Ideal numbers ?


LifeTime Supporter
Jul 23, 2007
Fremont, CA
There seem to be a general consensus on what the ideal numbers should be for a given pool setup for some paramenters but a wide array of numbers is thrown out for some others.. here is what I could glean from the forum so far for gunnite/Plaster pools with no SWCG

CYA : 50 +/- 10
TA : 150 +/- 50
pH : 7.5 +/- 0.2
CH : 220 +/- 20
FC : 4ppm +/- 1

Comments/ suggestions are welcome


TFP Expert
Platinum Supporter
LifeTime Supporter
May 7, 2007
Silver Spring, MD
There are several different ranges for most of the numbers depending on several factors. My suggestions are:

CYA - either 30-50 (normal & ORP) or 60-80 (SWG or lots of sun) or 70-90 (really really lots of sun)
TA - either 70-90 (bleach or SWG or lots of aeration) or 100-120 (trichlor or dichlor) or as low as 50 with borates
PH - either 7.4-7.6 (normal) or 7.6-7.8 (lot and lots of aeration)
CH - either 0 (vinyl) or 100-150 (spa) or 200-400 (plaster, pebble, stone) (fiberglass is unclear, 100+ or 200+?)
FC - depends on CYA, see my Pool Calculator for suggestions (link in my signature)

For a plaster pool I would fine tune the CH level based on the saturation index.

Many of these numbers can go outside those ranges and still be fine and there are a few special situations where other numbers might be required.