Should I raise CH?

[bligh]

Good Morning

After reading through applicable materiel I'm still not sure what is the best course of action.
My readings this morning
FC 5
TC .5
PH 7.4
CH 50
TA 125
Salt 3200
Temp 88

The PH has been 7.4/7.6 all year without adding MA .. surprised me.

After an initial bout of cloudy/tint of green water in May, the pool has been trouble free all year. The water quality has been crystal clear.

Thanks

 

[PoolStored]

Raise your CH to 200. From your heater manual:

 

[JamesW]

I don't really understand why the heater manufacturers think that calcium levels do anything to protect the heater.

The heat exchanger is copper, how is calcium relevant?

 

[bligh]

Thanks for your replies....
This was the quandary I found myself in this morning ..
perhaps, when in doubt do nothing applies?

 

[Getitrite]

Thanks for your replies....
This was the quandary I found myself in this morning ..
perhaps, when in doubt do nothing applies?

perhaps, when in doubt do nothing applies?

Unless - - - it's the "A" word - - -

 

[JamesW]

In my opinion, calcium is not going to help the heater.

If anything, it risks scaling.

However, the manufacturer might void the warranty if they get a warranty claim and they decide that the lack of calcium was to blame.

The manufacturer will go by their policy and they will not care what anyone else thinks.

In my opinion, there is not a clear choice that can be made on solid evidence and science.

In any case, only you can decide what is the best choice for you.

It is your choice based on your own research.

 

[PoolStored]

I was part way through typing the same sentiment. Well said.

 

[mgtfp]

I think there is a widespread belief that a thin layer of scale protects metal from corrosion. And it probably does buy one some time to provide protection in case of pH crashes. The appropriate way would be to prevent pH crashes in the first place.

That's where the manufacturer's advice is quite conflicting. On one hand they want calcite saturated water for protection, but they also warn of scaling which is actually exactly what they think is necessary to prevent metal corrosion. I don't understand how you are supposed to encourage the building if a small layer of scale and then stop it from growing.

I suppose if you plot corrosion occurrence vs CSI, you will see a correlation. But this would mainly be because pH is a massive contributor to CSI, and you would see that correlation already by plotting corrosion occurrence vs pH, which I believe is a much more important parameter when it gets to metal corrosion.

Unfortunately, there is a lot of literature out there using Calcite Saturation as an indicator for metal corrosion, so I guess the chances winning a case against a heater manufacturer would be slim. They will easily find an expert supporting their side, and will slash any advice from random people on the internet.

As said before, only you can decide for yourself based on your research.

 

[JamesW]

The primary protective layer is Copper (I) Oxide or Copper (II) Oxide.

Low pH dissolves this layer and exposes the elemental copper to oxidation.

It is possible that a very thin layer of calcium carbonate might provide some protection, but trying to form a thin layer without causing excessive scaling is difficult because the layer tends to provide a location that attracts more scale.

http://www.fwr.org/copper.pdf

 

[bligh]

Thanks everyone for your thoughtful replies.

The heater has been a bright spot this year, fired right-up and ran flawlessly all summer. I do keep it covered when not in use otherwise rain causes a CE error code...every time.

The other thing is PH which has been 7.4 to 7.6 all summer without MA?

All in all been a great year by the pool.

SWCG changed everything as did TFP.

Thanks

 

[mgtfp]

The other thing is PH which has been 7.4 to 7.6 all summer without MA?

That is indeed unusual, but I'd just be happy about it. As TA keeps rising over time with fill water additions, that lucky streak might eventually end. Time will tell.

 

[bligh]

That is indeed unusual, but I'd just be happy about it. As TA keeps rising over time with fill water additions, that lucky streak might eventually end. Time will tell.

This started last year, prior to this it was a steady creep upwards. Not complaining just seemed a little unusual. The pool is nearly 50yrs old...perhaps just showing her age?

 

[mgtfp]

Did anything change in your pool maintenance?

Have you been adding baking soda in the past? Even though TA is still at a level now where I would expect pH to keep rising.

Did you replace the SWG cell? Once a cell's ruthenium coating gets worn out, and generation of chlorine gas is not as strongly favoured against other electrolysis paths anymore, the pH rise by hydroxide generation may not be fully compensated anymore by the acidic processes of chlorine gas dissolving as HOCl into the water and the eventual reduction of HOCl into Cl- when it's "used up".

Have you replaced the vinyl liner? I don't really see how that would affect pH anyway, but still curious, 50 years is a good runtime. My pool is about 40 now on first plaster.

 

[bligh]

Did anything change in your pool maintenance?

Have you been adding baking soda in the past? Even though TA is still at a level now where I would expect pH to keep rising.

Did you replace the SWG cell? Once a cell's ruthenium coating gets worn out, and generation of chlorine gas is not as strongly favoured against other electrolysis paths anymore, the pH rise by hydroxide generation may not be fully compensated anymore by the acidic processes of chlorine gas dissolving as HOCl into the water and the eventual reduction of HOCl into Cl- when it's "used up".

Have you replaced the vinyl liner? I don't really see how that would affect pH anyway, but still curious, 50 years is a good runtime. My pool is about 40 now on first plaster.

Hi ... Pool maintenance has remained pretty constant, used borax once or twice this year. Same SWCG (my first) last four years, inspection end of last year looked new inside. I did replace the liner 4 years ago.

I've repaired the pool 2-3 times in the past, horizontal support along the bottom failed as well as a vertical support failed.

But the kids and gkids just love the pool!

Did test the ph this morning 7.6 steady as rain.

Thanks