Chlorine not budging

[denanbob]

I have an odd "problem" (??? not sure if I can call it that). After I cleared up my medium green water at opening (rather easily I may add), I was focused on lowering the ALK and raising the PH. Once that was in balance (good enough....150 alk and 7.4 PH), I chlorinated up to 4-5ppm, swept and ran the filter/fountain for a few days. Then, I shut off filter and covered with solar cover to try and warm the 60 degree water up. Almost 3 days went by (of non-stop baseball games) and I realized I neglected my pool. No filtering or chlorine for 3 days. I tested this morning and chlorine still 5ppm. How is it that it didn't budge?? Lack of sunshine? 60 degree water? I guess I'm not complaining, but I'm confused. My CYA is around 60 according the the pool store. Here are all my numbers:

TC - 5ppm
PH - 7.4
ALK - 150
TH - 450
CYA - 60
water temp - 62

15x30 AG 10,500 gallons, vinyl liner

Is chlorine at 5ppm too high to swim in if the temp warms up? Based on a CYA of 60, shouldn't my chlorine always stay around 5ppm?

Thanks everyone! I'm learning!

Dena

[chem geek]

With a pool cover that keeps out UV rays, the chlorine won't breakdown from sunlight. In cooler water temperatures of 60F, there won't be much algae growth and all chemical reactions are slowed down significantly including chlorine's oxidation of organics. So it is not unusual to measure no chlorine loss over a few days. When my pool is closed with an opaque cover and when the water temp is 55F or lower, the chlorine usage is less than 0.4 ppm FC per week so probably isn't even measurable over a few days.

Now that my pool is up to 85-88F, even with the opaque cover I see chlorine usage of around 0.5 - 0.7 ppm FC per day (at around 3 ppm FC with 20-30 ppm CYA) and that's likely to be prevention of algae and oxidation of organics that get into the pool since we do use it a few times a week (and obviously have it uncovered for a few hours when we use it so sunlight breakdown is also a part of the chlorine loss).

Your chlorine level is fine for when the pool warms up. 5 ppm FC at 60 ppm CYA is a good level to maintain as a minimum so it might need to be higher (perhaps 7 ppm FC) at times during heavier use so you end up with 5 ppm FC the next time you add chlorine.

Richard

[iwannapool]

Solar covers triumph again! Covering your pool kept the sun from burning off and allowing your CL to dissipate into thin air, and of course your CYA helped a bit.

[denanbob]

Thank-you! Makes sense.........now if I could just get that water to warm up so we could USE the pool with the perfect water in it! LOL!

[Watermom]

Have you thought about buying a solar heater? They make a big difference in the temp of a pool - especially if you use a solar cover at night to keep from losing heat. Your post doesn't say where you live. I live in Charleston, WV and by using the solar heater and solar cover, we have been swimming since the beginning of May. In the middle of the month, we got a few cold nights and lost a little heat, but quickly rebounded. My water temp today was 84. Just about perfect!