Auto Fill with Extreemly Hard Well Water or Softened Water and SWG?

[mstgkillr]

I live in Cape Coral, Fl and have extremely hard well water. I have an oversized water softener and was considering using softened water for the auto top off. I listed the test results of my water below. Based on those results, what would you recommend? I'm not exactly sure how CH is added or removed from the pool... Does an in ground concrete pool with a Pebble Tec finish actually absorb CH?

It appears that if I use well water that I may end up with excessive CH and scale. If I use softened water I will have to add CH but I'm not sure how much or how often.

Well Water
Calcium Carbonate (CaCO3). I believe this is what you pool guys call CH but I'm not positive.
46 grains per gallon or 786.6 ppm

pH
7.41

Total Alkalinity
130

Softened Water
Calcium Carbonate (CaCO3).
<1 grain per gallon or <17.1 ppm

pH 7.85

Total Alkalinity
130

 

[Swampwoman]

Welcome!
What kind of pool surface do you have? Please add details to your signature.
If your softener has the capacity, that's what I'd use -- it's easier to add calcium than remove it But i have a vinyl pool so I don't need calcium at all.

 

[BoDarville]

The bigger concern from using well water would be any metals that may be present, in particular iron. I would test for that.

Based on what you have provided, I would go with the softened water. It is easier to add CH if it is needed as opposed to lowering it if it got too high. CH can be removed through Reverse Osmosis, assuming that service is available in your area. Although plaster pools (we classify Pebble Tec as plaster for purposes of CH) need some CH, I would rather have more control of when & how much is added and the softened water will allow that.

You can use Pool Math to determine how much CH you would need to add based on your test results and water volume of your pool.

 

[Patrick_B]

That is hard, a little harder than mine. It is CH (Calcium Hardness) it's just shown as CaCo3 on the test. No matter, that's what you have.

A few things to help answer you, need answering.. How big is this pool? How big is your softener? Most importantly, do you have a proper test kit to monitor this pool? If not, you really, really need one. With your CH, and TA you are at very high risk for scaling, especially if you let the pH get high. PT will not "absorb" CH, but CH can precipitate on it and cause scaling if that's what you mean. You will never have to buy and add CH, because it is going to be extremely difficult to keep the CH low enough as it is, based on the information above. I have to presume you have been filling the pool in the past with said well water? Let us know about the kit situation, but if you don't have one you should get one to monitor and protect the large investment you've made in that pool.

 

[chem geek]

Evaporation and refill will continually raise the CH level over time so you might consider using a pool cover to eliminate that problem.

 

[mstgkillr]

Welcome!
What kind of pool surface do you have? Please add details to your signature.
If your softener has the capacity, that's what I'd use -- it's easier to add calcium than remove it But i have a vinyl pool so I don't need calcium at all.

When the pool finally gets built, it will be plaster, probably Pebble Tec. I recently replaced the softener and I always oversize things so I should have the capacity. I'll double check when I get home.

The bigger concern from using well water would be any metals that may be present, in particular iron. I would test for that.

Based on what you have provided, I would go with the softened water. It is easier to add CH if it is needed as opposed to lowering it if it got too high. CH can be removed through Reverse Osmosis, assuming that service is available in your area. Although plaster pools (we classify Pebble Tec as plaster for purposes of CH) need some CH, I would rather have more control of when & how much is added and the softened water will allow that.

You can use Pool Math to determine how much CH you would need to add based on your test results and water volume of your pool.

Although I have never tested the iron content, I don't have any obvious signs but I probably should test it just to be on the safe side.

I understand that plaster pools require a certain CH but does CH reduce by other methods? I guess what I am asking, is if my auto fill has little to no CH, will I have to regularly add CH?

That is hard, a little harder than mine. It is CH (Calcium Hardness) it's just shown as CaCo3 on the test. No matter, that's what you have.

A few things to help answer you, need answering.. How big is this pool? How big is your softener? Most importantly, do you have a proper test kit to monitor this pool? If not, you really, really need one. With your CH, and TA you are at very high risk for scaling, especially if you let the pH get high. PT will not "absorb" CH, but CH can precipitate on it and cause scaling if that's what you mean. You will never have to buy and add CH, because it is going to be extremely difficult to keep the CH low enough as it is, based on the information above. I have to presume you have been filling the pool in the past with said well water? Let us know about the kit situation, but if you don't have one you should get one to monitor and protect the large investment you've made in that pool.

