Calcium hardness and salt rising, again

[JoyfulNoise]

Maybe @JoyfulNoise can enlighten us on the GAC pre-filter he has.

I use WaterTec for my softener. They are a local AZ company and completely in the water treatment business. It’s the entirety of their business so they know what they are doing.

I have their dual eliminator system. It looks like a single tank but it’s actually two tanks stacked vertically on top of one another. The upper tank at the distribution head is where the GAC is located. I forget how much GAC is in that tank but I’d say it’s a few pounds at least. The water hits the GAC first and it removes all the chlorine/chloramine/VOCs as well as iron and heavy metals. Then the water flows down into the resin tank where calcium and magnesium are removed. The treated water then exits up the center standpipe.

If you wanted to do a GAC prefilter on an existing system then it would have to be a separate filter from the softener. It would need to be sized correctly for plumbing pipe diameter as well as flow rate. My suggestion would be to do a setup, if you have the available space, where you do a sediment trap (spin polypropylene mesh) to remove suspended solids (dirt, silica, etc) and then a GAC filter to remove chlorine/chloramine, and then the softener. In that type of setup, you would be looking at changing the sediment and GAC filters either annually or every 18 months and then the resin would be changed every 10-15 years. Sediment and GAC media are cheap compared to cationic softener resins.

 

[proavia]

My neighbor uses this setup to pre-filter before the water softener.
He changes the filters out yearly, same time he does his RO filters.

Amazon.com

 

[mprzybylski]

My neighbor uses this setup to pre-filter before the water softener.
He changes the filters out yearly, same time he does his RO filters.

I have a similar setup, but one stage. i also change it out yearly.

 

[JoyfulNoise]

Carbon block is similar to GAC with the main difference being that CB is a solid porous material whereas GAC is granular and much higher surface area. There are also chemical properties associated with GAC that improve its ability to remove VOCs as well as heavy metals. I think GAC or CB would work in that application. The critical element is making sure the filters and plumbing at sized properly. If you make the system too small you’ll create a pressure drop that can make appliances freak out in the house … or a spouse complain about water pressure …

 

[mprzybylski]

I have a plumber coming out to look at the water softener tomorrow, but I was thinking about this a bit more over the weekend. In my original post I talked about the fast and high rise in CH and salt that I experienced last year, before plumbing the water softener to the auto fill and subsequently refilling the pool in November. This year, with the WS/autofill plumbed, it is still doing this but at a slower pace. Considering all of that, is it still the thought that it is my water softener as the issue, or is there possibly something else going on that I am not thinking about since it was also happening last year without that plumbed? Or, is the thought that its slower this year BECAUSE of the WS, but since the WS may not be working fully as it should, it's still happening?

I guess essentially what I'm trying to say is that if the WS is not working correctly, and it subsequently gets fixed to work as it should, I'm hoping that this actually solves my problem and there is nothing else at play here.

 

[JoyfulNoise]

There is no reason your salt should be rising at all unless you are adding chemicals with a lot of chloride in it. I live in roughly the same climate as you do, maybe a few degrees cooler down here in the summer (like 5 or less) and my salt levels never change.

Can you quantify the rough amount of salinity increase and the time period over which that occurred both before the WS was added and after?

How are you testing for salt levels?

 

[mprzybylski]

Can you quantify the rough amount of salinity increase and the time period over which that occurred both before the WS was added and after?

Pre-WS salt levels were 3600 at fill time on Sept 6 2021 and 4400 on Nov 6 2022 before I made my first post about this issue.

Post-WS salt levels were 3200 at refill on Nov 15 and today sit at 4000.

How are you testing for salt levels?

I'm using the K-1766 salt kit.

 

[JoyfulNoise]

Your biggest chemical contributor to salinity is going to be muriatic acid and any liquid chlorine you may have added to the pool during that time.

Can you quantify how much acid has been used to control the pH over those time periods?

 

[mprzybylski]

Can you quantify how much acid has been used to control the pH over those time periods?

I have added quite a bit of acid over time to control pH at it seems I'm constantly trying to keep my pH between 7.2-7.8 (which was the advice I received last year around this topic). On average I'm adding 24-30oz of acid every 3-4 days to keep pH levels at that mark.

I've only been adding very small amounts of liquid chlorine during the winter months (i may go through a gallon a year) when the SWG shuts off due to low temps and I see a bit is needed to get back up to ideal FC levels.

