What if CYA is 53ish?

[psbailey]

I was looking at Ben's chart and I perceived a gap.

The chart tells you the FC range if your CYA is b/w 30 and 50. The chart then gives FC recommendations for CYA levels b/w 60 and 80.

What if your CYA is b/w 50 and 60, as mine is about 53 (its closer to 50 than 60)? Do you round down (or up) to the closest level?

Maybe I'm reading too much into the chart, as well.

Thanks,

Paul

[CarlD]

Live in the overlap!

30-50 CYA: 3-6ppm FC
60-90 CYA: 5-10 ppm FC

You'd want to be in the 5-8 range--after all, it's a Best GUESS table!

[waterbear]

How did you get a reading of 53? The CYA test does not have that much precision! Call it 50! Someone else might get a different reading because the test is subjective!

[psbailey]

Oh, yeah. 53 is a total SWAG. The water line was closer to 50 than 60, that's all.

I completely agree that the test is very subjective. It depends upon the tester's eye sight, the current conditions (cloudy, sunny, etc.) and on and on and on. I wish it weren't so.

Thanks for the reply!

Paul

[CarlD]

Paul:
Evan didn't tell you anything that contradicts my advice. That's why there's overlap.

I look at the CYA range, and the matching residual chlorine range, and try to match my residual to whatever end of the CYA range I'm at. So if 30-50 is 3 to 6, I prefer 3 for 30, 4.5 for 40, and 6 for 50. It's not hard and fast, probably isn't even necessary, but it works for me. Either way, you're at the high end of the 30-50 and the low end of 60-90. So use the residual levels for those ends of each.

Just don't get confused by it. It just SOUNDS contradictory.

[waterbear]

Carl hit it right on the head again, as usual!