The pool hasn't been built yet but I do plan on buying a really good test kit. Any recommendations? I already have a professional grade CH kit and pH meters. The TA kit I borrowed from a friend. I assume if I use the softened water I won't have the issue of trying to remove the CH.

 

[Patrick_B]

It would be extremely rare to have a softener you could fill a pool with. At least in practicality. See if you can find out the grain capacity of your softener. Your kit, is it for the softener monitoring? It may be a Total Hardness Kit, but in any case, I suggest you buy a TF100 kit from TFTestkits.net. With speedstir option. If you have trustworthy pH meters and like them, you could alternatively order the TF50 from the same outfit. If it were me, I'd go with the 100 so you have backup pH test incase you get in a bind with meter issues. Find out about the softener, and I'll be glad to help figure this out.

 

[mstgkillr]

It would be extremely rare to have a softener you could fill a pool with. At least in practicality. See if you can find out the grain capacity of your softener. Your kit, is it for the softener monitoring? It may be a Total Hardness Kit, but in any case, I suggest you buy a TF100 kit from TFTestkits.net. With speedstir option. If you have trustworthy pH meters and like them, you could alternatively order the TF50 from the same outfit. If it were me, I'd go with the 100 so you have backup pH test incase you get in a bind with meter issues. Find out about the softener, and I'll be glad to help figure this out.

I definitely do not plan on initially filling the pool through the softener, just keeping it full with the auto fill. The grain capacity is 48,000 GPG so it should treat roughly 1,000 gallons before it needs to cycle. I have a 4/2 but only two people at the house. Yes, it is a total hardness kit but expressed in CaCO3 which I assume is CH. Total Hardness Test Kit, Model 5-B | Hach USA - Overview | Hach

 

[Patrick_B]

Yep that's a TH kit. Same one the softener guys usually carry. Great kit for that job. TH and and CH are both expressed as CaCo3 on all normal kits/methods. The different indicators and buffers determine whether its showing you TH (Mg & Calcium) or just CH. Since the CH test isolates the Calcium level only, the TH shows you both for Total Hardness. No matter, we can see from this that you likely have about 600 CH. TH is mostly Calcium, with a little Mg thrown in there...and the rest is a tiny smidge of everything else.

So, the end result is you won't be able to stay within normal guidelines for CH unless you can locate another water source. You can makeup with the soft water, and possibly use rain water for dilution. We have members who divert rain from their roofs to lower/dilute the pool water when they have high CH. I'm right there with you though, as my well is about 730 CH. You have to maintain pH control tightly, and working the TA down helps as well. It takes effort keeping a hard water pool in shape, but it can be done more easily than you might think.

 

[chem geek]

My rough rule-of-thumb for natural water is that CH is around 70% of Total Hardness (when both are expressed as ppm calcium carbonate) so around 550 ppm in your case, but that's just a rough estimate. This is based on a molar (or molecular/atomic) ratio of 4:1 calcium to magnesium being typical. It definitely varies, though, and in the San Francisco and peninsula (Hetch Hetchy water) system, the ratio is 2.6:1.

 

[Patrick_B]

Yes indeed, mine was a very rough estimation.

 

[mlbillow]

We filled and maintain our pool via a water softener. Although the water softener couldn't keep up while filling, it was able to cut down on the extremely hard water we have in San Antonio. Actually, I didn't have a proper test kit at first and went a while with CH at only 100. I have since boosted it up to 250 and might bump it up to 300. With as much evaporation we have in the summer, the CH levels would get high really quick so am glad we have the softener to fill as needed.

 

[Isaac-1]

I am going to go partly against what others are saying, you are in south florida, and likely get LOTS of rain in the form of afternoon thermal thunderstorms in the spring and summer. Rainwater is CH free, so I doubt your incidental fill water from the well is going to have a big effect on the CH in the pool. Metals may be another concern, in which case you might consider routing rain water from the house gutters to a sand filled barrel, then on into the pool to top off.


