Reduction of CH

[chem geek]

Other than drain/refill with low CH water, the other way to reduce CH is putting the water through a water softener (ion exchange resin or equivalent). This is usually impractical for a full volume of pool water, but is useful for fill water once a pool is already filled.

However, even high CH should not really be a problem because one can significantly lower the TA level to compensate and keep the pH at 7.5 or below. This will prevent scaling and the lower TA level will help reduce the tendency of the pH to rise. The only downside to the low TA would be if you used an acidic source of chlorine such as Trichlor since the pH would get lowered faster in that case, but this just means more frequent monitoring of pH. If you use chlorinating liquid or bleach, then there is no problem as the pH is usually stable or rising, not dropping.

The "standard recommended" values for TA and CH are based on handling a variety of chlorine sources and on trying to give a relatively narrow set of ranges for the parameters. However, water with a TA of 50, CYA of 30, pH of 7.5, and CH of 700 is perfectly balanced (saturated with calcium carbonate). So unless the CH is extraordinarily high, say 1500, keeping a lower TA is usually all that is needed.

Richard

[njpool]

Other than drain/refill with low CH water, the other way to reduce CH is putting the water through a water softener (ion exchange resin or equivalent). This is usually impractical for a full volume of pool water, but is useful for fill water once a pool is already filled.

Why is it "usually impractical"? Is it because the softener would have to be constantly recharged with brine?

I ask because my parents operate a pool at their beach resort in the Philippines and have issues with cloudiness. The pool man needs to constantly add pH down/acid to stop it from clouding up. I figure it is due to the well water they use, which is rather hard. I believe as the pH goes up, the calcium would 'precipitate' out. I suggested they put in some kind of water softener to reduce the hardness, but not sure how to configure it. I read that you could use zeolite as the exchange medium. Currently, they have a DE filter. If you added a sand filter to the mix and use zeolite instead of normal sand, I would think the only other issue is how to plumb the system for the recharge cell.