but uses Bleach for shock treatment. Should I do the same after I drain?

Thanks for any help

[aylad]

I see no reason to drain the pool--it is very easy to run a high CYA pool, you just have to increase your chlorine levels to compensate. See the "best guess chlorine chart" linked in my sig for more of an explanation, and the chart, but basically the dichlor powder and trichlor pucks you've been using do contain CYA, and it has gotten high enough that your chlorine levels need to be higher to keep algae away. With a CYA of 156, you just need to shock the pool to 25 ppm (I would use bleach for this) and hold it there until the water clears, and until you're not losing more than 1 ppm chlorine when measuring at night and again the next morning before the sun hits the pool. After you get to that point, let your chlorine drift back down to the 8-15 ppm range, but never below 8 ppm..or you risk another algae bloom. In 7500 gallons of water, each cup of 6% bleach you add will raise your FC by 1 ppm, so you can use that as a guide to know how much to add.

[rayh78]

Got home today and my son had drained and replaced 75% of the water with new.
Still cloudy but much better. Do I need to test first. Or could you make a guess on how much bleach I could put in tonight to get started.
Plan on taking a sample to pool store tomorrow. And ordering a better test kit.

Thanks for the help.

[Watermom]

Do you have a test kit of any kind now? If so, tell us what kind it is and then post results and then order a good kit!

[rayh78]

New readings but its still cloudy. Drained 75% and added 1 gallon of 6% bleach.
Should I just keep pump running and just wait? Lower PH some?

Thanks again

Free available chlorine = 7.6
Total Chlorine= 7.6
Combined= 0
Total A = 91
Calcuium Hardness = 45
CYA = 50

[aylad]

You don't list a pH reading, so I don't know whether it needs to come down or not. Since you've been using so much stabilized chlorine, though, I doubt it needs to be lowered. Chances are it needs to be raised. Can you test for that and list your result?

The next thing I would do is to test your chlorine level tonight, after the sun is off the pool, and test it again in the morning, before the sun hits the pool. Compare those readings, and if there's more than 1 ppm difference, then you need to shock the pool, which for a CYA =50 means you need to raise the chlorine to 15-18 ppm and hold it there until the water clears up and until you can run that test overnight again without losing any chlorine. If there is less than 1 ppm difference, then you need to keep your filter running and be a little patient to allow the filter to remove any junk from the water.

Do yourself a favor and get your own test kit and test your water yourself. Pool store test results are sometimes reliable and sometimes not, but there's no real way to know until you have water problems. We highly recommend the K-2006 linked in my sig, but for now, at least go to WalMart and get either the hth 6-way drop kit or the cheapie OTO kit (uses yellow and red drops for chlorine and pH) and use that. To determine chlorine demand overnight, you have to be able to get accurate testing done at specific times, and the pool store just won't be able to do that for you.


Janet