Reverse Osmosis - Further Reading

Reverse osmosis (RO) is used to reduce Calcium Hardness (CH) and/or CYA in pool water.

For pool purposes, in layman's terms, RO is a type of very fine filtering performed via a mobile unit that essentially filters your water onsite through a special series of membranes designed to remove things such as CYA and CH from the water.

A lot of water is "wasted" in the process, but it still conserves more water than dumping and refilling a pool that has high concentration of CYA or CH. It is an ideal solution in drought areas with water restrictions.[1] R/O is a good way to recover water that would otherwise be dumped due to high CYA or Calcium Hardness and ergo is environmentally astute, especially where water conservation is an issue.

Reverse osmosis removes most of the dissolved solids from the water. That is everything: chlorine, TA, CH, CYA, Borates, Salt, everything.[2]

Water must be algae free to do a RO treatment.[3]

The equipment is specialized and pretty expensive for a large scale treatment like a pool so the service is not an option for most of the country. Usually only available where there is big demand due to higher temps, year round pool use or exceptionally hard water. Southern California, Arizona, and Dallas[4] are known to have Reverse Osmosis services.

RO is usually more expensive than doing a water exchange and you wind up dumping about 25-30% of your water anyway.[5] A RO operater posted that a decent RO will run anywhere from 5-15% waste.[6]

For most of the country a drain and refill or water exchange are the only options to reduce CH or CYA.

All chemical levels need to be checked and the water has to be rebalanced after a reverse osmosis treatment is completed on the water.