Hello all. Recently dumped my pool service and their pucks and started using liquid chlorine only. My CYA is 60 which forces me to have my FC at 7. My question is, I live in a hot desert climate with high temps and low humidity which leads to a fair amount of evaporation. I can lose 1/2" to 3/4" of water on some really hot days. Over time, will my CYA level drop due to adding water to my pool every couple of days? I live in CA, so draining is not an option.
CYA reduction by water evaporation
- Thread starter gary300
- Start date
- Jun 22, 2014
- 47,796
- Pool Size
- 17888
- Surface
- Fiberglass
- Chlorine
- Salt Water Generator
- SWG Type
- CircuPool RJ-45 Plus
I would not be too quick on trying to lower the CYA for your climate. See how much chlorine you are using to get an idea if that level of CYA is helping or not.
You might want to install a Pentair IC60 SWG as that would fit in nicely with your pool.
You might want to install a Pentair IC60 SWG as that would fit in nicely with your pool.
You could consider using a pool cover to eliminate evaporation and since I presume you don't need any solar heating, you can use a white or reflective opaque cover. That will prevent heating of the pool and will also cut down on chlorine breakdown from sunlight.
For various reasons, I do not want a cover. The SWG might be a consideration, however. My existing CYA would be in the range for a SWG. Is the IC60 the best choice given my pool size (38,000 gal) and using an Easy Touch 8 controller?
As shown in this thread, the IC60 is the most economical and in your case with your larger pool it's essential for you to get this largest unit. It outputs 2 pounds of chlorine every 24 hours. Type the following into Google search:
and you will get
so 0.26 ppm FC per hour from the IC60 in your pool when it is on (at 100% ontime). With your hot climate, you'd probably want your CYA even higher at 80 ppm after you get the SWCG. As shown in this post, the FC loss per hour at 80 ppm CYA with 4 ppm FC might be around 0.12 ppm though this varies by pool, but your SWCG should be able to keep up without a problem. In theory, you may be able to run with 0.12/0.26 = 46% ontime during the peak daylight hours, but you'll just need to adjust this until it works well for your pool so that you still have at least 4 ppm FC when the SWCG turns on at the start of a day.
The bigger concern regarding the evaporation is not just the water waste but the refill with water that the 2014 Riverside Water Quality Report shows Total Hardness at 208 ppm and since Calcium Hardness (CH) is typically 70% of Total Hardness, that would make CH at around 145 ppm so actually not so bad. As shown in this pan evaporation list, Riverside in May through September averages 9" per month or 0.3" per day evaporation. If you have a 6' deep end and a 3' shallow end so average pool depth of 4.5', then your CH will increase by 145*((9/12)/4.5) = 24 ppm per month so over 6 months that's 145 ppm. So long as you dilute some with winter rain overflow each year, you should be OK.
and you will get
so 0.26 ppm FC per hour from the IC60 in your pool when it is on (at 100% ontime). With your hot climate, you'd probably want your CYA even higher at 80 ppm after you get the SWCG. As shown in this post, the FC loss per hour at 80 ppm CYA with 4 ppm FC might be around 0.12 ppm though this varies by pool, but your SWCG should be able to keep up without a problem. In theory, you may be able to run with 0.12/0.26 = 46% ontime during the peak daylight hours, but you'll just need to adjust this until it works well for your pool so that you still have at least 4 ppm FC when the SWCG turns on at the start of a day.
The bigger concern regarding the evaporation is not just the water waste but the refill with water that the 2014 Riverside Water Quality Report shows Total Hardness at 208 ppm and since Calcium Hardness (CH) is typically 70% of Total Hardness, that would make CH at around 145 ppm so actually not so bad. As shown in this pan evaporation list, Riverside in May through September averages 9" per month or 0.3" per day evaporation. If you have a 6' deep end and a 3' shallow end so average pool depth of 4.5', then your CH will increase by 145*((9/12)/4.5) = 24 ppm per month so over 6 months that's 145 ppm. So long as you dilute some with winter rain overflow each year, you should be OK.
**Whew** that is lot of information to digest, and I appreciate it. Looks like the IC60 is the way to go. Hopefully this winter will provide some rainwater to dilute, so fingers crossed.
60 CYA is easily managed. You may actually find the daily FC losses to be less than they would be at 40 or 50 CYA. You've got a huge pool, so even with perfectly balanced chemistry, it's going to take a lot of anything to maintain FC.
You should be grateful you weren't left with triple digit CYA. I started out in the 220-240 range - and water restrictions were in place then, too.
You should be grateful you weren't left with triple digit CYA. I started out in the 220-240 range - and water restrictions were in place then, too.