Reduce CH before SWG install?

[julesbravo]

My CH level right now is 875 and I'm having SWG installed soon. Should I reduce the CH by draining before installing the SWG? Out of the tap my CH is 400 so there'll be a limit of how low I can reduce it. Would it do much harm (other than wasting some salt) to wait until after the swim season? I have no problems with scaling.

 

[Rancho Cost-a-Lotta]

Welcome to TFP!

Can you confirm for us how your testing your water? CH alone is not a good indicator of scaling. SWG-related scaling usually occurs inside of the cell so pH and TA are contributing factors as well. Can you post a full set of results from your own test kit?

You would be a good candidate for adding a softened source of fill water for top offs. Any chance you can connect to a softener?

If your CH is truly 875 ppm, it's likely too high to effectively manage without some sort of scaling. I'll post a few articles that may help out.

Calcium Scaling

Calcium scale on your pool is something we all want to avoid. With some elbow grease and a pumice stone for pools we can help you remove this eyesore.

www.troublefreepool.com

Calcium Saturation Index (CSI)

How is CSI calculated? Very simple – use our PoolMath tool. To ensure long plaster life and save money, click here to learn more.

www.troublefreepool.com

Pool Care Basics Archives

Your one-stop shop for all things TFP to include: ABCs of Water Chemistry, Recommended Chemicals/Levels, Test Kits, Troubleshooting, and much more!

www.troublefreepool.com

 

[Rancho Cost-a-Lotta]

Additionally, you don't mention what type of pool you maintain. When you have time, please complete your signature:

Create Your Signature - Further Reading

www.troublefreepool.com

 

[julesbravo]

@Rancho Cost-a-Lotta Thanks for the reply! I've set up my signature and found the CSI section of the Pool Math Calculator. Here are my numbers:

• pH: 7.4
• TA: 100
• CH: 875
• CYA: 30
• Water Temperature: 82
• Salt: 0 (I don't have the SWG installed yet)
• Borates: 0 (I don't use borates)

This gets me a CSI value of 0.32. I'm thinking draining half the pool should be plenty to get this down, but I'm wondering if this is close enough that I can wait until after the swim season to do so.

 

[julesbravo]

It also looks like if I raise the salt level (which I will be doing when I add SWG) the CSI goes into an acceptable level.

 

[proavia]

With a fill water CH of 400 and a pool CH of 875, draining half the pool will result in a pool CH of 625-650.

With your high CH tap water, look into a whole house water softener solution and plan on plumbing the water softener to your autofill. Look for a 64k grain unit so it doesn't need to regenerate every few days.

Double check the CYA result you posted in post #4.

 

[julesbravo]

@proavia Thanks! We have a whole house water softener, but it's not plumbed into our autofill and would be majorly cost prohibitive to do so. Instead we plan on installing a rain water collection system and using that to fill when available. The CYA is updated. It's at 30.

 

[Rancho Cost-a-Lotta]

It also looks like if I raise the salt level (which I will be doing when I add SWG) the CSI goes into an acceptable level.

FYI...you do have salt in the pool now. Other chlorine products and muriatic acid leave salt behind as a byproduct. I only mention this as a reminder to get the Taylor K-1766 salt test kit and test before you add any salt to the pool. Many non-salt pool owners have found current salt levels well over 1000 ppm.

This gets me a CSI value of 0.32. I'm thinking draining half the pool should be plenty to get this down, but I'm wondering if this is close enough that I can wait until after the swim season to do so.

You can wait to exchange water, but you will (most likely) see scale with the current chemistry, especially at higher water temps. You may be able to reduce it scaling by aggressively (aeration/acid method) lowering TA to 50-60 ppm, but that may be a challenge depending on the TA of your fill/top-off water. As mentioned earlier (and by a fellow Arizonian), look into hooking up a soft water source (maybe even a $400 dedicated automatic softener).

Lower Total Alkalinity

A lower Total Alkalinity level can help a pool owner stabalize their pH increase. We'll explain how to lower TA with a little help from muriatic acid.

www.troublefreepool.com

Aeration - Further Reading

www.troublefreepool.com

 

[Rancho Cost-a-Lotta]

I don't see an FC level posted, but make sure you maintain FC levels high enough to avoid falling below minimum levels. FC/CYA Levels

 

[Rancho Cost-a-Lotta]

I didn't specifically mention it, but our recommendation is to drain as much water as you can and refill. It it will be much easier to maintain.

 

[Rancho Cost-a-Lotta]

As mentioned earlier (and by a fellow Arizonian),

Sorry, I rechecked your location...

 

[proavia]

@proavia Thanks! We have a whole house water softener, but it's not plumbed into our autofill and would be majorly cost prohibitive to do so. Instead we plan on installing a rain water collection system and using that to fill when available. The CYA is updated. It's at 30.

A backflow preventer, some PVC pipe and a bit of creativity would do it if run underground.

Mine was pretty easy as my garage, where the water softener is, is on the same side of the house as my pool. Neighbor wasn't quite as lucky - so he ran PEX from the softener in the garage, thru the attic and switched to PVC where the PEX exited the attic at the eave, ran PVC down the wall and donnected to existing autofill plumbing.

Another option is a dedicated water softener near the pool.

 

[julesbravo]

Thanks for all the help. I'll drain it as much as I can and start a refill. I think my existing water softener isn't going to work based on it's location without being overly cost prohibitive. We're already redoing all the gutters on our house this summer so adding rain water collection will be easy with that and I can put the barrel really close to the pool on my deck. Doing a dedicated one near the pool may work, but I'd have to build some sort of enclosure around it to hook into our dedicated fill line. I've ordered a salt test kit and I'll see what I end up with after refilling. I think I'll need to add some stabilizer to get the CYA up to good levels for SWG.

 

[Rancho Cost-a-Lotta]

Best of luck. Let us know how it works out. Retest the CH of your fill water. 400 ppm seems quite excessive but not out of the realm of possibility.

 

[julesbravo]

Will do. Even my water company FAQ on their website lists typical water hardness at 20gpg which would be 342ppm.

 

[Rancho Cost-a-Lotta]

Check TA while you're at it. It's a good number to know.