Help with pool stabilization

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rdsantos72

New member
Jun 29, 2020
4
Middletown, MD
Hello there,
I am new to the forum and after reading a lot of the Pool School material and many of the posts, I am still a little confused about which step to take first to stabilize my pool water.
Our pool is 16,000 Gal. and we do have chlorine tablets and the Nature 2 express system as well.
We believe we are having a problem with what looks like black algae appearing in several places. They look like black circles.
Here are my current readings:
Results from poollogger.com
FC: 5.9
CC: 0.5
PH: 7.3
TA: 88
CH: 136
CYA: 119
Temp: 85
Borates:
CSI: -0.74

We use a ColoQ Pro11 test kit.

I've read about draining and replacing 40% of the water, using liquid chlorine instead of pucks, increasing the chlorine levels and etc.
I am just not sure which steps to take first.
Thanks for the help,
 
What test kit are you using? We need to make sure your numbers are accurate before proceeding. If they are, be sure to Read the cya/fc chart To understand what chlorine level is needed for elevated cya. Your cya is sky high and 5ppm chlorine will not adequately sanitize the water hence The problem with Alge. You are going to need to drain and refill the pool in order to get cya down to a manageable level As a 1st step. 40% won’t remove enough cya so calculate accordingly. Read the entire pool school and make sure you fully understand the risks with draining and refilling a pool in high water table areas first before undertaking that effort. once cya is in the 30ppm range the rest is easy. You likely will need to slam to kill the alge after the drain and refill so famaliarize yourself with that process as well. finally, unless you discontinue the use of tablets, you’ll be facing the high cya problem again in the future so plan on liquid chlorine going forward or possibly installing a swg.

there are plenty of folks to help you on here as you go along so be sure to ask questions when they arise and folks will be happy to guide you through.
 
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Thanks for the quick reply.

My test kit is a Lamotte ColorQ Pro11.
I've being using it for 2 years now.
This year we had very little rain in MD compared to the last two years. I remember having to drain water and refill again several times, which probably helped lower my CYA.

I will read about how to best drain the pool and go from there. I am hoping I can do it in stages, instead of all at once, let's see what I learn!
 
rd,

Welcome to TFP!

We promote a methodology that uses generic chemicals like liquid chlorine, muriatic acid, and a little CYA all from big box stores and at much lower cost than pool stores. For those that don't want to deal with "jug-lugging" we also promote salt systems. Both approaches avoid the CYA build you are dealing. And we do not use minerals due to the staining and other side affects. Please read ABCs of Pool Water Chemistry and ask any questions you may have. One thing to know is we don't sell anything so our advice is never conflicted.

I would quit using chlorine tablets and remove the mineral cartridge asap. Then do the drain or exchange to get your CYA in shape. Along the way we'll help you decide if you have algae or stains from the mineral cartridge and address as appropriate. I'll ask one of our experts that advises many people on transitions just like yours. @mknauss , Marty can you please weigh in?

I hope this is helpful.

Chris
 
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Welcome to the forum!
Others have guided you to the Draining article. If you are comfortable with the ColorQ test results you need a good 75% water exchange to lower your CYA.
Show us a picture of the black algae. If you can, scrape some of it off and smear it on a paper towel. It should smear green.
Eventually you need to get a FAS-DPD test kit so you can measure your FC more accurately.
I suggest you read ABC's of Pool Water Chemistry.
 
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mknauss said:
Welcome to the forum!
Others have guided you to the Draining article. If you are comfortable with the ColorQ test results you need a good 75% water exchange to lower your CYA.
Show us a picture of the black algae. If you can, scrape some of it off and smear it on a paper towel. It should smear green.
Eventually you need to get a FAS-DPD test kit so you can measure your FC more accurately.
I suggest you read ABC's of Pool Water Chemistry.
Click to expand...

Here are some pictures of the stain that we believe may be black algae. I've been brushing it, so that's why you see the smear color around the central black circles.
Brushing doesn't seem to do much other than create the smear you see.
I am not able to scrape any of it as you suggested. It's very thin and attached to the surface.
IMG_2325.jpg

IMG_2329.jpgIMG_2330.jpg
 

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rd,

No problem, as you've already seen we have experts that are "on the ready" to help. Also please be aware we have experts on virtually anything related to pools. If you have anything from an algae problem to equipment problem or even a pool construction problem we have an expert ready to provide straight up advice that's never conflicted. You may want to consider one of our recommended test kits as well. I believe we have at least one expert that uses the same one as you but I think he periodically verifies with a TF or Taylor kit. @Jimrahbe can you comment?

Please do keep us posted. If you have any questions or are not 100% certain about what to do we have your back!

Chris
 
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rd,

I have the ColorQ 7, not the exact one you have.. I use it a lot and like it, but... It is not as accurate as one might think.. I find it pretty repeatable, but it has a few issues with accuracy. I use it like you would a regular wrench, when I just want to make sure a bolt is tight.. But, if it is important, then I use my TF-100 as a Torque wrench.. Every month or so, I compare my ColorQ to my TF-100 and adjust how I use my ColorQ..

The ColorQ measures Total Hardness and not Calcium Hardness.. Depending on your local water there could be a 100 ppm difference between the two.

I find that the CYA measurement is often different between batches of tablets.. I had one batch of tablets that constantly read 30 ppm too high..

I find the pH reads low about .2 ppm, so 7.8 is really 8.0.. That said, I find it almost impossible to use the color match pH test that comes with the TF-100.. I can't tell the difference in shades of red..

The biggest problem with the ColorQ is that it will not test FC above 10 ppm.. In most cases this is not an issue, but if you are trying to do a SLAM with FC in the 30's it just does not work well.

Thanks,

Jim R.
 
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