High CYA

[scall77]

Bought a new house in June and I've been struggling to keep the pool reading chlorine levels. Pool stores were no help so far except of selling chemicals that did not work.
Just received my new TF-100 kit and the results so far are enlightening.

Stats with the new TF-100 so far:
FC 1
CC 1
TC 2
CYA 100-110
PH 7.2

Old owner used clorox pucks and clorox shock(1-2 bags a week).

I'm assuming the high CYA is causing my chlorine issues. Green algae is now also blooming in the pool.

Is my only remedy at this point to drain water from the pool and reset and then SLAM? (PoolMath seemed to indicate 60% of the water would need replaced. Ugh.)

Thanks for any help or advice.

 

[Texas Splash]

Hello and welcome to TFP! You are correct! Best way to lower CYA is a partial drain/water exchange. I would shoot for a CYA target of 40-50 so that you're ready for summer afterwards. Good thing you have that TF-100 now. Do the water exchange first before wasting chemicals in the water. Start with a new CYA number and SLAM away. Nice to have you with us.

 

[max2k]

how expensive would it be to replace half of your water? It's the best thing you could do, don't get me wrong but you need to take your local water price / policy into consideration. Around here that volume would run me about $60-$80 which I'd consider acceptable as long as there's no fine on top of that.

 

[scall77]

Thanks for the quick replies!

I'm on well water so the expense isn't a concern. Guess I know how I'll be spending the weekend.

 

[robertmee]

First things first....to get a cya over 100 you would have to have done a dilute test....half of the pool water and half tap water and then multiply by 2....but since there is no 55 on the test vial, 110 wouldn't be correct even if you did the dilute test. So if you're going to go through the trouble of a drain you really need to nail down your Cya value first. Can you confirm you did a dilute cya test or are you guessing that it's something over 100? The reason it's important is because if it's something over 100 and it's really 200 then multiple partial drains or a full drain will be in order.

 

[scall77]

I got my readings from the CYA black dot test that came with my TF-100. Performed the test 3 times. Half Pool water and Half R-0013. On the "CYA VIEW TUBE", the marks go to 100 and the black dot was disappearing a couple cm's under the 100 marking.

 

[Kiss4aFrog]

Welcome to TFP scall77

 

[robertmee]

Okay so it's a 100...not 100 to 110. Don't mean to be a stickler but it's important to accurately report test results. When 110 is used it sends up a red flag and better for us to question and get clarification so we can help you the best.

So you have two options for drain..you can do a 70% drain and fill giving a refill cya of 30 and you can do a slam with a target FC of 12. After slam you can add some stabilizer to get your CYA up to 40 or 50. Or you can do a 50% drain and refill which will put your Cya at 50 but then your slam FC will be higher so you'll use more bleach to complete your slam. 6 one way half a dozen the other.

 

[scall77]

Absolutely. Better to be sure before attempting something like a drain. Appreciate all the help everyone.

 

[max2k]

Absolutely. Better to be sure before attempting something like a drain. Appreciate all the help everyone.

how deep is your water table? When you drain the water you want to make sure its level doesn't go below natural water table level around your pool or it might 'float' leading to really costly repairs. Don't want to scare you, just checking for unusual condition. You probably can estimate that by comparing water level in your well and in your pool if they're located nearby.