Does a higher CYA in summer have advantages?

[Ronald U.]

Greetings. I seem to understand that raising my CYA for summer full sun will be an advantage. I am currently CYA 40 and lose 3 - 3.5 FC daily. If I move CYA to 50 or 60, will my daily expense of chlorine go down? Thank you.

pH 7.7
FC 6.0
CC 0.5
TA 120
CH 250
Borate 40
CYA </= 40
Water Temp 82F

 

[Richard320]

Yes.

It probably won't be as large a savings as you are hoping, though. There's a couple graphs in this thread if you're the scientific type that show the differences.

I'd still move it up to 50 now which will leave a little room to use pucks if you leave town during the summer.

 

[woodyp]

50 minimum....and realize that will most likely drop around 5 ppm per month over summer with use---splash out and such.

 

[Ronald U.]

That was a seriously deep thread. I was submerged for a long time and just came up for air. There was a graph that I think you were referring to showing chlorine loss/hr at varying CYA and chlorine ion levels. I still don't clearly see the advantage of a higher summer CYA.

 

[jblizzle]

Think of it this way. The cya will protect a percentage of your chlorine from the Sun every day. The higher the cya level the higher percentage that is protected. So even though you're absolute FC PPM numbers are higher you should be losing less to the sun each day.

 

[Richard320]

That was a seriously deep thread. I was submerged for a long time and just came up for air. There was a graph that I think you were referring to showing chlorine loss/hr at varying CYA and chlorine ion levels. I still don't clearly see the advantage of a higher summer CYA.

You mean this?

The vertical scale is half-life. You gain an extra hour or two at the higher CYA, which could add up to substantial savings over the course of the sumnmer. But you can also see how the slope flattens out, so raising CYA above 70 gains you very little.

 

[Ronald U.]

Thanks. I had focused on a different graph but I see your point. Plus I read further in the deep thread that chem geek refers to as-yet unexplained empirical data that chlorine loss does lessen at higher CYA. I shall raise my CYA to 50 and join the club.

 

[Poolzzz]

Based on the chart I don't see the savings actually.

Take a CYA of 30 where you need 5 FC (middle of 4-6). Then compare a CYA of say 50 where you need 7 FC (middle of 6-8).

The CYA=30 case the half life is 5 hours, for the CYA=50 it raises to 7 hours. That's a 40% improvement which sounds great EXCEPT you also need 40% more chlorine!

 

[Ronald U.]

Once you have bumped up to new target FC, you will only be replacing daily loss, which supposedly is less (?).

 

[jstblush]

Just raised my CYA from 40 to 50 about half an hour ago. I decided last year I was going to see what happens with FC usage with the higher CYA. We'll see...
Sherry

 

[Poolzzz]

Once you have bumped up to new target FC, you will only be replacing daily loss, which supposedly is less (?).

Yes, but based on the chart the daily loss nets out to be the same.

I'm only commenting on the chart info, not what happens in real life which may have factors the chart doesn't reflect.

 

[dschribs]

I've upped my CYA to 50 this year. I was at 30 last year. I've already noticed I'm using less chlorine. I wa afraid to go to high because of all the CYA horror stories on here but I think I've now found the "sweet spot".

My pool gets full sun from sun up to sun down.

 

[Poolzzz]

What FC were you running last year and now this year?

 

[andysousa]

I'd still move it up to 50 now which will leave a little room to use pucks if you leave town during the summer.

This statement confuses me a little (albeit I am a noob). I thought pucks raised the cya hence why I should always be using liquid chlorine?

 

[elight]

This statement confuses me a little (albeit I am a noob). I thought pucks raised the cya hence why I should always be using liquid chlorine?

I think he's saying that at 50, if you need to use pucks temporarily (e.g., out of town for a week or two), there's still a little room for CYA to be increased without it being dangerously/ineffectively high.

 

[Richard320]

I think he's saying that at 50, if you need to use pucks temporarily (e.g., out of town for a week or two), there's still a little room for CYA to be increased without it being dangerously/ineffectively high.

Precisely.

And there's no crime in using trichlor to chlorinate if you need the extra CYA and acidity.
That's the essence of TFP: only add what you need and know what you're adding.