Need some help please, I have a 16,000 gallon pool that was recently drained in May 2022. Professional company restarted chemistry, I maintain. I use about 1-2 tablets of Leslie's chlorine tabs a week. I test for ph, chlorine, and alk weekly. I add muriatic acid weekly for high ph, I have a water feature. I also add about 5 lbs of bi carb every two weeks to counter the alk drop from the acid. I typically have high ph and low alk. I also do a weekly phos dose given lots of debris in pool. In about 90 days the CYA has gone from 30 ppm to 100ppm. Test info from pool store may be an issue, but magnitude and direction of increase is concerning. What could cause CYA to spike that quickly. It hurts my gut to think about having to drain the pool after just doing that. Hoping to find root cause if possible.
Rapid CYA increase
- Thread starter mstarace443
- Start date
Hey M and Welcome !!! Check the ingredients on your tabs. Cyanuric Acid will be listed and each tab adds some CYA. As you've found out, they aren't sustainable.
The good news is, that the pool store gets that test wrong the most of all their wrong tests. Get yourself a test kit that will keep you out of the pool store. We'll tell you what to add on the cheap, and you'll have the clearest water in your neighborhood.
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The good news is, that the pool store gets that test wrong the most of all their wrong tests. Get yourself a test kit that will keep you out of the pool store. We'll tell you what to add on the cheap, and you'll have the clearest water in your neighborhood.
How Clear is TFP Clear?
Pool Care Basics
Test Kits Compared
- Jun 24, 2021
- 7,495
- Pool Size
- 30000
- Surface
- Vinyl
- Chlorine
- Salt Water Generator
- SWG Type
- CircuPool RJ-60
Hey! Welcome to TFP!!! 
@Newdude has you covered on the CYA.
The higher the aqueous (dissolved) CO2 levels in the pool, the faster pH will rise. Lower pH water has higher levels of CO2. Higher levels of TA allow higher levels of CO2. When pH is low AND Total Alkalinity is high, the pool has the highest levels of CO2, resulting in the fastest pH rise.
Sooo, as a result, when you lower your pH (add acid) and raise your TA (add bicarb), you will see more rapid pH rise.
If you can, run your water feature less, and keep your TA around 60. Also, your pool is just fine with pH of 7.8-8. You may find, with TA ~60 and pH 7.8-8 (even 8.2), your acid dosing and bi-carb additions will decrease. Try it, it will reduce the yo-yo you are swinging with Acid and Bi-Carb.
I'm assuming Phos-Free or no Phos etc? These product not only have the lowest concentration of lanthanum chloride in it, it also contains a simple polymeric clarifier in it. This can result in white precipitate and cause your filter pressure to rise more than normal. I would stop using it, and clean your filter. Will cost you less $$$ too...
@Newdude has you covered on the CYA.
CO2 outgassing is the cause of pH rise. The water feature (aeration) accelerates CO2 outgassing, raising your pH.
The higher the aqueous (dissolved) CO2 levels in the pool, the faster pH will rise. Lower pH water has higher levels of CO2. Higher levels of TA allow higher levels of CO2. When pH is low AND Total Alkalinity is high, the pool has the highest levels of CO2, resulting in the fastest pH rise.
Sooo, as a result, when you lower your pH (add acid) and raise your TA (add bicarb), you will see more rapid pH rise.
If you can, run your water feature less, and keep your TA around 60. Also, your pool is just fine with pH of 7.8-8. You may find, with TA ~60 and pH 7.8-8 (even 8.2), your acid dosing and bi-carb additions will decrease. Try it, it will reduce the yo-yo you are swinging with Acid and Bi-Carb.
Phosphates are not a problem in a pool if you maintain appropriate FC levels. (see this page --> FC/CYA Levels
I'm assuming Phos-Free or no Phos etc? These product not only have the lowest concentration of lanthanum chloride in it, it also contains a simple polymeric clarifier in it. This can result in white precipitate and cause your filter pressure to rise more than normal. I would stop using it, and clean your filter. Will cost you less $$$ too...
- Jun 1, 2018
- 13,562
- Pool Size
- 26000
- Surface
- Vinyl
- Chlorine
- Salt Water Generator
- SWG Type
- Hayward Aqua Rite (T-15)
Here’s what each dissolved 8oz tab does to your water 
2 tabs per week for 12 weeks comes out to about 50 ppm of cya they have added to the water.
The 1st step is getting your own test kit (taylor k2006c or tf100/pro) & knowing your actual cya along with the other values.
Your pool also needs to go on the liquid diet ASAP —-> liquid chlorine.
Follow the FC/CYA Levels so nasties don’t grow.
www.google.com
2 tabs per week for 12 weeks comes out to about 50 ppm of cya they have added to the water.
The 1st step is getting your own test kit (taylor k2006c or tf100/pro) & knowing your actual cya along with the other values.
Your pool also needs to go on the liquid diet ASAP —-> liquid chlorine.
Follow the FC/CYA Levels so nasties don’t grow.
How to Chlorinate Your Pool
Before chlorinating your pool, you should know these simple tips. Learn the best way to add chlorine to your pool.
www.google.com
Thanks for the great insights. I've got my k2006c on order. Unfortunately I can't run the water feature less, it's the spa waterfall into the pool. But I definitely see what you're saying on being ok with the slightly higher ph and slightly lower alk.
As far as the chlorine, I'm just baffled. I'm for sure switching to liquid now. At my prior house, I had a 30,000 gal pool with a steady diet of the Leslie's tabs after reading the "off brand" issues. Never had a CYA issue. I do see the light, I thought the acid/bi carb diet was a bit much #saving$$
As far as the chlorine, I'm just baffled. I'm for sure switching to liquid now. At my prior house, I had a 30,000 gal pool with a steady diet of the Leslie's tabs after reading the "off brand" issues. Never had a CYA issue. I do see the light, I thought the acid/bi carb diet was a bit much #saving$$
- May 3, 2014
- 58,276
- Pool Size
- 6000
- Surface
- Fiberglass
- Chlorine
- Salt Water Generator
- SWG Type
- Pentair Intellichlor IC-40
I have a variable speed pump, if that's what you're asking? Or auto jandy valves? Also, yes
- May 3, 2014
- 58,276
- Pool Size
- 6000
- Surface
- Fiberglass
- Chlorine
- Salt Water Generator
- SWG Type
- Pentair Intellichlor IC-40
If you have actuated valves, you have some form of automation. Most have a means to set up spillover to limit the run time of the spa spillover to reduce aeration.
- Feb 6, 2015
- 6,031
- Pool Size
- 12300
- Surface
- Plaster
- Chlorine
- Salt Water Generator
- SWG Type
- CircuPool RJ-45 Plus
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