Total alkalinity vs adjusted alkalinity

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Rednekferlife101

0
May 15, 2018
10
Kutztown, pa
New member and first post! I’ve been watching the forum and got my tft kit and have been trying to keep my chemicals in balance but my pool is still cloudy... My pool numbers are:
CL-13
PH-7.6
CH-300
ALK-110
CYA-150-165ish

I took a sample to my local pool store and they gave me the paper back and it said my alkalinity then it said my adjusted alkalinity which was reflected from my cya number I googled it and it says adjusted alkalinity is your total alk. Minus 1/3 of your cya? Is that true? Do I need to raise my alkalinity up to be in range with my high cya number? I know I should drain the pool but this is my first house I just bought and first pool taking care of so I’d like to just use it this summer and keep my chlorine high for the cya being high and drain and refill it next year. Thanks!! Apprecite the help
 
Welcome to the forum! :handshake:

Trust your test kit. Do not go to the pool store.

FYI -- your CYA is too high to be sustainable. Do you have a plan to lower it?
 
Those numbers dont seem to be from the TFT kit. The CYA can only be measured up to 100, and pH will show 7.2, 7.5 & 7.8. I assume those are the pool store numbers. can you please post your TFT kit numbers.

But with that said, when your CYA gets over 100 it is super difficult to be accurate. MY best guess of your problem is that you have a huge CYA number, maybe even as high as 200 or 300, and you dont have nearly enough FC to keep your pool clean. Without seeing actual TFT hard to know, but I predict that you need to drain your pool down at least 50% and replace the water with new to get your CYA down to a normal number like 50 or 60.
 
So I shouldn’t take my tft kit alkalinity number and subtract 1/3 if my cya from it? And those are my tft numbers. My tft kit shows 7.5 ph but I got the digital ph meter which shows it’s at 7.6 ph. And for my cya I do half distilled water half pool water then double the cya number which is why I said it’s a broad range. The pool
store numbers are usually pretty close to my tft kit numbers except the cya theirs will be anywhere from 120-170 but they said over 100 their machine isn’t accurate. The pool stores adjusted alkalinity was 55 I believe it was. So they told me to raise my alkalinity but according to my tft kit my alkalinity is good! My water is cloudy though but that’s another topic... haha
 
You do not adjust the TA taken with the TF100 test.

It sounds like you did the dilute test for the CYA - correct? If so, a CYA of 160 will be quite difficult to manage. Your pH test will not be valid.

If you wish to try, keep your FC at 10% of CYA.
 
Thank you! Appreciate the help! Yes the cya was done with the dilute test! I want to wait to drain it because it needs some fiberglass repairs has some little cracks and chips around the edge and wanna make sure the whole pool doesn’t need to be redone before I fill it back up so if I can wait till the season is over I’d like to do that.
 
Your dilution idea is correct. But there are some accuracy issues with that dilution, so if you are not using a volumetric flask, then your 50-50 ratio might not indicate a perfect number.

BUt, with that said, here are your options. You can leave the CYA super high, but accept that it is going to be a royal pain to keep clear. And if you get a bloom, it will cost a fortune in liquid bleach to wipe it out. Your SLAM/Shock FC level will be about 65-70 if I had to guess. SO to go from 17 up to 65, you would need to add 10 gallons of 10% liquid. As the algae devours it in a bloom, my guess is that you will go through at least 40 gallons to deal with the bloow.

Other option, summer just started. I know you are in PA, so the season is short, but wait until sunday night, adn drain some gallons out. Maybe only half way. Then fill up. If you have a similar forecast to us with temps in the 90s for the next week, by next weekend your pool temp will be close to good, if not great. Water is somewhat low cost, so this would be cheaper than the excssive cya option, but of how you want. For that math, if you did half, you would use 10K gallons. The national avg per gallon cost is $0.006, so that would be $60 to replace 10K gallons.
 

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Yev said:
Your dilution idea is correct. But there are some accuracy issues with that dilution, so if you are not using a volumetric flask, then your 50-50 ratio might not indicate a perfect number.

BUt, with that said, here are your options. You can leave the CYA super high, but accept that it is going to be a royal pain to keep clear. And if you get a bloom, it will cost a fortune in liquid bleach to wipe it out. Your SLAM/Shock FC level will be about 65-70 if I had to guess. SO to go from 17 up to 65, you would need to add 10 gallons of 10% liquid. As the algae devours it in a bloom, my guess is that you will go through at least 40 gallons to deal with the bloow.

Other option, summer just started. I know you are in PA, so the season is short, but wait until sunday night, adn drain some gallons out. Maybe only half way. Then fill up. If you have a similar forecast to us with temps in the 90s for the next week, by next weekend your pool temp will be close to good, if not great. Water is somewhat low cost, so this would be cheaper than the excssive cya option, but of how you want. For that math, if you did half, you would use 10K gallons. The national avg per gallon cost is $0.006, so that would be $60 to replace 10K gallons.
Click to expand...

I have kept very high cya for many years with little issues. Just keep free chlorine way up like .075xcya.
Ph readings will be shot, so be careful about your readings . Cost is foo... I spend less than 100 bucks a year on chlorine. If you get a little spot of musturad algae then catch it early with very small amount of yellow treat. It’s cheep. Need to get good ph readings to keep chorine active to keep bad stuff in check.

Let them rip apart this approach :kim:
 
CaveDiver1932 said:
I have kept very high cya for many years with little issues. Just keep free chlorine way up like .075xcya.
Ph readings will be shot, so be careful about your readings . Cost is foo... I spend less than 100 bucks a year on chlorine. If you get a little spot of musturad algae then catch it early with very small amount of yellow treat. It’s cheep. Need to get good ph readings to keep chorine active to keep bad stuff in check.

Let them rip apart this approach :kim:
Click to expand...

So high CYA is 100 lets say. You keep your FC at 75 (.75x100).

I assume you meant .075. Also, Yellow Treat is either ammonia based or sodium bromide. Ammonia consumes large quantities of chlorine. Sodium bromide turns your pool into a bromine pool.

Good luck.
 
Good. Don't ever miss adding your chlorine. Also, Testing CYA to that level has about a +/- 25% error.
 
From Pool School

The precision of the test, when done correctly, is around plus or minus 15 for levels up to 90 and plus or minus 30 for levels between 100 and 200. Novices often have problems reading the test correctly, and tend to get higher than actual readings.

Once above 200 the error goes up again as you must do a further dilution.
 
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