Ike

p.s. a google search shows Cape Coral averages just under 10 inches rain each month June - Sept with the dry season being Nov-January where the total for those 3 months is less than 10 inches (annual average total around 56 inches)

 

[mstgkillr]

I am going to go partly against what others are saying, you are in south florida, and likely get LOTS of rain in the form of afternoon thermal thunderstorms in the spring and summer. Rainwater is CH free, so I doubt your incidental fill water from the well is going to have a big effect on the CH in the pool. Metals may be another concern, in which case you might consider routing rain water from the house gutters to a sand filled barrel, then on into the pool to top off.


Ike

p.s. a google search shows Cape Coral averages just under 10 inches rain each month June - Sept with the dry season being Nov-January where the total for those 3 months is less than 10 inches (annual average total around 56 inches)

Yes, we usually get a lot of rain but wouldn't that make using softened water even more appealing? If a good amount of my top off comes from rain water, the auto top off would have an even lower demand on my water softener while still having the benefit of an almost zero TH. I guess what am I saying is, why risk using well water if I only need a small amount of top off water from the softener.

 

[Isaac-1]

My point was that with around 5 ft of rain per year the amount of CH added by the well should be minimal, however metals are another potential issue with well water which would not be removed by the softener.

 

[Swampwoman]

Actually the softener WILL reduce the amount of iron going in to a more manageable level if there's iron in the well water. It will also remove some maganese and much of that lovely sulphur some of us well-folks get

I say this because my well has all those lovelies...and if I were building new, not only would I oversize the softener capacity for auto fill...I'd also be adding an "iron curtain" treatment tank (oxidizes higher levels of iron than a softener can handles, eg. Source water over 2 ppm.)

The iron curtain tank is about 2k installed...but a lifetime of phosphonic and ascorbic acid can add up over the years

 

[Patrick_B]

Just note that when your softener does exchange for Iron, it shortens the resin life significantly. Resin does not hold up well in those circumstances, and you'll see a gradual to dramatic loss in softener performance.

 

[cheddar85]

My understanding is that it doesn't shorten resin life, rather reduces resin capacity over time. When the softener exchanges iron, and is then recharged, all the iron is not removed, so it gradually builds up in the resin bed. There are products you can add to the brinewell every so often to remove the remaining iron from the resin. Also, as far as I know, softeners will only remove ferrous (clear water) iron. Up until 3 years ago, we had an OLD Culligan water softener (Mark 49?) that was installed by my dad in 1983. The only reason we replaced it was because the timer assembly fell apart. Even on its last legs, it still softened to almost its rated capacity.

Incidentally, when we replaced the liner last year (only 3 years old, don't ask) I DID fill the pool entirely with soft water. It took a while and a lot of babysitting, but with an iron content ranging from 4-6 ppm it was the better way to go.

Btw, has anyone ever put 0 CH into Poolmath and looked at the CSI?

 

[chem geek]

Yes the CSI goes infinitely negative when either TA or CH become 0 since the logarithm of 0 is negative infinity. That does not imply anything about the rate, however. It just means there is no calcium or no carbonate in the water. The rate of plaster degradation is accelerated by low pH, but a zero CH doesn't instantly cause degradation. And of course if it's a vinyl pool and not plaster than this doesn't matter. It also has little to do with metal corrosion where again the pH is the dominant factor.

A CSI of -0.3 means that either calcium or carbonate or their product is half the amount at saturation, -0.6 means it's one-fourth, -0.9 means one-eighth, etc. So being near saturation slows down dissolving of plaster but there is a limit to its rate of degradation and that rate is more a function of pH than anything else where low pH dissolves the calcium carbonate in plaster faster.

 

[Patrick_B]

Sorry to not be more clear Cheddar, but to me it's saying the same thing. You'll have to replace the resin before you should once it's Iron fouled. In some (many actually) this can be much sooner depending on the resin, and of course Iron level.

chemgeek, I think it's something extremely important to know and remember that about the index. The Log factor regarding CSI is either not realized, or forgotten about. This happens with pH too, and it's critical information.