CYA is 0 - Pool service says it's okay and left it at that.

BrentATL

Member
Jul 15, 2021
24
Homosassa, FL
Pool Size
10800
Surface
Plaster
Chlorine
Salt Water Generator
SWG Type
Hayward Aqua Rite (T-15)
Bought our new house with a SW pool and continued the pool service the previous owner had. Water was always clear and never saw any issues, but I wanted to learn how to take care of the pool too. Bought a TF-100 kit and started testing every few days. I thought maybe I was doing the CYA test wrong because it continued to be clear at the 20 mark. Had the pool lady (a new hire) check it as I watched her fill the CYA view tube all the way up and she said "it's low". She went to get Cyanuric acid and came back with the owner (sitting in the truck) and the owner said it was at 60. What?....I just watched her do it! She then continued to tell me it's not possible it's at zero because my FC is at 3.5 (which I confirmed in my tests) and if my CYA was zero, FC would be low.
Is this true? What should I do from here?
FC -3.5, pH -7.8, TA -50, CH -275, CYA 0, Salt 2900, Temp -89.
 
Your FC can be anything if your salt cell is generating chlorine, that won’t indicate the presence of cya. It’s just working harder to continually generate chlorine, thus shortening the life of the cell, because there is no CYA to protect the chlorinee from UV burn off. For a saltwater pool add stabilizer to get your cya up to 70. Then maintain your FC according to the CYA/Chlorine ratio chart. Your SWCG will thank you for it.
 
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Your FC can be anything if your salt cell is generating chlorine, that won’t indicate the presence of cya. It’s just working harder to continually generate chlorine, thus shortening the life of the cell, because there is no CYA to protect the chlorinee from UV burn off. For a saltwater pool add stabilizer to get your cya up to 70. Then maintain your FC according to the CYA/Chlorine ratio chart. Your SWCG will thank you for it.
Thank you!
 
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Fire your pool service company. You have the best test kit. You know your results of testing. Your service company confirmed the results and did nothing to fix it. What are you paying them for?

Buy some CYA and put it in your pool. You have a SWG, taking care of your pool should be easy.
 
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Your FC can be anything if your salt cell is generating chlorine, that won’t indicate the presence of cya. It’s just working harder to continually generate chlorine, thus shortening the life of the cell, because there is no CYA to protect the chlorinee from UV burn off. For a saltwater pool add stabilizer to get your cya up to 70. Then maintain your FC according to the CYA/Chlorine ratio chart. Your SWCG will thank you for it.
The SWCG doesn't work any harder with low CYA it's just the way it produces it at a very slow rate. The uv will kill off new FC immediately basically rendering the SWCG useless. The SWCG is a maintainer for once the FC is where you need it to be it'll keep it there assuming everything is in sync.
 
Fire your pool service company. You have the best test kit. You know your results of testing. Your service company confirmed the results and did nothing to fix it. What are you paying them for?

Buy some CYA and put it in your pool. You have a SWG, taking care of your pool should be easy.
I just needed time to get comfortable with testing and some more knowledge on how, why, when, and now that I have found this site, I think I'm ready to tackle the maintenance myself!
 
The SWCG doesn't work any harder with low CYA it's just the way it produces it at a very slow rate. The uv will kill off new FC immediately basically rendering the SWCG useless. The SWCG is a maintainer for once the FC is where you need it to be it'll keep it there assuming everything is in sync.
So question then: If my FC is at 3.5 (which looks to be on the high end...correct?), and raising my CYA levels, will the SWG reduce chlorine output (does it monitor chlorine levels) to maintain?
 
So question then: If my FC is at 3.5 (which looks to be on the high end...correct?), and raising my CYA levels, will the SWG reduce chlorine output (does it monitor chlorine levels) to maintain?

With 0 CYA your chlorine is very high. As you add CYA, you will adjust your chlorine level according to the chlorine to CYA chart (see pool school).

Your saltwater generator is a "dumb" device. It has no idea what your chlorine level is at any given moment. It will produce based on what you set it at (percent). It only runs when your pump is running too.

 
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No. It does not monitor FC levels. You will monitor them with your test kit. You will start by adding the stabilizer into the pool via the sock method. Then adjust your chlorine with liquid chlorine to hit your target. If CYA is 70, your target FC is 5. Then adjust the output of your SWCG to maintain FC of 5.
 
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You monitor chlorine levels... Once you get your CYA to 70 bring your FC to 6 (i have mine at 7) and let your SWG maintain that...

How do you do that you ask :)

What size is your SWG? run it at 100%

Pick a time to run the pump and SWG, say 8 hours... 24 hours later or when you check FC the next day is the FC still at 6? if it is that is how long you need to run it for...

After that you can change it up...

run the SWG at 50% and run the pump for 16 hours... or 24 hours at 45% SWG... or keep iy at 100% for 8 hours.. all 3 use the same exact amount of the SWG but 2 cost more to run a single or 2 speed pump.. if you have a VS pump all 3 will work :)
 
How do you do that you ask :)

What size is your SWG? TCELL940 (Is this the size?)
Haha...I was going to ask!!
That makes sense.
I am running my pump 12 hours a day (up from 10 hours per pool store recommendation). If I understand this correctly, once I get my FC to 6, adjust the SWG output to maintain 6. If I drop back to 10 hours a day, the SWG % may need to be bumped and FC's verified to find the "happy spot". Correct?
 
You are all over it... test and correct, that is what it is all about...

You will need to change the SWG % or run time about 3 times a year... lower in spring, higher in summer and lower in fall... :)
 
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If they will just lie to you about the CYA, what else are they lying about?

This is more than incompetence, it's just dishonest.

Fire them and do it yourself or at least get someone honest and competent.
Good point. I'm taking it over and appreciate everyone's help here!
Another question....I watched the girl rinse out the test containers in the pool. Is that okay?
 
See, you already know more and are doing a better job than your pool service.

Just one small clarification. Dont use your SWG to raise you FC level. Use Chlorine to do that. You set the SWG to maintain the level once you have it there.
 
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