Does pool water need to be replaced?

JT2006

LifeTime Supporter
Jul 1, 2013
125
Southwest Arizona (Yuma)
#1
I'm still a newbie and learning but this doesn't make a whole lot of sense to me?

I live in Southwestern Arizona so freezing is not an issue. My buddy and I were talking this morning and he says he plans on draining his pool next weekend. When I asked why he said to "replace" the water?

I have never heard of this but he says that you are supposed to do this every year? Because the pool water gets contaminated with minerals and other biproducts of chlorine?

Is this accurate?
 

Smykowski

TFP Expert
LifeTime Supporter
#2
In a properly maintained pool, no. However, if the CYA gets too high, or if the CH gets too high, the only way to remove it is through water replacement.

Edit: I guess your statement is technically correct. If the sole source of chlorination is Dichlor, trichlor, or cal-hypo, CYA and CH are the byproducts of chlorination, and yes, they need to be removed through water replacement. If you only use liquid chlorine (like many of us do), the only byproduct is salt, which can be left in the water.
 

jblizzle

Mod Squad
TFP Expert
LifeTime Supporter
May 19, 2010
41,197
Tucson, AZ
#3
Given the hard water we have, high evaporation rates, and lack of rain, the CH will tend to climb faster than other parts of the country. As it get higher, you can compensate and avoid problems by keeping the TA and pH a little lower. But, eventually this becomes impractical as the CH approaches 1000ppm and you will need to drain and replace water. Every year seems pretty excessive though for CH getting too high unless you are also using cal-hypo. I would guess the CH will climb pretty high in 3-5 years though.

This all goes back to understanding and testing the chemistry and knowing what your pool needs.

If you are using the wrong kind of chlorine, then the CH and CYA will get too high and require water replacement .... especially in our environment where we do not get a lot of rain dilution and we do not partially drain for winter closing.
 

Toesinsand

Active member
Nov 5, 2013
27
Houston, Texas
#5
I was curious if anyone has ever done the math and cost analysis on using a RO water maker for evaporation replacement in a desert environment like Arizona. I guess the biggest problem is what to do with the waste water from it. If you add 100 gpd of pure calcium free water to your pool every day to replace evaporation you have about 200 gpd of water to do something else with. It is actually good filtered water, just not as pure as the RO. I don't have the problem where I live. My tap water CH is 60. Alk is up around 330 though.
 

jblizzle

Mod Squad
TFP Expert
LifeTime Supporter
May 19, 2010
41,197
Tucson, AZ
#6
There are RO companies that do treatments on pools in limited markets (PHX, Tucson, So Cal) ... problem is it costs over $400 and you still loose 10+% of the water. So it is nearly always cheaper to dump and refill.

Now if you are talking about using a private RO system or water softener just for top off water, that can help slow the CH rise. What some members do is capture as much rain water off their houses as they can and divert it into the pool ... free 0 CH water. Just very rare here in AZ ;)
 

Toesinsand

Active member
Nov 5, 2013
27
Houston, Texas
#7
Yes, I was just thinking it would be good for top off. I have two RO units in my house, one for drinking water and another for top off water for my salt water reef aquarium. You can get a pretty basic RO system making 150 gpd for less than $200. If you just top off with RO, your calcium level should not rise at all. It is like replacing with rain water.