Ideal numbers for SW Pools??

Andiejj

Well-known member
Jul 19, 2007
188
Katy, TX
#1
Anyone willing to run down the ideal numbers when testing? Sometimes I see responses that say "xyz.... is ideal for a salt water pool". Thanks!
 

The Mermaid Queen

TFP Expert
LifeTime Supporter
Mar 28, 2007
2,522
Northern KY
#2
some things, like CYA, depend on your system. Check your manual to find the amount. Then use Jason's calculator to find your optimal FC for a SWG.

pH 7.2 - 7.8 (but most prefer 7.4 - 7.6)
ch don't know!
TA 90-120
salt usually around 3000, again, check your manual.

Hope this helps!
 
G

Guest

#3
For a salt pool these numbers are very good at helping prevent pH rise and maintaining a proper chorine level.
FC 3-5 ppm
CC < .5 ppm (If it's higher shock with liquid chlorine to about 15-20 ppm)
pH 7.6 (when it hits 7.8 add enough acid to drop it to 7.6 and no lower)
TA 70-90 ppm before stabilizer correction (this will help lower the amount of CO2 outgassed and help slow the eventual pH rise)
CH 250 or so for vinyl or fiberglass, 300 for plaster. Slighly higher is OK but check your cell for scaling regularly.
CYA 70 ppm or slightly higher unless you have one of the 'Australian style' SWGs that recommend 80-100 ppm CYA. In that case 80-90 is a better choice
Borates 50 ppm (when they drop to 30 ppm bring them back up to 50). This will help stabiize the pH and reduce acid consumption and sanitizer demand.

I have seen these numbers work on my own pool and my customers pools. The most important numbers are the FC, pH, TA, and CYA. Borates do make a big difference. I would definately recommend them. Calcium is more important for plaster pools. You want the calcium saturation index to be on the slightly scaling side. In a fiberglass or vinyl pool slightly aggresive to slightly scaling is ok. Actually pH is the most important thing to watch for scaling or agressive water and temp the second most imortant. If your calcium is in the ballpark then don't worry about it too much. If it is very low or very high then it can be problematic.
 

bluenoise

LifeTime Supporter
Jul 25, 2007
187
Alamo, CA
#4
waterbear said:
For a salt pool these numbers are very good at helping prevent pH rise and maintaining a proper chorine level.
FC 3-5 ppm
CC < .5 ppm (If it's higher shock with liquid chlorine to about 15-20 ppm)
pH 7.6 (when it hits 7.8 add enough acid to drop it to 7.6 and no lower)
TA 70-90 ppm before stabilizer correction (this will help lower the amount of CO2 outgassed and help slow the eventual pH rise)
CH 250 or so for vinyl or fiberglass, 300 for plaster. Slighly higher is OK but check your cell for scaling regularly.
CYA 70 ppm or slightly higher unless you have one of the 'Australian style' SWGs that recommend 80-100 ppm CYA. In that case 80-90 is a better choice
Borates 50 ppm (when they drop to 30 ppm bring them back up to 50). This will help stabiize the pH and reduce acid consumption and sanitizer demand.

I have seen these numbers work on my own pool and my customers pools. The most important numbers are the FC, pH, TA, and CYA. Borates do make a big difference. I would definately recommend them. Calcium is more important for plaster pools. You want the calcium saturation index to be on the slightly scaling side. In a fiberglass or vinyl pool slightly aggresive to slightly scaling is ok. Actually pH is the most important thing to watch for scaling or agressive water and temp the second most imortant. If your calcium is in the ballpark then don't worry about it too much. If it is very low or very high then it can be problematic.
I've been closing in on these numbers, but I have a question about CSI and my plaster pool. When I plug these numbers into the Pool Calculator, I get a CSI of -0.14 at 85 degrees temperature. Since the recommendation is to have the CSI slightly above 0.0 with a plaster pool, how should I adjust the targets to achieve this CSI?

Also, how do I test for borates?
 

JasonLion

TFP Expert
Platinum Supporter
LifeTime Supporter
May 7, 2007
37,879
Silver Spring, MD
#5
I would balance the CSI by raising CH.

There are test strips for borates that seem to be good enough, AquaChek I believe. LaMotte also makes test strips that are better, but they appear to be difficult to find.
 

bluenoise

LifeTime Supporter
Jul 25, 2007
187
Alamo, CA
#6
JasonLion said:
I would balance the CSI by raising CH.

There are test strips for borates that seem to be good enough, AquaChek I believe. LaMotte also makes test strips that are better, but they appear to be difficult to find.
All else being equal, it appears I'd need to put the CH at 410 to get to 0.01 on the CSI. Is that going to cause scaling problems for my SWG's cell?
 
G
#7
CSI is only a guide. I would not lose sleep over a -.14 CSI. pH is the main factor that will change CSI with temp the second factor. Unless the numbers are REALLY out of whack you are fine! IMHO, a slightly agressive number such as you have will help prevent scaling of the cell. People get too hung up on saturation index numbers. IT IS ONLY A GUIDE and not really much more useful than a TDS reading, IMHO.