Speed of FC burnoff (sun)

[Aleforge]

My chlorine levels are sky high. And I was curious how quickly full sun + high temps can burn it off. Also does running the pump help, hinder or do nothing to speed up the process?

Thanks as usual!

 

[mknauss]

FC burned off to UV is essentially a percentage. Depending on lots of factors it can be 30-50% as an example.

How high is sky high versus your CYA?

 

[Richard320]

There are a couple graphs in this thread: Pool Water Chemistry
You might be able to decipher it if you're the science type.

Run the pump. The UV losses are greatest at the surface and diminish as you go deeper. So it's to your advantage to keep the water stirred up so it all has a turn at the surface.

Just out of curiosity, how high is "sky high" and how did it get that high? If it's at or below shock level for your CYA, it's okay to swim in and there's no reason to go to any extra effort to lower it.

 

[Aleforge]

I do not believe there is a way for me to check CYA as I have a K-1004 test kit.

I say "sky high" as the test goes off the chart. Here is a picture of the test i just did:
https://i.imgur.com/HGzzNal.jpg

It got this way due to me being an idiot. Several days ago my chlorine levels were around zero. It had been cool or a week and I wasn't paying much attention to things. During that time my chlorinator ran dry. So I added new pucks and cranked it up. It didn't help the next day much so I shocked it due to the algae that had grown. But I forgot about cranking up the chlorinator.... together my levels went into space.

Anyhow today we have friends coming out to BBQ and swim... In about 5-6 hours. So I was cleaning the pool and testing the water and sadness set in. PH is fine, the water is crystal clear but as you can see from the photo I feel like it's not safe to swim in.

The first thing I did was start cycling water out of the pool earlier today. But then realized that was pretty futile. It's already in the 90s and fully sunny... I think today is ruined so I was wondering if It could drop well enough for tomorrow or Monday at least. At least the kids would be happy.

I did end up getting a bunch of grass in it from mowing, LOL. Wonder if that will help.

Thanks guys.

EDIT: This is the shock I used, I do not believe it has stabilizer. Luckily as I usually buy shock with stabilizer.
https://i.imgur.com/tflzuvt.jpg?1

EDIT2: Is FC more important for swim safety than TC? I was assuming that FC is what I should always go by.

 

[mknauss]

That shock is Cal Hypo. It adds Calcium and chlorine. The calcium builds up.

You need a proper test kit. You must be able to test FC and CC. You must know your CYA to know what FC you need.

Order a TF100 test kit
The only other real option for a test kit is a Taylor K-2006-C. Be careful comparing prices because the K-2006 comes in sizes, designated by a letter. The basic K-2006 has .75oz bottles. You need to get the K-2006-C to get the larger bottles that you want. Even then it is a little short on the reagent & powder for the FAS/DPD test.

I also have the SpeedStir. It makes testing much easier.

 

[Aleforge]

Thanks MK, I will order a better one. So I am assuming that unless I can check the CYA levels there is no way to know how quickly the levels will come down? I also assume due to the test results that it’s too dangerous to swim in? Thanks again!

 

[Poolzzz]

Order a TF100 test kit
The only other real option for a test kit is a Taylor K-2006-C. Be careful comparing prices because the K-2006 comes in sizes, designated by a letter. The basic K-2006 has .75oz bottles. You need to get the K-2006-C to get the larger bottles that you want. Even then it is a little short on the reagent & powder for the FAS/DPD test.

The comparison chart shows the k2006C having exactly the same as the tf100 testkit. So if ones short on FAS/DPD they both are.

 

[mknauss]

The comparison chart shows the k2006C having exactly the same as the tf100 testkit. So if ones short on FAS/DPD they both are.

The K2006C is fine. Most people end up with the K2006 as it is cheaper. And it has small amounts of reagents.

- - - Updated - - -

Thanks MK, I will order a better one. So I am assuming that unless I can check the CYA levels there is no way to know how quickly the levels will come down? I also assume due to the test results that it’s too dangerous to swim in? Thanks again!

If you have very little CYA the FC will drop like a stone. But then you would normally never test FC in the water except for just after the addition of chlorine.

The issue is the FC/CYA ratio. That is what makes water safe or not to swim in. Minimum is 5%, maximum is 40% of CYA.

 

[Aleforge]

If you have very little CYA the FC will drop like a stone. But then you would normally never test FC in the water except for just after the addition of chlorine.

The issue is the FC/CYA ratio. That is what makes water safe or not to swim in. Minimum is 5%, maximum is 40% of CYA.

Ok so even with very high levels of FC if the CYA ratio is ok your good to go. What’s the deal with the calcium? I am not sure why the shock has it?

Also the PH level being balanced helps the effectiveness of the chlorine correct? If the PH is low does it slow down the burn up? I just had to raise it.

This sucks, I wish I owned the better kit. Throughout the day in full sun there hasn’t been much change. I wonder how many days this will take as the warm weather is adios Tuesday.

Thanks again!

 

[mknauss]

Chlorine is naturally a gas. So it must be 'attached' to something for us to use it.

Cal Hypo uses calcium.
Trichlor and Dichlor use CYA
Bleach/liquid chlorine use water. We like that.

Low pH make chlorine slightly more effective than high pH. But there is no effect to burnoff.

Get a proper test kit. So sad to miss out on the use of your big investment of a pool due to not having a $70 test kit.