Conflicting opinion: Filling pool with hard or soft water?

shacke

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Jul 5, 2010
134
Philadelphia
I took ownership of a pool when we moved in 3 summers ago and I am finally getting serious about learning the ropes.

When we moved in the sellers told us to bypass the whole house water softener when filling the pool. They said the pool builder told them the soft water would leech minerals/etc from the paint and/or plaster and ultimately shorten it's life and finish. I mentioned this to a pool tech who opened my pool and he said that isn't true.

Certainly, off the cuff, I would think that softer water would be easier in terms of maintaining chemistry but I do not want to damage the paint or plaster.

Incidentally, I am having some scaling issues which is why I bring this up although my CH is 250. I have been trying to lower my TA as pH is hard to keep down with the SWG but that is another issue I am battling now and my sense as to why scaling is happening.

Thanks for a firm answer in advance. :-D

This morning.
FC 5.5
CC 1.0
CYA 40 (just added to hopefully get to about 50 today)
pH 7.5
TA 130
Temp 82
 

NWMNMom

TFP Expert
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Apr 8, 2007
1,582
Waaay NW MN
The reasons that soft water is better for your house and home is the same reason soft water is good for your pool.
 

Richard320

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Jan 6, 2010
20,941
San Dimas, CA (LA County)
Seems to me that adding some Calcium is a heckuva lot easier than getting rid of it. If I had a water softener, that's what I'd use to top off my pool! You can do the opposite - fill with soft, replenish with hard until CH gets near the limit, then switch back.
 

shacke

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Jul 5, 2010
134
Philadelphia
That's what I thought - thanks. Of all things, I do NOT want to replaster before I have to!

Much appreciated!

Evan
 

Bama Rambler

Mod Squad
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Jun 22, 2009
23,061
SouthWest Alabama
If you'll keep the levels near the recommended values and the CSI near to just below zero you won't harm your plaster or have scaling issues. The best thing is that the Pool Calc figures all this for you and all you have to do is maintain.
 

chem geek

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Mar 28, 2007
12,082
San Rafael, CA USA
It is odd that you are having scaling issues since your CSI is around +0.1 but if you are referring to scaling in the saltwater chlorine generator cell, then that makes sense and is why one often runs the CSI slightly negative. So yes, lowering your TA would help. You could also consider using 50 ppm Borates in your pool since that acts as an additional pH buffer that cuts the pH rise in the salt cell roughly in half so helps to prevent scaling.

The main reason to have the auto-fill go through the water softener is that evaporation and refill adds whatever is in the fill water to your pool since evaporation only removes water. So if most of your water addition from the auto-filler is due to evaporation, then using softened water makes sense so that you don't keep increasing CH over time. If most of your water addition is due to making up for water dilution from backwashing, carry-out, splash-out, then using the original water might be OK if the water isn't extraordinarily hard (i.e. with a CH higher than the water in the pool).
 

shacke

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Jul 5, 2010
134
Philadelphia
Hi Chemgeek

The scaling is actually on the pool walls. It is hard, white streaks almost like a bird dropping on the side of a car or dripping candlewax. I assume it because my pH tends to stay high (7.8) if not aggressively driven down. Recently it got to 8.0 and I wonder if that is what precipitated the new scaling - no pun intended. I went through the pool with a scrungie and goggles and got most off pretty easily although some of it is too hard to remove without my worrying about damaging the plaster.

I am hoping that by increasing my CYA level, and then reducing TA and adding borates, that the pH will stabilize.
 

chem geek

TFP Expert
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Mar 28, 2007
12,082
San Rafael, CA USA
Ah, that make's more sense, especially if the pH got closer to 8.0 since the CSI would approach +0.6 at that point. Yes, lowering your TA should help. The Borates should slow the rate of pH rise, but not the amount of acid you need to add unless you have nascent algae growth and are able to turn down the SWG on-time as a result.
 

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