I wouldn't worry about regen frequency, unless you start going over 20-30 days. There are those that will argue frequency, but unless you have really nasty (dirty) water, I wouldn't worry about it too much. My family's use means I will regen about every 5-18 days.
A 1.5 cu ft resin tank will allow better salt usage, as Tom and others have said; I went with one for that very reason. The price difference is negligible.
The rinse water will contain about the same chlorine as the incoming water; chlorine will remain in solution unless you remove it chemically, or unless it precipitates out once exposed to air. I'm not a pool expert, but I seem to recal reading somewhere that soft water is not good for a gunite pool...
Your raw water is likely to have more sodium than the 20 mg/l. And IIRC, it's the chloride that corrodes SS, or more than sodium does. IMO it would take either a long time to corrode SS enough to cause a problem in a water heater and I wouldn't worry about it IF I had to have a SS water heater.
Originally Posted by cgarai
Over running the SFR is not a good idea and you should get the correct sized softener and program it for the best salt efficiency it can give you. That's because you should want to get it done right the first time and gt on with life.
An metered 8 day regeneration is fairly efficient and if you program at 60 gals/day/person there won't be much capacity left in 8 days to worry about. To change to a larger tank measn you have to change parts in the control valve also. And the plumbing and buy more resin. It's a bad idea.
The softener drain water needs to go to the septic/sewer system, it is not good for a pool and will mess up the water chemistry due to the hardness possibly but more likely the salt.