Pool newbie - can't keep FC levels up

threegraces

New member
Jul 7, 2020
2
MN
Hi - like everyone else trying to keep kids entertained during the pandemic, we bought a 12' round Intex pool. I feel like I'm constantly having to add more chlorine. I have a floater with 3 mini tabs and I feel like I'm adding "shock" level chlorine every few days. Is this normal? I use test strips and typically the TC and FC are close to balanced but the FC always drops first. Is this normal? It is ~1700 gallons and the water is nice and clear and gets at least 5 days of use per week by my kiddos. It gets full sun from 10 am to 5 pm and runs around 90 degrees. The pH is always on the high side because we have very hard water where I live (12 year water heaters last 5-6 years). We run our pump 24/7 mostly because I would probably forget to turn it off and on. Thanks!
 

kevinskii

Gold Supporter
Aug 6, 2019
94
Los Angeles, CA
Hello there. I think the general advice on this site is to avoid using pucks to chlorinate the pool (see "how to chlorinate your pool" for a summary of reasons why) and stick with liquid chlorine. What you're seeing seems to be in line with this.

It sounds like you're doing a good job keeping the pool safe. While you continue with your current process, please consider replacing your test strips with a proper test kit. The TF-100 on tftestkits.net is probably the most popular choice on here, with a close second being the Taylor K-2006C which you can get on Amazon or various pool sites. Your test strips probably won't be able to test your cyanuric acid (CYA) or combined chlorine (CC) levels, and the accuracy of the other tests will also probably be less reliable than a drop kit.

From what you describe, you likely have very low CYA which is causing the sun to burn off your chlorine quickly. The good news is that once you get it up to the recommended level, it tends to stay there for a few weeks. Then you'll probably just have to add a bit of liquid chlorine every day or so.
 

threegraces

New member
Jul 7, 2020
2
MN
Hello there. I think the general advice on this site is to avoid using pucks to chlorinate the pool (see "how to chlorinate your pool" for a summary of reasons why) and stick with liquid chlorine. What you're seeing seems to be in line with this.

It sounds like you're doing a good job keeping the pool safe. While you continue with your current process, please consider replacing your test strips with a proper test kit. The TF-100 on tftestkits.net is probably the most popular choice on here, with a close second being the Taylor K-2006C which you can get on Amazon or various pool sites. Your test strips probably won't be able to test your cyanuric acid (CYA) or combined chlorine (CC) levels, and the accuracy of the other tests will also probably be less reliable than a drop kit.

From what you describe, you likely have very low CYA which is causing the sun to burn off your chlorine quickly. The good news is that once you get it up to the recommended level, it tends to stay there for a few weeks. Then you'll probably just have to add a bit of liquid chlorine every day or so.
Thank you so much for your response. There is so much conflicting information on what you need to have - I didn't know that about the tablets. I just thought - wow, CYA and chlorine together - perfect! My test strip does show CYA and it generally runs around the 30-50 range (that is the printed range). I will try removing the pucks and stick with just liquid chlorine.

Would the hard water and generally high pH also be a problem? I got it down with a healthy dose of pH lowering (after several cautiously applied smaller doses). I want to keep the pool safe for the kids without burning their eyeballs :)
 

kevinskii

Gold Supporter
Aug 6, 2019
94
Los Angeles, CA
I don't think the hard water will be much of a problem, especially for an Intex pool. You'll probably want to keep your pH in check mostly for your kids' comfort to prevent eye irritation. The best way to lower it is with muriatic acid, which you can buy in any hardware or big box home improvement store. It's pretty nasty stuff on its own. Be careful to store it away from your other chemicals, and do not add it within 10 minutes of adding liquid chlorine. The two will form a toxic gas if they combine. Don't allow the kids to swim until at least 10 minutes have passed since you added it. A little bit goes a long way. I have an 18k gallon pool and it only takes about 1.25 cups of acid to lower the pH from 7.8 to 7.6.