Effect of CYA levels

dschlic1 · Oct 8, 2009

I have a SWCG and normally try to run my CYA level between 60 to 80 ppm. During the last couple of months, I noticed that to maintain an FC level above 3 ppm I had to increase the setting on the SWCG. At the time I thought that this was due to the summer sun.

Like just about everyone, I have had trouble getting accurate readings on the CYA test. The readings depend on many factors including ambient lightin conditions. I check the CYA level at the beginning of each month. Last month, for some reason the reading was very low ~30 to 40 ppm. I promptly added enough CYA to bring the level up to 70.

Anyway my FC level jumped from 3 to 5 ppm in less than one week after adding the CYA. This is dramatic proof of the effect CYA has!

polyvue · Oct 8, 2009

dschlic1 said:
Anyway my FC level jumped from 3 to 5 ppm in less than one week after adding the CYA. This is dramatic proof of the effect CYA has!

Indeed. On my fantasy wish list is a more precise measurement of CYA than the "visual" turbidity test that's so prevalent and a truly smart SWG controller that could adjust itself based on an internal, reliable measurement of free chlorine. Shouldn't have to go into "setup" mode to calibrate the SWG every time the CYA changes a bit, or when any number of other factors change (solar cover, bather load, more/less sunshine.) They can send people & probes to the moon and to the stars but they can't make a mass-market instrument that measures free chlorine? :grrrr:

dschlic1 · Oct 9, 2009

There are instruments that measure free chlorine. They just cost $1000 to $1500 :shock:

polyvue · Oct 9, 2009

dschlic1 said:
There are instruments that measure free chlorine. They just cost $1000 to $1500

Somehow I just knew that would be the price... :wink:

My pool builder must have screwed up in not offering it.

Now, I guess the question is this: is the instrument reliable enough to be used as controller input to a SWG? Hmmmm? :shock:

Bama Rambler · Oct 9, 2009

We use chlorine instruments where I work that are good enough for control but you'll have to add a zero to the afore mentioned price to get one. Yeah $10,000.00 for one of them.

polyvue · Oct 9, 2009

Bama Rambler said:
We use chlorine instruments where I work that are good enough for control but you'll have to add a zero to the afore mentioned price to get one. Yeah $10,000.00 for one of them.

Bama... I said it'd be great if they made a mass-market instrument. For that money, why not get three or four?! One on the pool, one on the shelf, and two for Christmas presents to deserving friends or relatives... heh heh :mrgreen:

dschlic1 · Oct 12, 2009

Hach makes an online chlorine analyzer for about $2,500 which also includes a pH instrument. Others make similiar units Google "Amperometric Chlorine".