Calculating CH rise in Phoenix

[sikovital]

Wrote you all last fall about my new pool, rising CH, plaster-quartz composite interior. Finally, the end of October, the CH leveled off at 850. I have a kit that's been tested against standards, and I have been consistently getting a reading of 825-850 since the end of October.

Fill water, Central Phoenix, was 170 ppm when tested in June and September. Now, it's gone up to 325-350, my reading and Leslie's. Found out from City that a couple of the plants are being serviced, the canals are being cleaned, so we're getting our water from a different source, which explains the higher CH coming from the tap. Even when the plants are back on line, the CH levels in the tap water will be up and down for awhile. We were going to drain and fill this weekend, since the temps will be in high '60's and cloudy, so no freeze at night. But if we're starting out with water with a CH of 350, won't we be back up to 650-700 or so by the end of the summer? And with the whacky weather we've been having, I hate to wait. This could be the last perfect weekend for draining.

Pool is about 13600-13750 gal. Large Pentair sand filter. VS pentair pump, auto water level. Barracuda for nightly cleaning at rate fast enough to turn over water in pool. During the day, run on 1800 rpm with UV. We use chlorine tabs in summer, and in fall switch over to liquid chlorine.

I know from our previous discussions, and by now, experience, that you can manage a pool with high CH, but it's a giant pain, and I'd like to reduce the amount of time I have to spend worrying about the CSI and LSI levels.

Also, have to clarify that the "expert" did tell me that if one of the other readings is high or low, you can compensate with the others. I've been watching both the CSI and LSI levels. Ph still rises .l almost every night, but it's much easier to keep things in line when the water is cold, but Man, it isn't any fun sticking your arm in that water-- even if it is only twice a week.

Has anyone had any luck with the new product that reduces calcium levels--Caltreat? Maybe that will be an option after next summer.

Thanks, guys.

 

[linen]

Also, have to clarify that the "expert" did tell me that if one of the other readings is high or low, you can compensate with the others. I've been watching both the CSI and LSI levels. Ph still rises .l almost every night, but it's much easier to keep things in line when the water is cold, but Man, it isn't any fun sticking your arm in that water-- even if it is only twice a week.

I assume you have read?: http://www.troublefreepool.com/pool-school/calcium_scaling You can deal with high CH by keeping the ph lower and also by maintaining a lower TA. What is your current TA level? Also slowing down evaporation will help...do you use a cover when the pool is not in use?

Has anyone had any luck with the new product that reduces calcium levels--Caltreat?

We have not heard much about this product, but what we have heard has not been conclusive as to its effectiveness. Here is one of a few posts on here discussing it: http://www.troublefreepool.com/trying-caltreat-t43236.html

 

[Richard320]

Never heard of Caltreat, but I have heard of Calsaway Get rid of CH and CYA buildup at the same time!

 

[sikovital]

Re: Calculating CH rise and Pool Draining in Phoenix

Appreciate the input, but I really don't want to deal with the high CH and covering our pool in the heat of the summer. Won't that just make the water hotter? We're swimming in 90 degree water during the summer as it is. And we have storage issues, like the look of the pool--it's part of the landscaping. We're outside a lot.
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So, I'm trying to figure out if I fill the pool with water that's 300 ppm CH, will it be up to 600 or so by the end of the summer if the fill water stays at 300. Or what will it be if we fill the pool this weekend with 300 ch water and the fill water used to replace the evaporated water in the summer goes back down to 170. Anyone have a formula?

The reason I'm asking these questions is because I'm trying to decide whether to drain the pool this weekend while it is cloudy and rainy, no chance of freeze. Our pump needs to be on when there's a chance of freeze to protect the UV unit. CH coming out of hose bib is 300 right now due to City water plant closures and canal draining for maintenance, so our water is coming from a different source. The water we get from the City is usually 170--we're in Central Phoenix. Anyway, I'd like to wait until the water is 170 again, but the weather is perfect for a draining, and I'm afraid we'll have whacky up & down weather that will be cold with potential for freezing at night and then too hot.

As I said, I'd like to wait until the CH coming from the City is back down to its normal 170 or so to drain and refill. Finding sparse information on how sensitive pool interior actually is to the sun depending on how full the pool is. Have a quart composite, similar to Ultrapoz, 13600 gal. If we drain the pool on a day in the 70's late afternoon, it'll take about 4 hours, and then fill time is about 23 hours. So, by 7 or 8 a.m., the pool will be half full. I'm assuming that even if it's a sunny day in the 70's that because the pool is half full, it won't be detrimental to the pool surface? No one would ever be able to drain their pool in Phoenix. I'm also getting conflicting info about temperatures for pool draining. One source said less than 90 degrees, and one said less than 80 degrees.

And just some interesting information: Talked to a guy from the City who said that when we drain our pool, we're not wasting water. Yes, we have to pay for it, but the water is treated by a plant in Southwest Phoenix and then flushed into a nature preserve wetland. Nice to know.

Thanks again.

 

[chem geek]

As noted in the thread Water Absorption and Heating from Sunlight, around 60% of the sun's energy is absorbed in a white plaster pool of usual depth. If you put on a white or reflective opaque pool cover, you will eliminate this absorption of heat and also eliminate the evaporation that is increasing CH via the fill water. There will be minimal heat gain and you can actually cool the pool if you remove the cover at night due to evaporation.

 

[sikovital]

Great idea. Thank you.