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Hard water from the start

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Hello everyone,

My issue is that I have a base calcium reading of about 500 - 700 to start on my tap water (good ph from the hose - though my initial startup process always pushes that up and then I correct) - I am looking at ways to build a healthy startup process that includes reducing this calcium. Background: we have always purchased/rehabbed old hot tubs and not worried about the buildup/wear as it was a figured expense in comparison to purchasing a new tub to replace small parts. However, we finally just want a new tub and now I have to address the baseline problem with my water... looked into delivery for water.. nobody services our area. I've read about different options with soda ash, sodium hydroxide, etc... but like a clear and solid plan rather than making a guess and test method for new equipment. Any advice? .... it's appreciated. 

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Mainly because every spa manufacturer I know of will void your warranty if you fill with softened water. It is also standard wisdom in the pool biz. This could have originated from plaster pools, which will be eaten, literally, by soft water. I couldn't say, but wouldn't put any of my customers, or my spa, at risk to find out.

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On 4/13/2021 at 10:30 AM, RDspaguy said:

This could have originated from plaster pools, which will be eaten, literally, by soft water.

It did. Calcium saturation index is not applicable to any surface except plaster. Unlke plaster, FIberglass, VInyl, and Acrylic are not reactive to calcium. It has nothing to do with corrosion of metal parts of pumps, pH does however.

 The main reason not to have very soft water in a tub is to help prevent foaming caused from saponaceous substances in the water and from much empirical evidence that seems to be around 120 ppm or higher.

There is some very limited evidence that higher CH (250 to 400 ppm) might help prevent or slow cobalt spotting in the gelcoat of fiberglass pools and might also help minimize iron staining but nothing concrete has been determined one way or the other and it might just be an unsubstantiated manufacturer's claim. Spas are made from acrylic shells with a fiberglass reinforcement on the backing so this does not apply. There are a few fiberglass gelcoat spas made by some fiberglass pool manufacturers but these are not stand alone spas and are usually installed along with a fiberglass pool. There are also plaster spas that are built along with plaster pools. These can also be installed or built without a pool. However, as I stated, these are not the self contained, stand alone spas that most people have.

FWIW, I fill my fiberglass pool and attached spillover acrylic spa shell with softened water because the faucet by my pool goes through my water softener since it also feeds my outside shower and then adjust my CH upward to around 250 ppm. I have found that the higher CH does help prevent iron staining in my fiberglass pool Before I started doing this I had to treat the stains yearly with ascorbic acid to keep them under control. Since I have been bumping up the CH I have not had a stain problem at all.

There is nothing wrong with filling with softened water as long as you immediately adjust the CH upward if it is warranted. If you are filling a vinyl pool  there is no reason. If you are filling gelcoated fiberglass pool or spa it might be a good ides if you are having a staining problem. IF you are filling a plaster pool or spa it is necessary.

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On 4/13/2021 at 11:16 AM, d.sebens said:

I would think if you raise hardness that wouldn’t be an issue?

@waterbear care to comment?  I only ask because I filled mine with soft water and adjusted hardness to 200 ish. 

Those are my feeling and it's what I do.

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