Can't keep chlorine

[Christal]

Last year we installed used above ground pool that was given to us from my inlaws. It is 28' in diameter and 4' deep with a new liner and filled with well water if that matters. It came with a Hayward ProSeries model S108T filter and Hayward Power-Flo XL pump. All last season we could not keep chlorine in it and the PH and Alkalinity were high, however as long as it was vacuumed once a week the water stayed clear. Even when I put three gallon of liquid chlorine in at a time all or most of the chlorine would be gone in less than 24 hours. When we opened the pool up this year other than some very minor algae spots and a little dirt the pool looked ok but it had no chlorine. Almost a month later and at least 16 gallons of chlorine it still will not keep chlorine. Right now I have AquaChek test strips but as of about 20 mins. ago I have a real test kit on order from Amazon. Yesterday morning I put almost a whole container of PH down in the pool along with two gallons of chlorine. Five hours later there was almost no chlorine but the PH was down to the 7.8 range.
This morning when I tested the water this is what I got
PH 7.8
FC 0
TA 240
Stabilizer 30-50
Help please!

[Watermom]

Test strips are so unreliable that who knows what your readings actually are! When is your test kit due to be delivered? Can you go to Walmart and see if they have a 6-way drops-based kit or at the very least a cheap OTO/Phenol Red kit (red and yellow drops). Even though you have ordered the other kit (good decision!:)) you will still be able to use either one of these cheaper kits as well for quick daily testing. In addition to my Taylor K2006 kit, I use my little kit all the time!

Welcome to the Pool Forum!

[Christal]

The kit from Amazon will be here in 5-6 days after it ships. I will go to Walmart tomorrow to see what my options are there. I did have a pool store test the water and when they tested two weeks ago the numbers were similar with the chlorine at 0. I don't have the print out anymore so I can't give the true numbers.

[Watermom]

Ok. Post some numbers tomorrow and someone here will try and help.

[Christal]

Sorry for the delay it is the last week of school here so it had been kind of crazy. My test results with the six way test kit are:
PH 7.8
CL 0
TA 280
TH 360
CYA is lower than 30

So after the tests my guess is that I need to focus on raising the CYA since my test water was only slightly hazy and not cloudy at all.

[Watermom]

Yes, add CYA.

Do you use cal-hypo? Or is your fill water really hard? Just trying to figure out why your calcium hardness is so high.

Your TA is way too high. It should be more like 80-120. That, combined with high calcium hardness and high pH is not good. Read the following threads to help you learn how to lower your TA.

http://pool9.net/ma/
http://pool9.net/alk-step

(Until your registration is completed, you'll have to copy the link and then log out and paste it in a browser window to be able to see the page it points you to.)

[PoolDoc]

If you have a Sams Club nearby, try to get some of their dichlor. Dichlor adds about 9 ppm CYA for every 10 ppm of chlorine added:
http://pool9.net/sams-dichlor24/
http://pool9.net/sams-dichlor50/

Most other sources sell diluted or blended dichlor, but any dichlor showing 56% or more available chlorine is probably OK.

You can also buy plain stabilizer, but it's slow to dissolve, or liquid stabilizer, but it's much more expensive.

[Christal]

Yes, add CYA.

Do you use cal-hypo? Or is your fill water really hard? Just trying to figure out why your calcium hardness is so high.


We live in a rural area and have very hard well water. A water softener is pretty much required here unless you would like to buy a new water heater, dish washer, and washer every few years! So the calcium hardness level doesn't surprise me.

[Christal]

I will make a trip to Sam's this weekend to see if they have dichlor. Thanks!

[Watermom]

You are welcome! :) Keep us posted how things are going for you.

[Christal]

Just a quick update. We bought the dichlor and followed the directions for shocking the pool. We added two pounds on the first night, and the next morning the CL was 5 and there was a lot of junk at the bottom with a slight green haze. I vacuumed and it looked better but not great. By that evening it was back down to zero. We shocked the pool again with another 2lbs. of dichlor and again the next morning the CL was 5 with more junk to vacuum. That evening it was barely showing any chlorine. So that evening we shocked the pool again with 3 lbs. of dichlor. Yesterday morning for the first time ever the chlorine level was high and the test was dark yellow almost orange. The CYA test was blurry at 30 which is a huge leap from the crystal clear it was a few days ago. Yesterday evening the CL was 5 so our pool actually held chlorine for 24 hours and the PH is at 7.5! Today the pool looks great. When I need to add more chlorine I will continue to use the dichlor until the CYA level get somewhere between 30-40, then I plan to switch back to liquid chlorine.

Thanks for the help!

[PoolDoc]

You might want to let the CYA get higher than 40. That way, you can add larger doses, and have them last longer. That becomes especially important if you plan to go on vacation and leave for a few days.

The Cl-CYA chart explains what's going on: http://pool9.net/cl-cya/