Can't maintain chlorine levels
- Thread starter joelalbert
- Start date
- Jan 4, 2016
- 5,288
- Pool Size
- 44000
- Surface
- Plaster
- Chlorine
- Salt Water Generator
The test strips are unreliable, so just post the K-2006 numbers.
So, your CYA is too high, so that's the first thing we need to deal with. When the CYA is too high, it ties up too much of the chlorine and leads to problems like you're experiencing. This means that some of the pool water will need to be drained out and then the pool refilled. So we need to find out how much too high. The test only goes up to 100, so it could be much higher.
Carefully measure 2 cups of pool water, and pour that in a bowl. Using the same measuring cup, measure 2 cups of tap water and add that to the bowl. Do it again, so that there's 2 cups of pool water and 4 cups of tap water, well mixed. Take your 7 mls for the CYA sample from the mixture. Do the test and then let us know. Your result for the pool water will be 3 times what you see in the test. So if it's 50, the pool water is at 150. Then we can plan the drain/refill and SLAM properly.
So, your CYA is too high, so that's the first thing we need to deal with. When the CYA is too high, it ties up too much of the chlorine and leads to problems like you're experiencing. This means that some of the pool water will need to be drained out and then the pool refilled. So we need to find out how much too high. The test only goes up to 100, so it could be much higher.
Carefully measure 2 cups of pool water, and pour that in a bowl. Using the same measuring cup, measure 2 cups of tap water and add that to the bowl. Do it again, so that there's 2 cups of pool water and 4 cups of tap water, well mixed. Take your 7 mls for the CYA sample from the mixture. Do the test and then let us know. Your result for the pool water will be 3 times what you see in the test. So if it's 50, the pool water is at 150. Then we can plan the drain/refill and SLAM properly.
- Jan 4, 2016
- 5,288
- Pool Size
- 44000
- Surface
- Plaster
- Chlorine
- Salt Water Generator
The CYA at that level is almost completely eliminating the effectiveness of chlorine as a sanitizer, so you'll need to drain and refill. Have you been reading about that? Let me know any concerns you have. The upside is that you'll be able to keep the pool healthy. You'll need to be concerned about your local water table so the pool doesn't lift from hydraulic pressure in the ground. You will purchase or pump the least amount of water by doing it all at once, or you can do multiple drain/refills and you will replace more water. Both methods get you to the same place. Sorry to hear about your high CYA number 
How do I drain gradually and after doing so what is the best kind of chlorine to use to avoid this problem again?
To avoid CYA buildup, the best chlorine is liquid bleach or liquid chlorine (they're really the same thing). Liquid builds up salt over time. Calcium Hypochlorite builds up Calcium (adds to your CH number). DiChlor and TriChlor add CYA.
No matter what you add, something will build up since chlorine needs to be bound to something to not be a gas. Most of us prefer to build up salt (which can be just fine nearing 1000, 2000, or even 3000ppm) instead of calcium or stabilizer (CyA) (which get to be a problem at far lower concentrations).
No matter what you add, something will build up since chlorine needs to be bound to something to not be a gas. Most of us prefer to build up salt (which can be just fine nearing 1000, 2000, or even 3000ppm) instead of calcium or stabilizer (CyA) (which get to be a problem at far lower concentrations).
- Jan 4, 2016
- 5,288
- Pool Size
- 44000
- Surface
- Plaster
- Chlorine
- Salt Water Generator
Re: drain/refill, lowering CYA from 270 to 55 PPM CYA:
You can drain/refill 80% of the water
You can drain/refill 55% of the water twice (110% of water needed for refilling)
You can drain/refill 41% of the water three times (125% of water needed for refilling)
This is just math - reality is that it's hard to tell this exactly because of pool shape, but hopefully this perspective is helpful.
There are other methods, such as the tarp method, although I've also heard it doesn't work. I know the key is to draw water from under the tarp, so the tarp must be kept away from the skimmers and drains. It's described here:
New User - Doing first drain - What do I need to know?
And link to the tarp removal video which gives you the overall concept
Dropbox - Video May 08, 7 20 37 PM.mov
This member is doing "fill at bottom" "drain from top"
Neighbor's CYA off the charts - where to start?
And here's some more discussion
CYA 100. Can I drain from top and fill from the bottom?
If there's no risk of the pool lifting, least hassle is drain 80% and refill. Hopefully an expert can discuss pool lifting risk with you. I've only heard of it and don't know anything helpful on that topic.
You can drain/refill 80% of the water
You can drain/refill 55% of the water twice (110% of water needed for refilling)
You can drain/refill 41% of the water three times (125% of water needed for refilling)
This is just math - reality is that it's hard to tell this exactly because of pool shape, but hopefully this perspective is helpful.
There are other methods, such as the tarp method, although I've also heard it doesn't work. I know the key is to draw water from under the tarp, so the tarp must be kept away from the skimmers and drains. It's described here:
New User - Doing first drain - What do I need to know?
And link to the tarp removal video which gives you the overall concept
Dropbox - Video May 08, 7 20 37 PM.mov
This member is doing "fill at bottom" "drain from top"
Neighbor's CYA off the charts - where to start?
And here's some more discussion
CYA 100. Can I drain from top and fill from the bottom?
If there's no risk of the pool lifting, least hassle is drain 80% and refill. Hopefully an expert can discuss pool lifting risk with you. I've only heard of it and don't know anything helpful on that topic.