 

[JoyfulNoise]

So I was doing some "back of the envelope" calculations for your pool and you would need to add about 2.3 gallons of acid per month to see the chloride ion concentration go up by as much as you have. If I use your addition numbers on the higher end of the ranges you provided, I can get close to 2.3 gallons per month. So your salinity increase is coming mainly from your acid additions.

I'm not sure I would have advised you to lower the pH all the way down to 7.2 as that is unnaturally low for our climate and water conditions. If pH rise is an issue, then the recipe is to try to get the TA below 80ppm (mine typically sites around 70ppm and my acid additions will usually drop it to 60ppm each time I add) and then you want to maintain the water's pH between 7.6 and 7.9. You'd only add acid once you're seeing the pH at the upper end of the scale and then only add enough acid to drop the pH to 7.6. There is no benefit to going to 7.2. When I follow that protocol, and given the fact that I have borates in my pool water, I can usually go about 10-14days between acid additions.

So your chloride ion increase is reasonable given how much acid you have been adding to your pool. Your water softener is probably undersized for the task of supplying soft water for people use and pool use and so you are probably exhausting the resin before it regenerates and so you are still adding calcium laden water to the pool. Given the age of the resin and the fact that is sees no pretreatment to remove chlorine from the municipal supply, I suspect your softener resin is probably degraded and no longer able to supply the capacity it was rated for when it was new.

At the very least, if you still have the plumber come out, I'd suggest talking about upgrading the softener to a larger model and adding in some sediment and chlorine removal pre-treatment as well. Once you regain consciousness after seeing the plumber's quote, you can decide if it's worth it to you.

 

[mprzybylski]

I'm not sure I would have advised you to lower the pH all the way down to 7.2 as that is unnaturally low for our climate and water conditions. If pH rise is an issue, then the recipe is to try to get the TA below 80ppm (mine typically sites around 70ppm and my acid additions will usually drop it to 60ppm each time I add) and then you want to maintain the water's pH between 7.6 and 7.9. You'd only add acid once you're seeing the pH at the upper end of the scale and then only add enough acid to drop the pH to 7.6. There is no benefit to going to 7.2. When I follow that protocol, and given the fact that I have borates in my pool water, I can usually go about 10-14days between acid additions.

I'll try this approach moving forward because clearly what I was doing before isn't working. My TA is at 70 currently so I'll start to manage pH at 7.6-7.9 levels (how do you gauge 7.9? the test goes from 7.8 to 8, so are you just kind of assuming what 7.9 would look like based on the other colors?) and see how it goes.

Borates are interesting, do I need to look more into it? I'd love to stop having to add MA every 3-4 days and level off my pH a bit. I was told and read on here that pH should level out after the first year, but in my case that does not really seem to be happening and I'm constantly fighting it from going too high.

So your chloride ion increase is reasonable given how much acid you have been adding to your pool. Your water softener is probably undersized for the task of supplying soft water for people use and pool use and so you are probably exhausting the resin before it regenerates and so you are still adding calcium laden water to the pool. Given the age of the resin and the fact that is sees no pretreatment to remove chlorine from the municipal supply, I suspect your softener resin is probably degraded and no longer able to supply the capacity it was rated for when it was new.

This makes a lot of sense. The WS was installed when we first moved in, long before we had a pool and we plumbed the WS to the autofill. Considering the age of the WS, I may as well just look at a replacement thats sized more appropriately for our now use with the pool and having a better idea of how we use water in the house considering we've lived here for almost 7 years.

The plumber is a neighbor of mine, and I've helped him in the past a few times on some woodworking things he's had come up, so he gives me a relatively good deal on water issues (he plumbed the WS to my autofill for free last year), but I don't doubt this one will be a bit more expensive . Hopefully it does not completely break the bank because I'd love to get this figured out as it is a constant source of stress for me. I'd like to get everything dialed in to ideal levels and not have to worry about it so much.

 

[JoyfulNoise]

7.9 is really easy to read off a pH meter … it’s right after 7.8 but before 8.0

I’m also fairly skilled in my phenol red readings having spent most of my adult life in a chemistry lab engineering some fairly complicated processes.

As for borates, you can read about them here - Borates in pool - Further Reading

 

[mprzybylski]

lol, well the TF-100 test kit for pH doesn't have a 7.9, 7.8 straight to 8.0, so I have guessed at that number before as well, but I'm not as skilled at reading reds

Thanks for the link on borates, it looks like a fair amount of work to get going with it (and money investment), so I think the best route for me at the moment is to get my WS issues fixed up and see where that takes me. If I feel like I still need to do something about the pH after that, maybe I look into borates once again. I don't want to introduce too many variables all at once.