Could this be Right?

[mkfmedic]

Hello Again,

As the summer transitions to fall and the weather cools, I have gone about 10days between tests. There has been no swimming load in that time and the weather here at the coast (Huntington Beach, CA) has been in the high 60's to low 70's.

As a reminder, our pool is in the neighborhood of 10,000 gallons is sanitized utilizing a Jandy SWCG and DelOzone II. I have been running our pool for approximately 6 hours a day, but have considered reducing that time for the season change? Up until today, the results have been fairly consistent.

Water Temp 68F

FC - 8
CC - 0
TC - 8

pH - 8.2 +
Alk - 90
Cal - 350 - 400 (Again, I had a hard time with this test and repeated. While adding drops to change water back to blue, it seems that I get the water to a relatively "clear" state at around 330, and a very lite blue between 350 and 400. There did not seem to be a significant change of color after 350. Even though the light blue is very lite in color. Would this indicate a Cal level of 350?)

My CYA level is 70.

Now, after my previous testing at the beginning of the month, I felt my chlorine was a little high. It was registering on the daily test at 5+, so I turned my SWCG down to 25%. I do have the largest Jandy SWCG model in combination with the Ozone system. I expected to find my chlorine on the low side today and was shocked to find it at 8. I repeated the test and found that it remained at 8. In my novice opinion, these results indicate that first I need to ADD acid, and second, turn down my SWCG (15% perhaps) and retest after a couple of days.

Any thoughts? My pool remains clear and clean and we have a navigator running around the bottom. No algae or any other issues. Could the high chlorine be the simple result of lower temps and no swimming load?

Thanks again for everyone's input and support. I am looking forward to your responses.

Regards,

Mike

[chem geek]

Yes, the lower temperatures mean algae growth is low or non-existent. Not having bather load means you aren't adding ammonia compounds nor organics into the pool (except for what blows in). And this time of year the sun is lower in the sky and not as strong (about 60%, depending on latitude; cloudy days have much less UV) so less chlorine gets broken down by sunlight. Put all this together, and the chlorine usage goes way, way down. If you add a cover to your pool, the chlorine may only drop 0.5 to 1.0 ppm in a week (if you shut off your SWCG) so lowering your SWCG way down is appropriate.

And yes, you need to add acid if your pH is truly correct.

Richard