Trouble getting chlorine levels high enough...

[Prof100]

I joined this site in 2012, before my pool was installed. I have always used the TF100 and info from this site, and not the pool store. Everything with our pool has been great and no real problems or maintenance issues until 2 years ago. About halfway through summer, our FC levels started steadily dropping. I usually keep a CYA of 50-60 and FC at 7. Pool would get cloudy and dirty and we would add bleach to get things back in shape again. I bumped up the SWG percent to 95, but could only maintain about 3 FC. I figured the salt cell was shot, so I bought a new aftermarket cell and it didn't help. I tried a new Hayward cell, and it was about 1 number lower than the aftermarket cell. I also noticed the filter wasn't working properly and never really showed any dirt when backwashing. I finished out the year without doing anything else.

At pool opening last year, I replaced about 70% of the water and changed the sand in the filter for the first time. I added a variable speed pump and started running the filter 23 hours a day. I noticed that the pool was cleaner and the filter was needing backwashed a lot more, showing it was working. I brought my CYA up to 50-55, where I found was the sweet spot, but I was still having problems keeping the FC up. About 3 was as high as I could get it, when I would prefer to have around 7. We quit using the pool after July, so we didn't do anything else to it.

This year, I have the pool clean and in the process of bring the CYA up from 0. Test #'s are: FC-2.0, CC-.5 or less, PH-7.5, CYA is currently 0, TA is 150. Water is crystal clear. SWG is at 95%, where it's been for 2 years. I just checked it for phosphates, and it showed none. Does anyone have any idea why I can't get my FC up? Is my Hayward Aqua Plus control weak/shot and need replacing possibly, even though it shows it's working? Thanks for your help!

 

[tim5055]

The inability to keep the FC up and "Pool would get cloudy and dirty" along with constant filter problems tells me you have an ongoing algae growth in the pool.

Don't take the CYA above 30 until you complete an overnight chlorine loss test to see what is happening in the water.

Perform the Overnight FC Loss Test (OCLT)

The Overnight Chlorine Loss Test tells if the SLAM is finished or if you need to start a SLAM. This article says how to do the OCLT.

www.troublefreepool.com

My guess is you will fail. You will then need to SLAM the pool.

 

[JohnT]

What’s the reason you are running CYA so low? Hayward recommends 60-80ppm. I’d thing you’d have better performance at 70ppm.

 

[Prof100]

I tried 60, 70, & 80 years ago and it wasn't worth it. It did not ease the load on the SWG, so I found 50-60 was a good place.

 

[YippeeSkippy]

What size SWG do you have? Why aren't you supplementing the FC with liquid chlorine when your testing shows the FC too low??

Maddie

 

[Dave31410]

You show your pool as 38K gallons. The T-15 cell is rated at up to 40K so is probably undersized for your pool especially considering your geographic area.

 

[Prof100]

Ok, so I did the oclt. Fc was 2.0 at 5pm, I checked it again at 9pm @1.0, and just now at 1.5, so I would say there isn't an algae problem. As for why am I not supplementing, I will, but I shouldn't have to. When the pool was new, a swg setting of 95% would put the fc at 8.5-9.0 @90 degrees. Now it's at 95% at 73 degrees, and only 1.5-2.0. That's why I wonder if the swg system is weak. I'm not sure the pool is 33k or 38k gallons.

 

[ajw22]

Ok, so I did the oclt. Fc was 2.0 at 5pm, I checked it again at 9pm @1.0, and just now at 1.5,

Was your SWG OFF for the Overnight Chlorine Loss Test? It should be.

 

[Prof100]

Was your SWG OFF for the Overnight Chlorine Loss Test? It should be.

Yes. I flipped the breaker off to make sure it didn't come before I checked it.

 

[ajw22]

So how did FC increase from 1.0 to 1.5. Your test results don’t make sense.

 

[Prof100]

So how did FC increase from 1.0 to 1.5. Your test results don’t make sense.

Probably just margin of error and/or checking last night in the dark with a flashlight vs this morning with some daylight. I know I didn't lose more than 1.0 fc, so I passed the test.

 

[ping]

Raise the FC above 5ppm for the OCLT, turn off the SWG and run the pump overnight. Measure the FC and check for CC's when it gets dark and then early in the morning.

This is a classic case of the SWG making just enough chlorine to prevent a green monster from blooming but not nearly enough chlorine to kill all the algae.

 

[Prof100]

Raise the FC above 5ppm for the OCLT, turn off the SWG and run the pump overnight. Measure the FC and check for CC's when it gets dark and then early in the morning.

This is a classic case of the SWG making just enough chlorine to prevent a green monster from blooming but not nearly enough chlorine to kill all the algae.

I'll put some bleach in this am and get it up to 5-6 and test again tonight. I think the swg just isn't producing like it used to and needs replaced and/or a 2nd system installed.

 

[ajw22]

Probably just margin of error and/or checking last night in the dark with a flashlight vs this morning with some daylight. I know I didn't lose more than 1.0 fc, so I passed the test.

Redo Overnight Chlorine Loss Test following the instructions...

test your water for FC using the FAS-DPD test making sure your FC level is at least above 3ppm.

5 ppm is better to get a good test.

 

[Prof100]

Ok, finally done another test last night. Checked it a 9pm last night and this morning at 8:30. Sun was already starting to shine on the pool, but it only dropped .5, so there isn't anything in the pool consuming the chlorine. So back to my original thought that the SWG isn't producing like it should. It worked fine the first 5 years, as I could adjust the FC level anywhere I wanted, up to about 8-9. Now I can only manage 2-3. I may replace the circuit board on the aqua plus or just another SWG system and have 2.