I drained approx 2/3 of my water and my CYA is still high...@ 110!

[Jay15]

Hello,

I've been busy all weekend exchanging my pool water. I posted to my original thread last night here: My #'s Are Out of Whack and I Need Advice! but since I didn't get any responses there, I have to post here, but with an update.

I continued with the water exchange overnight and estimate that I replaced 2/3 of the water.

The current water level is at the bottom of the tile, so I have to fill about 3 more inches.

Here are my current numbers:
FC: 2.5
pH: 7.5
TA: 100
CH: 475
CYA: 110...

Feeling totally demoralized.

Question...Should I run the pool now to get the spa water (which I replaced completely) mixed into the pool water? (I'm assuming that should help, but with this CYA, I doubt it will help too much.)

Am I looking at continued draining? What would you do?

Please help...thank you.

 

[zea3]

Hi, did you run the pump before pulling a sample to test? What are you using to test the water?

 

[jb]

What methodology did you use to determine when you reached 2/3 drained? Could you have made an error?

 

[Jay15]

Hi, no, I did not run the pump, and I'm using the TF-100 test kit (just purchased 2 weeks ago).

 

[zea3]

Run the pump when the water is high enough and let it circulate about 15-30 minutes then pull another sample to test. You want to make sure everything is well mixed before testing.

 

[Jay15]

What methodology did you use to determine when you reached 2/3 drained? Could you have made an error?

I kept track of how long I ran the pump, how long I ran the fill hose, and I measured how many gallons per minute each one drained/filled. They were almost the same - the fill hose was 20 seconds slower than the drain hose. So based on the hours and gallons per hour, I'm estimating I drained 11,400 gallons from the 18k gallon pool.

 

[Jay15]

Run the pump when the water is high enough and let it circulate about 15-30 minutes then pull another sample to test. You want to make sure everything is well mixed before testing.

Makes sense, thank you! I'll report back in a little while.

 

[Jay15]

Ok, I'm back. I ran the pool pump for an hour+

Here are the new numbers as of 4:30 pm (Air temp 95/water temp 88)

FC = 1.0
pH = 7.5
TA = 100
CH = 450
CYA = 100 - 110 (probably 110) (I did it 3 times)
CSI = .07

Would any amount of draining get this CYA in check? I'm so bummed out.

What can I do?

(Also, I'm thinking that my pool volume might be higher than the estimated 18,000 from the plans because I remember the builder saying it was about 20k gallons. The dimensions are 35' L x 22' W, Area=539, Perimeter 98', Depth 4x5x6 (with a 6" deep 7' tanning ledge + 3 steps). When I put these #'s in pool math, it came out to about 24k but that would be without the tanning ledge). Anyway, I changed my signature to 18-20k gallons.)

 

[jb]

Edited to notice you did use an exchange process.
I think you need to keep exchanging or just wait for a rainy day and go for it, that's what I did, I exposed many feet of plaster. Another thing to consider is our season is coming to an end. While we swim after September 15, statistically in our house (geographically not far from you) not many do in the last 20 years so you need to decide what to do to enjoy your pool the next 45 days.

 

[Jay15]

Thanks. It just seems like there's no amount of draining I could do to get rid of the CYA...

What is the harm in keeping the CYA this high? Just having to use more chlorine? (btw I'm switching to liquid chlorine and never using the tablets again.)

 

[Jeff J.]

Thanks. It just seems like there's no amount of draining I could do to get rid of the CYA...

What is the harm in keeping the CYA this high? Just having to use more chlorine? (btw I'm switching to liquid chlorine and never using the tablets again.)

Just so you know, 100 is the limit of the CYA test. If you are getting 100, you should test a 50/50 tap water / pool water sample. Also, the CYA test is notoriously tricky. You have to shake the bottle for thirty seconds, wait thirty seconds, shake again for thirty seconds, have your back to the sun, hold the viewing tube at waist level, and just glance, don't stare, at it.

 

[Jay15]

I took a sample to Leslie's today and here are the results. They said to add 40 oz muriatic acid, wait 4 hrs, then shock the pool 3#.

Interestingly, the sample I took to Pool Stop last week, before any draining, showed my CYA at 150 which they deemed "good" because their range is 30-200. WTH?

 

[Jay15]

Edited to notice you did use an exchange process.
I think you need to keep exchanging or just wait for a rainy day and go for it, that's what I did, I exposed many feet of plaster. Another thing to consider is our season is coming to an end. While we swim after September 15, statistically in our house (geographically not far from you) not many do in the last 20 years so you need to decide what to do to enjoy your pool the next 45 days.

I guess I'll try to keep exchanging some water over the next few months and take advantage of any rain, and also not using chlorine tabs any longer.

But I'm still REALLY confused as to why the CYA barely budged after replacing so much water.

Will it ever get lower??

Also, we do swim into September, plus we use our spa a lot in the winter.

