Chlorine Demand

[aylad]

I would not use either dichlor or cal-hypo, because your calcium and CYA are both already high. I would use plain, unscented bleach. In 23K gallons, each 3 quarts of 6% bleach will raise your FC by roughtly 2 ppm. With a CYA of 70, you need to raise your chlorine to shock level, which for a CYA of 70, would be 20 ppm. To get from 0 to 20, that means 7.7 gallons (8 to be on the safe side). You need to test the water as many times a day as possible, and add whatever amount of bleach is needed to get back up to the 20 ppm. Hold it there (the more consistent you are, the faster you'll get there) until you can measure chlorine at night and again the next morning before the sun is on the pool, and not lose more than 1 ppm of chlorine in that time. Then you can let it drift back down, but never below 5 ppm.

I suspect you have algae trying to bloom, and you have been chlorinating enough to keep it at a standstill, but not enough to kill off what you can't see. If you'll shock as described above, it should correct the problem.

I wouldn't use any more stabilized chlorine--no dichlor powder or trichlor tabs. I would switch to plain bleach for your chlorination to keep those CYA levels from getting any higher.

Janet

[Watermom]

To add to the advice that Janet gave you above, your pH is a little low. Use some 20 Mule Team Borax (laundry aisle at Walmart) to bump it up a little. Aim for 7.4-7.6 but anywhere 7.2-7.8 is ok. Start by adding a half a box slowly to the skimmer while the pump is running. Retest after a couple of hours. NOTE --- You cannot get an accurate pH reading when your chlorine level is high. Adjust your pH a little first because with a chlorine level of 20, you won't be able to get a true pH reading.

[gfritz1]

Can I use Lithium shock as have a pile of it?

[PoolDoc]

I don't think it will hurt anything to use it, and it will add chlorine, so yes, go ahead.

[gfritz1]

Janet - will return from work in kY on Friday and will address the pool.Part of my issues is have been working in KY away from home and treating the pool remotely . I am debating about doing a partial drain on my return to get the cya down a little realizing that it is costly . Whats the advantage of doing this or not doing it? I think the cya is probally higher since these readings as have been eating tri clor tabs at a rapid rate

I am looking at using lithium shock since have a supply but unsure enough to raise the leave to 20 ppm and maintain it. Where can I find a formual to calculate the amount needed to bring my pool to 20 at 23000 gals? If I understand correctly I need to start at night and keep feeding the chlorine to keep at 20ppm until the next morning? Sounds like I raise to 20ppm and keep measuring and adding as it drops to get above 20 for a 12 hr period? Then keep at 5 ppm
As for not using tabs you say use bleach .What amount and at what frequency ? Thanks as cant wait to get this behind me. One more questions A&H Baking soda compared to Borax or to PH+ what is the difference as I really need to get my PH up

[Watermom]

In your pool, each gallon (4 quarts) of plain, unscented 6% bleach will add about 2.5ppm of chlorine. Use that as a reference to help you figure out doses of bleach to add. Each time you test the chlorine, add enough bleach to get back up to shock level. You want to keep doing this until you can go from sundown one evening to within two hours of sunrise the next day without losing more than 1ppm of chlorine overnight. Then, keep the chlorine high for one more day for added insurance and then you can let the chlorine drift down and make sure to keep it between 5-10ppm ALL the time. (See the Best Guess Chlorine Chart in my signature up in post #2 for info on the relationship between CYA and chlorine levels.)

20 Mule Team Borax (laundry aisle at Walmart) is used to raise pH and baking soda is used to raise alk.

[gfritz1]

OK THANKS for the help -I did a partial drain upon returning as took down roughly 15inches and refilled starting Friday soi refill was Sunday and Sunday night and Monday added the 20 Mule Team . It took roughly 8 lbs (2 boxes) plus a 5 lb PH+ I had but it is now 7.8 and holding .AMAZING .Last night at dark with a FC of zero added 8.5 gals of bleach and 2- 15000 bags of shock . FC was above 20ppm and by daylight it was still above 20ppm.Extremely sunny day in PA so pool has been in sun all day .It sparkles. My present readings almost 24 hors after super shock FC 12.5PPM CC 0 TC 12.5 PH 7.8 Hardness 190 Alk 140 and cya 72. So FEEL PRETTY GOOD NOW . The chlorinator is off and empty . So what do I do now to continue ? I know you said no more tri chlor or the shocks others then lithium or bleach. What do I use to replace the chlorinator for daily treatment? I assume still add alegcide on weekend and the shock (bleach-how much?) .This is amazing -await your response - GFritz1

[Watermom]

Just use bleach for your daily chlorine. With a CYA of 72 (how did you get that number??), you need to keep your chlorine levels between 5-10 all the time. You do not need to use algaecide and you also do not need to routinely shock unless you are having a CC reading greater than 0.5, cloudy water or see the beginnings of algae. If you maintain your chemistry properly, you rarely need to shock.

[gfritz1]

CYA was measured with the Taylor Test Kit and looking until the Black Spot disappears. The Pool place got 50 using test strips .

Understand to use the bleach so this means daily check of chlorine level and then based on reading add bleach with each gallon expected to raise my ppm by 2.5

Is there a better time to add the bleach? I normally run pump from 7am-7pm and the swimmining usually is from 2-6 but normally only adults doing laps. I understand need to keep higher but like this weekend grandchildren will be here. Whats the safe limit for them to swim-upper ppm level -----thanks again

[Watermom]

The best time to add bleach is in the evening when the sun is off the pool. In that way, all the chlorine can go to oxidizing the goo in the water and none of it will be lost to the sun. However, it is also ok to add it at other times. Especially when a pool is fighting algae, or has a high chlorine demand for some reason, etc.

Keep your chlorine between 5-10ppm. Your grandchildren are perfectly safe when swimming with chlorine at those levels with a CYA of 70ish. (Actually, it is also fine to swim when chlorine is at shock level but you probably would want to wear an old swimsuit if you did so.) People are often afraid that a chlorine level of 5-10ppm is too harsh; but the fact is that with a CYA of 70, chlorine is no harsher at 5-10ppm than it is at 1-3ppm with no CYA.