New convert with high CYA

[HM5]

I have been using 3" Trichlor tabs in my Rainbow chlorinator and performing my own testing with a basic 4 kit for the five years we have owned our pool. Last summer was the first time I've had algae issues, thanks to a complete drain and refill for a pool remodel several years ago that kept the CYA in check for a time. I took my water to the pool store multiple times for testing and received a different answer each time regarding the cause of my algae. Thankfully I found this site and figured I must have high stabilizer levels and would need to do a partial drain to remedy. But with a new baby joining our family last summer I wasn't prepared to deal with it, so here I am.

I just received my TF100 kit and performed the first tests today. The water is clear with a tendency for algae in the corners of the steps and on the Polaris bag. My results are:

FC 2
TC 2
pH 7.6
TA 90
CH 500
CYA 130

My question is this:

I know I need to do a partial drain and refill to get both the CYA and CH in check, but we will be out of town for two weeks at the beginning of June. Do I do the drain and refill now, start chlorinating with bleach, and then use tablets while we are gone? I don't know how else to chlorinate the pool while we're away. Will two weeks use of tablets raise the CYA back up by much?

 

[JohnT]

Welcome to TFP!

How many tablets a week do you normally use?

 

[HM5]

On the current settings, 2-3 tablets per week. I want to start using bleach to chlorinate and give up the tablets, but wondering if I should just wait until we return from vacation to make the switch...

 

[JohnT]

Two weeks will probably give you an increase of about 15ppm CYA.

 

[HM5]

Okay, so I will drain more than the recommended 69% to make up for the 15 ppm gain. Any recommendations for submersible pumps for the drain? Rent vs. buy? Brands?

Thank you for the help!

 

[Casey]

No one can answer on whether you should rent or buy but you're doing the right thing by getting the CYA level down now before you leave. You could always SLAM the pool and cover it with a solar cover (of course after the drain/refill). A lot of people do it that way too.

Welcome to TFP and congrats on the kit and taking control of your pool by using TFPC.

 

[HM5]

Update:

I drained 80% and refilled the pool. I just turned the pump on, thinking I need to run it constantly for awhile...? Here are the new test results:

pH 8.2
FC 0.5
CC 1.5
CH 225
TA 100
CYA 25 (yay! Much better than 130!)

I leave in one week for vacation, the CYA level will increase a bit then since I will use tabs while away. I know I need to add bleach to get rid of the CC and increase the FC, add acid to decrease my pH, and add something to increase my CH (will need to purchase this, have never had to increase CH before). What do I do first?

 

[timerguy]

Time to use those tabs to get your cya back up a little. 30-50 is a good range. You'll need to get your FC up too. Use some bleach to initially get it up then let the pucks do their job.

 

[jmbradwell]

Drop the pH with some MA, and use the pucks to bring your chlorine and CYA up.

 

[JVTrain]

I would get your CYA up to 30. So not much. While raising CYA, SLAM the pool following the instructions here: SLAM. You'll need one of the recommended test kits with a FAS-DPD chlorine test to complete it properly. I'd recommend the TF 100. With the SLAM, adjust pH first, then start maintaining shock levels of FC with liquid bleach.

Then when you're gone, you can use the tablets and your CYA should be in the 45-50 range, which is a bit high on the 30-50 scale but being in Houston, you likely get quite a bit of sun so a little bit higher CYA is OK. If you just use bleach to chlorinate after that, you'd shouldn't have a problem.

 

[duraleigh]

and add something to increase my CH

I would suggest you leave your CH alone. It is borderline low and will creep slowly upward over the season. You will probably be at 250 soon enough and maybe 300 by seasons end.

If your water is clear, I would suggest an elevated FC level of about 10 ppm FC but not a complete SLAM. I think that will drop you CC's down to .5 ppm or less in a day or two.

Report back that your water whether your water is clear or not.

 

[HM5]

Water is clear and sparkling! Have tested and added bleach several times since last night, only added enough to bring my FC to recommended normal level 2-6 ppm, not SLAM levels. CC is now at 0.5, FC at 2 ppm, pH 7.6. I used more bleach than I would have guessed I would need, 2 gal. of 10%. I went ahead and put one trichlor tablet in my chlorinator to raise my CYA a bit. Thanks for all the input! I will leave my CH alone, was wondering about that myself since we have very hard water here.

 

[HM5]

- - - Updated - - -

 

[jmbradwell]

Nice Pool. Whens the BBQ?

 

[HM5]

Ha! As soon as the water is warm enough to tolerate! Did the overnight chlorine loss test last night and only lost 1 ppm, CC still 0.5. Can I start testing and adding bleach just once a day now?