JasonLion,
Thank you for your clear and polite response, I did learn from what you wrote.
One query I would like you to help me with is where you write,"The "Stabilization with Cyanuric Acid" chart is not accurate. The effect is similar to what they show, but higher CYA levels provide more protection from sunlight than that chart indicates", can you direct me to a link for this type of chart? I would be interested to view it.
I fully agree with you when you state "It is simple enough to raise the FC level to compensate." Albeit so long as ones SWG is large enough.
We have the PoolPilot Total Digital SC-60. The ORP is set to cut off at 700, the power setting is 2. In our 10,000 gal pool with salt at 3500 and CYA at about 30 (allowable per their manual), and running for 4 1/4 hours (a 1.3 turn), from 11 am to 3:15 pm, it maintains a FC of 5, which seems to hold throughout the day. ph is 7.4, alkalinity 70, borates, 50, calcium 600, av.temp 84.
The ORP reading normally starts off at 660 or 665, then moves to about 685 by noon, dropping back to 660 by 1:30 pm, and closing at about 685 -690 depending if it is cloudy or not. If I turn it on at night for an hour, when I swim, it might be 705 or so. We use to have the pH at 7.5, but 7.4 gives a slightly better and more consistent ORP value.
If I run the unit longer say 12 hours, when the grandkids are in and out it most of the day, the ORP will rise to around 728 in the evening. The next morning it will start off at a higher reading say 685, but the FC will still be pretty rock constant throughout at 5.
I think more turns on the water have an effect on the ORP values, with possibly clearer water come less contaminants, yes no I am not sure, what do you think? The article is interesting, if I am reading it correctly, that lower CyA at 20 may produce more stable and potentially higher ORP readings. When and if I have the time I will try this out at 25 CyA, then, 20 CyA, reducing my FC to 4 then 3.5, and see if this is true. Also I will see if this creates any other problems and then report back, though that may be some time in the future, as I will let the CyA drop over time.
I do realize that ORP is not the be all and end all of sanitation, HOCl (as ppm Cl2) is more important. But if one can run at a lower FC then the cell unit might not be on all the time it is running and save on electricity. It is at least worth a try. I fully understand the argument for high CyA 60 - 80 for saltwater pools but here in Hawaii it does not seem to work as well.
I do not know why but algae starts to rear its ugly head, it most probably has something to do with high UV radiation in a short day year round at a 21.3 degrees latitude from the equator. A lower CyA of 30 with the above numbers works better for us (and my neighbours) with a FC of 5, drop it to 4 or below and trouble starts. I fully realize that other CyA numbers and FC numbers work perfectly well on the mainland and maybe in other parts of Hawaii.
So I will test their ideas; maybe they will bomb, possibly life may getter cheaper, who knows.
To those certain person(s) that may wish to repeat to me that my pool is not a science experiment I would like to kindly remind you it is our pool, so I think we are entitled to our little experiment. And what harm can come of it, maybe we will all learn something. As the old saying goes "A wise man does not know, and a fool will not listen". So I will try to learn something, by listening to this article.
Aloha