 

[zea3]

100 is the upper limit of the CYA test. It was probably much higher than you thought. If you look at the test cylinder, the markings become closer together the higher the CYA level is. It is difficult to get an accurate reading over 100ppm because the tube cannot be graduated that precisely as the lines would be extremely close together. Test a 50/50 mix of pool water and tap water and use that to test the CYA level and double the result to get a ballpark test result. That will let you know how much you will need to drain.

You can run the pool with 100ppm of CYA, just use liquid chlorine and keep the target FC in ratio with the CYA level. Try and stay on the high end of your FC as a pool with high CYA can get out of control quickly.

 

[mguzzy]

I concur with @zea3 , I bet your CYA level was higher than you thought if you didn't do a diluted test to begin with. I couldn't find where you did that in the first thread either, unless I missed something. OR-The other thing I noticed in your other post is I couldn't see where you checked the temperature at the bottom and the top of your pool when you are doing your drain. for this technique to work the fill water has to be warmer than the pool water for it to "float" above your drain water. .. if that makes sense. If the fill water is colder and you are pumping from the bottom, you just pumped out your fill water instead. The idea is to take advantage of the thermocline created between the waters of different temps and pump out the water layer that you are not filling with. just thinking out loud here.

 

[Jay15]

I concur with @zea3 , I bet your CYA level was higher than you thought if you didn't do a diluted test to begin with. I couldn't find where you did that in the first thread either, unless I missed something. OR-The other thing I noticed in your other post is I couldn't see where you checked the temperature at the bottom and the top of your pool when you are doing your drain. for this technique to work the fill water has to be warmer than the pool water for it to "float" above your drain water. .. if that makes sense. If the fill water is colder and you are pumping from the bottom, you just pumped out your fill water instead. The idea is to take advantage of the thermocline created between the waters of different temps and pump out the water layer that you are not filling with. just thinking out loud here.

MGuzzy - I followed these directions from TFP. The temp difference was only about 5 degrees (tap water here in TX is not very cold in the summer) and my CH was very high, so I pumped from the deep end/filled into the shallow end skimmer. I doubt that the fill water was colder than the deep end water. But I could obviously be wrong...Thank you for checking my posts!

"Pump from the deep end or near the surface?
To determine whether you pump from the deep end of the pool or from near the surface of the pool, depends on your fill and pool water characteristic.

Adding water to the deep end while pumping from a top step or near the surface is recommended if your fill water is much colder (>20F) then the pool water.

Put the pump in the deep end and fill from the shallow end if your fill water is nearly the same temperature as the pool water, you have a saltwater pool, or have very high CH. Put the fill hose in the skimmer, if you have one, in the shallow end. If no skimmer, then use a bucket to put the water hose in and have the top of the bucket above the pool water surface. Be sure to secure the hose to the bucket."

 

[Jeff J.]

MGuzzy - I followed these directions from TFP. The temp difference was only about 5 degrees (tap water here in TX is not very cold in the summer) and my CH was very high, so I pumped from the deep end/filled into the shallow end skimmer. I doubt that the fill water was colder than the deep end water. But I could obviously be wrong...Thank you for checking my posts!

"Pump from the deep end or near the surface?
To determine whether you pump from the deep end of the pool or from near the surface of the pool, depends on your fill and pool water characteristic.

Adding water to the deep end while pumping from a top step or near the surface is recommended if your fill water is much colder (>20F) then the pool water.

Put the pump in the deep end and fill from the shallow end if your fill water is nearly the same temperature as the pool water, you have a saltwater pool, or have very high CH. Put the fill hose in the skimmer, if you have one, in the shallow end. If no skimmer, then use a bucket to put the water hose in and have the top of the bucket above the pool water surface. Be sure to secure the hose to the bucket."

You've got to find out what your actual CYA is. Do the diluted test. And don't rely on the pool store results.

 

[Rancho Cost-a-Lotta]

You can run the pool with 100ppm of CYA, just use liquid chlorine and keep the target FC in ratio with the CYA level. Try and stay on the high end of your FC as a pool with high CYA can get out of control quickly.

One thing to keep in mind is pH test results become invalid with chlorine levels above 10 ppm. If you confirm your CYA is 100 ppm, your daily target for FC is 11 to 13 ppm. The minimum is 8 ppm. If you test your pH before your add your daily dose of chlorine, you'll get a more accurate reading.

You won't use more chlorine on a daily basis; in fact, you're daily loss will likely be less with a higher CYA level. You'll use a bit more chlorine once during the initial bump to your target level.

Best of luck!

 

[DorsalSpine]

Were you running the pump during the water exchange? The objective is to get the water to separate in distinct layers. You need to do the diluted water test with your CYA. My first reading was 100+, diluted it was still 100+. With a CYA of over 200 I had to change a lot of water.

 

[Jay15]

Were you running the pump during the water exchange? The objective is to get the water to separate in distinct layers. You need to do the diluted water test with your CYA. My first reading was 100+, diluted it was still 100+. With a CYA of over 200 I had to change a lot of water.

No I did not run the pump until after the water exchange.