Like many other on here I am fighting a high CYA (Over 100). Pool math says replace 50% of the water which just isn't reasonable. Is there another way to get it to lower? Would something like baking soda help it? What causes CYA to increase? As a result I am fighting a cloudy pool. All my other numbers are good. Any help is appreciated. Thanks.
CYA: How do I lower without replacing water and what causes it to rise?
- Thread starter Vtfanatic
- Start date
Using pucks, (tablets), or most bagged "shocks" will raise your CYA. I see from one of your previous posts that you were at a CYA of 80 about 3+ weeks ago. Did you add any pucks or shock?
You have about one option for lowering your CYA, replace a significant portion of your water.
CYA can be removed by reverse osmosis filtration but that is really only an option in select few areas of the sun belt and an expensive option when it is available. Pool store voodoo chemicals promising to lower CYA have not proven to actually work.
You can maintain your pool with high CYA, but it will be tough. If your pool turns it will be difficult to even impossible to maintain the FC level you need to clear it.
Your FC level must be maintained at a much higher level to offset the high CYA. You will need a quality test kit to accurately test the high levels you will need to maintain, as you can find your level by looking at this chart. Assuming your cya reading is accurate, you need to aim for 12 ppm FC and never let it get below 7. If you are showing a level of 100 cya, unfortunately it is likely much higher, possibly well off the scale, even double or triple as we often see on this site.
The reason is simple, tablets and dry shock products add CYA with every tablet and every bag. It accumulates and stays in the pool long after the chlorine is consumed and gone.
You must stop using those products immediately and switch to bleach or liquid pool shock. Elevate your FC level and get a recommended test kit on the way.
Most TFP users dose their pools daily with plain household bleach or liquid pool shock. These are the same product, pool shock is slightly more concentrated. You can use the poolmath link at the top of the page to calculate how much you need to add to reach the correct level. Test each day and add the required amount to get back to target level.
A TF100 or K-2600 test kit is imperative, both to get a CYA reading and to test and maintain the high FC level accurately. CYA will reduce over time with dilution from rain, splash out etc. Evaporation does not help to lower cya.
CYA can be removed by reverse osmosis filtration but that is really only an option in select few areas of the sun belt and an expensive option when it is available. Pool store voodoo chemicals promising to lower CYA have not proven to actually work.
You can maintain your pool with high CYA, but it will be tough. If your pool turns it will be difficult to even impossible to maintain the FC level you need to clear it.
Your FC level must be maintained at a much higher level to offset the high CYA. You will need a quality test kit to accurately test the high levels you will need to maintain, as you can find your level by looking at this chart. Assuming your cya reading is accurate, you need to aim for 12 ppm FC and never let it get below 7. If you are showing a level of 100 cya, unfortunately it is likely much higher, possibly well off the scale, even double or triple as we often see on this site.
The reason is simple, tablets and dry shock products add CYA with every tablet and every bag. It accumulates and stays in the pool long after the chlorine is consumed and gone.
You must stop using those products immediately and switch to bleach or liquid pool shock. Elevate your FC level and get a recommended test kit on the way.
Most TFP users dose their pools daily with plain household bleach or liquid pool shock. These are the same product, pool shock is slightly more concentrated. You can use the poolmath link at the top of the page to calculate how much you need to add to reach the correct level. Test each day and add the required amount to get back to target level.
A TF100 or K-2600 test kit is imperative, both to get a CYA reading and to test and maintain the high FC level accurately. CYA will reduce over time with dilution from rain, splash out etc. Evaporation does not help to lower cya.
The OP has a TF100.
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Vtfanatic: please fill out your signature by clicking strings at the top of the page and then clicking edit signature on the left. Include your testkit. Thanks.
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Vtfanatic: please fill out your signature by clicking strings at the top of the page and then clicking edit signature on the left. Include your testkit. Thanks.
Thanks gang. I have the TF-100. It looks like the pucks may be the problem. The other thing I did is it sounds like I compounded the problem by doubling up the pucks while I was on vacation. That explains my problem. So do I just quit using the pucks and then let things settle out? Also I am getting ready to go on vacation again in a few weeks. Do you recommend doing anything prior to leaving?
How far over 100? I managed to survive 300- it just takes patience, brushing and filtering. And your pool needs to be clear to begin with. I wouldn't make it if it was green from the start.
Excellent!
OP, please add some details about your pool and include your test kit in your signature, very helpful for the folks trying to help.
OP, please add some details about your pool and include your test kit in your signature, very helpful for the folks trying to help.
- May 22, 2013
- 2,796
- Pool Size
- 12000
- Surface
- Plaster
- Chlorine
- Salt Water Generator
- SWG Type
- Hayward Aqua Rite (T-15)
I would remove them immediately, they are only contributing to the problem. Be aware you will need to dose daily with bleach or liquid shock to maintain your FC level.
You really must get that FC level up to 12 and keep it that high until your CYA reduces.
BRUSH, BRUSH, BRUSH! you really don't want the pool to turn green, it will be tough to recover from.
Do you have someone who can dose the pool for you while you are away?
I may possibly have someone. pucks removed. How long am I looking at to see my CYA start to fall with using the liquid bleach?
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pool math says I would need to drain half of my pool.
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pool math says I would need to drain half of my pool.
- May 23, 2015
- 24,403
- Pool Size
- 16000
- Surface
- Plaster
- Chlorine
- Salt Water Generator
- SWG Type
- Pentair Intellichlor IC-60
Why is replacing water not practical? Are you on a well? Municipal water supply restrictions?
If replacing water in a large quantity is not an option, then you can do it slowly by substitution - use your pool water to irrigate landscaping (do you have a big lawn that uses a lot of water?) and then fill the pool back up with water that you would normally send to your landscaping.
The only way to lower CYA is through water replacement (pool water exchanged with fresh water, evaporation does not count) so you have to figure out the best way to do that. Small serial dilutions will take a lot longer and use more water than doing one big water exchange, but sometimes you can only work with what you have...
If replacing water in a large quantity is not an option, then you can do it slowly by substitution - use your pool water to irrigate landscaping (do you have a big lawn that uses a lot of water?) and then fill the pool back up with water that you would normally send to your landscaping.
The only way to lower CYA is through water replacement (pool water exchanged with fresh water, evaporation does not count) so you have to figure out the best way to do that. Small serial dilutions will take a lot longer and use more water than doing one big water exchange, but sometimes you can only work with what you have...
It depends on the weather, The only solution is dilution! You need rain, or lots of backwashing, splashout and refills if you want to bring it down naturally.
ok, a big mass deduction and refill would take a long time especially with kids and not to mention my water bill. I guess I will do it incrementally which I started doing earlier today anyhow.
CYA does slowly break down over time through oxidation, the bad news, is it does so very slowly, think years not months, so again water replacement is the only practical option.
If you can use some of the pool water for other purposes, backwash a little extra long, hope for the rain and drain scenario, cya will work it's way down, but it takes time and overall you will use far more water than a large water change all at once.
I would invest significant effort to make sure the pool does not turn green. Diligent testing and dosing to maintain the FC at 12, along with regular brushing and vacuuming.
Your bleach usage might make the water bill look cheap if you have to reach shock level and hold it for several days.
I would invest significant effort to make sure the pool does not turn green. Diligent testing and dosing to maintain the FC at 12, along with regular brushing and vacuuming.
Your bleach usage might make the water bill look cheap if you have to reach shock level and hold it for several days.