numbers from test

[mrs.rainbow]

I redid the cya test and it is 40?/ I think , if Im reading it right. Thanks for your help Janet.
rainbow

[aylad]

That makes much, much more sense. Now...did you fill your pool from a well (checking to make sure there's no iron in the water) or from city water?

If you filled from a well, that's a whole 'nother ball game, so disregard what's below for now. If you didn't......

You need to shock the pool by bringing your chlorine level up to 15 ppm. In a 20K gallon pool, each 1.5 gallons of 6% bleach will raise your chlorine by 4.5 ppm. Each 1.5 quarts will raise your FC by just over 1 ppm. You're shocking in order to burn off that CC, which is an indication that the chlorine in your water is fighting something, probably algae. Once you're at 15 ppm, then you need to test and add more bleach as many times as possible during the day until you can test at night and again in the morning before the sun is on the pool, and not lose any chlorine. At that point, you can let the chlorine drift back down to the 3-6 ppm range, but never let it get below 3 ppm. Keep the pump running 24/7 during the process, backwashing your filter as needed.

BTW, need to fix the volume in your signature--I'm assuming it's 20,000 gallons and not 2000....

[mrs.rainbow]

Hi aylad,
I do fill from a well, so I,m assuming that makes a difference in readings? I added three gallons of bleach tonight and will test again tomorrow. The combined chlorine should be at zero, but how do I increase the FC w/out increasing the cc as well?
Thanks,
rainbow

[aylad]

Most folks that fill from a well have iron in the well water. When you add large doses of chlorine to water with iron in it, the iron can precipitate out and cause brownish or orangish staining of the water and/or liner. If you've added bleach to get up to 9 ppm with no browning of the water, you may be one of the lucky ones. If you do start to see browning of the water, then you'll need to add some metal sequestrant to keep the iron suspended in the water. Do you have brown or orange stains in your toilet tanks?

When you put chlorine in the pool, some of the chlorine combines with the "nasties" in the water to sanitize them. This is registered as CC. Once your CC gets to 1 or above, then by shocking the pool you're adding enough FC to overcome whatever the "nasties" are in the water, and you should see the CC go back down to zero, which is where you want it to stay.

Does that help?