High CH, need advice on pool draining options.

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Oscar G.

Gold Supporter
Jun 21, 2019
135
Gilbert Arizona (Phoenix suburb)
Hello all, my CH has slowly increased to 920 per my latest test and I am going to drain the pool this winter to get it back down to a reasonable level. I have been researching the forums and pool school and I see that there are options for how to go about draining the pool .

With such high CH, does it make any sense to do a water replacement or should I drain the majority of the pool to prevent having to repeat the process in a few months?

Latest test results
CH 920
TA 100
FC 6
CC .5
CYA 60
PH 7.8

Thanks for any advice you can offer. :)
 
Be mindful of the surrounding water table if you're doing this in the rainy season. If there is enough ground water around the pool, it can float an empty pool right out of the ground. Pardon that scare if that is not an issue where you live.

In addition to the floating issue, relieving the pressure applied by the water to the finish can sometimes cause problems (blistering of the finish, pop-offs, that sort of thing). This is more likely with aging plaster than it is with newer pebble.

I have gone to great lengths to never have to empty my pool (by controlling CH and salt accumulation). But if I ever did need to exchange water, I'd use the "no-drain" method, unless the fill water made that impossible (which is why Dave is asking about it, I'm gonna guess)...
 
Dirk said:
I have gone to great lengths to never have to empty my pool (by controlling CH and salt accumulation).
Click to expand...
How do you control CH accumulation? I've always though that a pool owner was at the mercy of their fill water. Mine's on an autofill, so every day when water evaporates (a lot here in AZ) I get more fill water added. Is there a way to control CH accumulation other than covering the pool to prevent evaporation?
 
Tough to do out in Sunny AZ with already high fill CH in many cases. Mechanically, some folks have pretty good luck with roof runoff, but there is no way to do it chemically.

Oops! I should've indicated a water softener into an autofill is a likely solution, if powerful enough
 
Last edited:
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Oscar G. said:
Hello all, my CH has slowly increased to 920 per my latest test and I am going to drain the pool this winter to get it back down to a reasonable level. I have been researching the forums and pool school and I see that there are options for how to go about draining the pool .

With such high CH, does it make any sense to do a water replacement or should I drain the majority of the pool to prevent having to repeat the process in a few months?

Latest test results
CH 920
TA 100
FC 6
CC .5
CYA 60
PH 7.8

Thanks for any advice you can offer. :)
Click to expand...
I see you live near me, and that you have an SWCG. Another question which might be relevant is whether you are getting scaling on your salt cell because of your high CH. If so, I think I would drain in the winter. Our fill water here is pretty high - I tested mine in Chandler recently and it's about 190-200.
 
Dirk said:
Be mindful of the surrounding water table if you're doing this in the rainy season. If there is enough ground water around the pool, it can float an empty pool right out of the ground. Pardon that scare if that is not an issue where you live.

In addition to the floating issue, relieving the pressure applied by the water to the finish can sometimes cause problems (blistering of the finish, pop-offs, that sort of thing). This is more likely with aging plaster than it is with newer pebble.

I have gone to great lengths to never have to empty my pool (by controlling CH and salt accumulation). But if I ever did need to exchange water, I'd use the "no-drain" method, unless the fill water made that impossible (which is why Dave is asking about it, I'm gonna guess)...
Click to expand...
I'm in the Phoenix area so I don't think I have to worry about floating the pool but I will definitely check with my pool builder to confirm. I did speak to Pebble-tec and they advised me to wait until temps are 60-85 deg F and it will be fine. How are you controlling CH?
 
DanF said:
I see you live near me, and that you have an SWCG. Another question which might be relevant is whether you are getting scaling on your salt cell because of your high CH. If so, I think I would drain in the winter. Our fill water here is pretty high - I tested mine in Chandler recently and it's about 190-200.
Click to expand...
I did have to acid wash the cell but it wasnt that bad. No signs of scaling anywhere else though.
 
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The evaporation rate here in the desert is insane. In Tucson we lose an average of 15 inches of water in the month of June alone! Without auto fill, a 10 foot deep pool would be completely empty before the end of a year.
To avoid calcium buildup, I have the auto fill connected to a water softener. Without it the CH would double in a year.
 

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I've sort of lucked out with salt. The salt accumulation seems to be a wash with the water that is replaced naturally due to rain. I actually had to add a bag a while back. More on that in a bit.

My fill water is about CH:350. I control CH accumulation by topping off the pool with soft water (CH:0). I dug up my auto-fill line and re-plumbed it to my house's water softener. I've been maintaining a CH <400 for several years now.

