Why so much acid demand?

davethomaspilot

Bronze Supporter
Aug 30, 2015
95
Apex,NC
Just following up--using a ph setpoint of 7.6 really reduced the required acid. Only a quart or two since the post and pH is tightly controlled by the Intellichem system, at least when the pump is running (it always is, and has been for a while when we are in the pool.

For what it's worth, chlorine demand also continues to be quite low while maintaining ORP > 700.

We've never noticed any harshness or swimsuit deterioration over the last 4-5 years. Maybe because that's because we're never in the pool more than an hour a day. (Or maybe we just have tough old skin and swim alot without suits!) but for whatever reason, it's not an issue for us.

I've always gone with 0 CYA. The problem I have with adding CYA is that I can't take it out, and I'm quite happy with having none. ORP probes are more sensitive, and much less FC is needed for the same sanitation level. Less chlorine means less to be destroyed by sunlight.

Yes, I recall some anecdotal stuff about the CYA somehow shading/shielding to result in lower chlorine usage, but, again, I'm really happy with the small amount I've been using for several years.

Thanks again!





Thanks again.
 

scottts

Gold Supporter
Nov 13, 2019
160
Gilbert, AZ
Just following up--using a ph setpoint of 7.6 really reduced the required acid. Only a quart or two since the post and pH is tightly controlled by the Intellichem system, at least when the pump is running (it always is, and has been for a while when we are in the pool.

For what it's worth, chlorine demand also continues to be quite low while maintaining ORP > 700.

We've never noticed any harshness or swimsuit deterioration over the last 4-5 years. Maybe because that's because we're never in the pool more than an hour a day. (Or maybe we just have tough old skin and swim alot without suits!) but for whatever reason, it's not an issue for us.

I've always gone with 0 CYA. The problem I have with adding CYA is that I can't take it out, and I'm quite happy with having none. ORP probes are more sensitive, and much less FC is needed for the same sanitation level. Less chlorine means less to be destroyed by sunlight.

Yes, I recall some anecdotal stuff about the CYA somehow shading/shielding to result in lower chlorine usage, but, again, I'm really happy with the small amount I've been using for several years.

Thanks again!





Thanks again.
Man, I wish I could get my ORP to 700+. With an FC of 7.5ppm, CYA 30, my ORP is 580-610. The harder I run my intellichlor the more ORP drops. I guess I need to let CYA drop all the way to 0 to see if that fixes it. I've been floating a puck or two to keep CYA at 20-30.

Sorry for jumping in.
 

davethomaspilot

Bronze Supporter
Aug 30, 2015
95
Apex,NC
I no longer use the chlorine tank on the Intellichem. Instead, I have three, five gallon containers that I refill when all three are empty.

I'd estimate five gallons of 12% sodium hyperchlorite lasts 2-3 weeks. That's with a 17000 gallon pool and spa, mostly sunny weather, southeast summer weather conditions (not dry).

What usage is typical with 30% CYA?
 

mgtfp

Bronze Supporter
Mar 5, 2020
440
Melbourne, Australia
For your pool size, those 5 gallons would be equivalent to about 37ppm of FC over 2-3 weeks, i.e roughly 2ppm of FC per day. That's at the low end of normal I'd say, I think most TFP pools run between about 2-4ppm per day, depending on UV and bather load.

I have a SWG that creates in summer about 2-2.5ppm of FC per day. My CYA is in summer between 60 and 80. Now, I'm in winter mode with CYA around 30, and my SWG is creating maybe about 0.5ppm per day, probably less since the SWG output at low temperatures should be lower than the nominal output.