Low chlorine

[purptiger]

Hi, I am a lurker and have hardly any chlorine in my pool. I have a SWG that seems to be running ok. I cleaned the element on 3/27/11. The element is only about 2 years old. The panel seems to register that there is enough salt in the pool to run. Here are my latest readings:

FC .02
PH 7.6
TA 90
CH 300
CYA 80
Borax 50
Salt 3500

The temp is 80. Is there anything that I am missing? purptiger

 

[dmanb2b]

Hey Purp

Try performing an overnight FC loss test to rule out organics. You may need to shock the pool

 

[zea3]

What temperature is the water? What percentage of chlorine production is the SWG trying to create? Did you double check the salt level with an independent test?

 

[purptiger]

First I do not know what a free chlorine loss test is. The temp is 80 and I am trying to get 1 ppm. By the way the swg panel is set at 80%. I use salt test strip.

 

[JasonLion]

The overnight FC loss test is described in Pool School here.

You should not expect the SWG to bring the FC level up from zero on it's own. They are designed to maintain the FC level when it is already at the correct level and everything else is properly balanced.

 

[dmanb2b]

First I do not know what a free chlorine loss test is. The temp is 80 and I am trying to get 1 ppm. By the way the swg panel is set at 80%. I use salt test strip.

Just to add that an FC of 1ppm is way too low for CYA at 80ppm per the FC/CYA chart in Pool school. This is why I was guessing you have something eating up your chlorine. As Jason linked, the OFCLT will confirm this for you. Have you read through Pool School?

Especially

pool-school/water_balance_saltwater_generator

pool-school/recommended_levels

 

[purptiger]

I had to wind up draining the pool to patch the Diamond-Brite. I replaced with city water. I called the people at Resillence and they told me to have the phosphates checked at a local pool store. What do you guys think? Thanks, purptiger

 

[JasonLion]

The phosphate level doesn't matter, just ignore it. Phosphates are one of the things algae eats as it grows. If you get rid of all the phosphates then algae has a much harder time growing, and so is easier to kill. But if you keep your pool properly sanitized, algae never gets started in the first place, and phosphates can be anything without causing any problems.

 

[purptiger]

I put 2, 1 lb bags of Leslies power plus to shock the pool on am 4/13/11. When I got home from work, I tested the FC and it read 5.0 and ph 7.6. Today 4/14/11 I tested it again pm and it read 3.5. I am trying to get the pool balanced with the chlorine, but do not know where to start. One poster said leave the phosphates alone, but the SWG manufacturer said to get the phosphates tested. If the CYA is 80 are you suggesting that I drain some of the water and lower the CYA? The PH is 7.6 and the TA was 90. The SWG manufacturer indicated that the system is doing fine, but that there is something eating the chlorine that the SWG is producing. He also said that city water tends to be high in phosphates to help keep the scale down in the pipes. I called Pinch-A-Penny and they told me the same thing about the phosphates (I should get them tested). Also, I had the CYA at 80 based on the SWG chemistry guidelines and the chlorine was the proper amount for 80 at the time.

 

[dmanb2b]

Purptiger, have you read pool school? Especially pool-school/shocking_your_pool

Shocking is a process and not a product. You'll have to decide whether you listen to the pool store or us. You have not shocked your pool at all. Adding 2 bags of powder is simply bringing your FC up a bit but not enough to be at shock level. Your shock FC target at CYA of 80 is 30ppm. Since your CH and CYA are in range for a SWG, you really should shock with only Liquid chlorine.

You'll also need a good test kit to take control of your pool and avoid being sold chemicals that may not fix the issue.