I have a PoolMiser auto-fill system, which houses my overflow exit point. The small well this system is in connects to the pool via an equalizer tube that enters the pool a few feet below the surface. This is theoretical, but I believe this is what's happening: When it rains the fresh water floats on top of my saltwater pool. With conventional overflow systems, like a hole or grate in the edge tile or skimmer, a lot of the fresh water would drain right off the surface. But because my equalizer tube is well below the surface, the fresh water rain forces the salt water out of my pool from below, allowing the fresh water to mix in. Every time it rains, I'm getting a mini no-drain water exchange, and it is this effect plus the water softener that is keeping my CH and salt accumulation in check.

Additionally, if I test and find elevated levels of salt and/or CH, I'll manipulate the rain water exchange. Just before a prediction of heavy rain, I'll use the overflow tube in my PoolMiser well to lower the pool water level a few inches. The rain replaces the drained water, and that brings down the CH and salt even more effectively than what I described above. I lose a little CYA in this process, but that is a very small price to pay.

So it's three MOs at work.
 
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chiefwej said:
The evaporation rate here in the desert is insane. In Tucson we lose an average of 15 inches of water in the month of June alone! Without auto fill, a 10 foot deep pool would be completely empty before the end of a year.
To avoid calcium buildup, I have the auto fill connected to a water softener. Without it the CH would double in a year.
Click to expand...
I know what you mean. The pool was just built last summer and opened in July, so in 14 months my CH is almost 1000. I've considered filling from a water softener as well and may do that at some point.
 
Dirk said:
I've sort of lucked out with salt. The salt accumulation seems to be a wash with the water that is replaced naturally due to rain. I actually had to add a bag a while back. More on that in a bit.

My fill water is about CH:350. I control CH accumulation by topping off the pool with soft water (CH:0). I dug up my auto-fill line and re-plumbed it to my house's water softener. I've been maintaining a CH <400 for several years now.

I have a PoolMiser auto-fill system, which houses my overflow exit point. The small well this system is in connects to the pool via an equalizer tube that enters the pool a few feet below the surface. This is theoretical, but I believe this is what's happening: When it rains the fresh water floats on top of my saltwater pool. With conventional overflow systems, like a hole or grate in the edge tile or skimmer, a lot of the fresh water would drain right off the surface. But because my equalizer tube is well below the surface, the fresh water rain forces the salt water out of my pool from below, allowing the fresh water to mix in. Every time it rains, I'm getting a mini no-drain water exchange, and it is this effect plus the water softener that is keeping my CH and salt accumulation in check.

Additionally, if I test and find elevated levels of salt and/or CH, I'll manipulate the rain water exchange. Just before a prediction of heavy rain, I'll use the overflow tube in my PoolMiser well to lower the pool water level a few inches. The rain replaces the drained water, and that brings down the CH and salt even more effectively than what I described above. I lose a little CYA in this process, but that is a very small price to pay.

So it's three MOs at work.
Click to expand...
That's an awesome game plan! I may fill my pool from a softener at some point if the draining thing is a hassle.
 
Getting a solar cover and putting it on the pool in the Spring (April and May) and the fall (Sept to November) really reduces evaporation. I am also installing a water softener just for the pool. My wife calls the water 'dry' when the CH gets high!
 
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Marty - I would appreciate your posting the details of your softener install once you get around to doing it. I may consider it also.

I guess the payback from a softener on the autofill would be reduced (or eliminated) annual/biannual draining requirements...which would avoid the water cost, and the startup chemicals (MA, CYA and salt in your case)?
 
You bet. It is not economic. It is far cheaper to just replace the water every 16 months or so. My CH goes from 250 to above 800 ppm in that time frame.
 
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I used my house's softener. It's also protecting my indoor plumbing fixtures, toilet and glass shower walls. It's a nice convenience. So far, my pool's evaporation and house needs have not exceeded its capacity. I don't bother to do the math. The salt is cheap. Water where I am is not. Neither is an amount that is going to break the bank, just another pool expense, I figure. I'm so far ahead of the game since I switched from pool guy to TFP that I can afford the convenience of not having to drain the pool, and not having to worry about calcium collecting on its finish (which it did before I added the softener).

Here is the story of my softener hookup. This thread is rather obnoxious, not only in length, but how it meanders around dozens of my first-time-pool-owner blues, all the way through the softener hookup and later how I tried out roof water collection as another way to control CH. Marty and Matt (joyfulnoise) helped me a lot in figuring a lot of stuff out, including how the softener was going to work out. The actual softener hookup saga starts at post #76.

#76

Some of the posts refer to testing the water after the softener and getting CH:60. I think that was user error (or hard water still in the pipes when I ran that test). Subsequent testing revealed much closer to CH:0.
 

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