Soft Water and Boric Acid

vegas-doug · Apr 25, 2024

I have few questions.

I am currently planning to re-plumb my auto-fill from a hard water irrigation line to the soft water loop on my house. I use potassium pellets for the soft water, even though they cost a bunch more. Is there any negatives with soft water in a pool, besides ensuring that the CH stays above 250?

I was getting scaling on my salt cell last year and have calcium on my pool tiles. Will soft water eliminate the salt cell issues? Last fall I purchased some boric acid based on recommendation in this forum and what I read online to help prevent salt cell buildup. I also have an infinity edge spa so I get calcium around that. I have not put the boric acid in yet but are there any negatives with using borates besides having to stop drinking pool water?

Thank you!

mknauss · Apr 25, 2024

Using softened water will reduce the CH build up. But not reduce your current CH levels. What is your current CH level?

You can use the boric acid. It will reduce the pH rise in the SWCG cell that causes the scaling in it. No downsides. Be sure the boric acid level you add is input into PoolMath as it effects the acid addition levels for pH control.

duraleigh · Apr 25, 2024

The softened water you use for refill should help with ALL your scaling issues.

I am personally dubious of the benefits of borax.......there just doesn't seem to be enough evidence to suggest it is really beneficial.....although I also think it is harmless.

vegas-doug · Apr 25, 2024

mknauss said:
Using softened water will reduce the CH build up. But not reduce your current CH levels. What is your current CH level?

You can use the boric acid. It will reduce the pH rise in the SWCG cell that causes the scaling in it. No downsides. Be sure the boric acid level you add is input into PoolMath as it effects the acid addition levels for pH control.

Currently around 550. Just drained enough water to bring it down from around 800.

Will it use more or less acid? I have a stenner injection pump that injects little bit of acid every morning to keep my ph between 7.4 and 7.6.

vegas-doug · Apr 25, 2024

duraleigh said:
The softened water you use for refill should help with ALL your scaling issues.

I am personally dubious of the benefits of borax.......there just doesn't seem to be enough evidence to suggest it is really beneficial.....although I also think it is harmless.

thank you. guess I will give it a try since I already bought it.

vegas-doug · Apr 25, 2024

mknauss said:
Using softened water will reduce the CH build up. But not reduce your current CH levels. What is your current CH level?

You can use the boric acid. It will reduce the pH rise in the SWCG cell that causes the scaling in it. No downsides. Be sure the boric acid level you add is input into PoolMath as it effects the acid addition levels for pH control.

I forgot to ask about best level of borates. I've seen 30-50 ppm is recommended by many, but once source I found said that it should be 70 ppm if using salt cell. What level does TFP recommend?

mknauss · Apr 25, 2024

Borates in pool - Further Reading

www.troublefreepool.com

You end up using the same volume of acid over time. Not sure how a dosing pump for acid will work as normally the borates allow you to go longer between acid additions, just more acid each time.

ManiacalMama · Apr 27, 2024

vegas-doug said:
I forgot to ask about best level of borates. I've seen 30-50 ppm is recommended by many, but once source I found said that it should be 70 ppm if using salt cell. What level does TFP recommend?

My borates are about 35ish. I was aiming for 40 but didn't quite get there and the 35 is enough to stop the SWG scaling for me so I called it good. My acid additions are about every 5 or 6 days vs. every 2 without.

Dirk · Apr 27, 2024

vegas-doug said:
I was getting scaling on my salt cell last year and have calcium on my pool tiles.

When I bought this house, the pool finish and tile were covered in scale. I had to replace the finish and have the tile blasted. Since getting my CH to about 350, and then using soft water to replace evaporation, the scaling on my pool finish has never reformed. I only check my SWG plates once a year now, and have yet to find any scale there. For several years of very diligent attention to my CSI, keeping it very close to -0.3, my tile was looking great. I thought I had solved for that, too. But it eventually started collecting some scale:

No where near as bad as it was, but not pristine. Maintaining CSI definitely slowed down the accumulation. I think what is happening is now unavoidable. It's not a water chemistry issue, because my chemistry is always near-perfect. I think the water splashes up on the tile (wavelets from wind, mostly), and then evaporates. The evaporation leaves some minerals behind.

The mistake I have made is not maintaining it better, even though I knew to, and reminded myself to, I just couldn't seem to get to it. I think if I had regularly gotten in the pool and scrubbed it off, I wouldn't now be staring at this bigger chore. So I will do whatever is necessary to restore the tile, and then be more diligent in keeping it that way. But the finish and SWG are taking care of themselves.

I also have automated acid injection, which controls the high TA in my fill water, and I have started to replace water annually to maintain my CH. I let it get up to over 500, which took like five years, and then replaced a lot. But from now on I'm going to do smaller exchanges, once a year in the Spring, and keep the CH level more stable. I replaced the water with soft water, which is pretty much CH-zero, so I wouldn't have to exchange as much. I figured out what my softener is capable of: X number of gallons, then manually regenerate, then another X number of gallons, etc. Otherwise, if I used city water, which is full of CH where I live, it would require a much bigger exchange. As I was refilling the pool, I was periodically testing CH. When I stopped getting CH zero, I knew that the softener was tapped out, so I stopped the fill, set the softener to regenerate, then started the fill again.

Anywho, that's my MO.