Heat storage tank pH management

zxcv_1984 · July 9

Hello all,

I have a 1250 L water tank that I use to both collect heat from the solar collectors on my roof, and distribute the heat through radiation floors.
I somehow made a mistake managing the pH with sodium bicarbonate. pH now stands at around 9,4. Ideal pH would be between 8,2 and 8,4 (per manufacturer's recommendations).

I started adding fresh water (pH a bit below 7) 20L at a time, hoping to lower the total alkalinity until the pH starts moving down again. I've added around 60L up to now, and the pH has yet to move.

Are there other, better means than moving incrementally as I do to get the pH back where it should be?

I've read that for pools I could use muriatic acid or sodium bisulfate, however I'm concerned with their effect on copper.

Thanks for sharing you insights!

hot_rod · July 9

is it plain water ?

Pool supply places have ph up or ph down chemicals

Jamie Hall · July 9

Sodium bicarbonate is a very effective buffer— which is a fancy way of saying that you probably can't move the pH much with water. As @hot_rod said, you may be able to find a pool chemical to lower the pH. Otherwise, judiciously adding muriatic acid is probably the best — but do it slowly, and mix thoroughly after small addition. What will happen is that the pH will change slowly for a while — and then abruptly.

Larry Weingarten · July 9

Hi, Might vinegar do? It certainly would be safer to handle than muriatic acid. ☠️

Yours, Larry

DCContrarian · July 9

Have you measured the pH of your water? If your water is alkali that would explain both why your calculations are off and why diluting the mixture doesn't lower the pH much.

Jamie Hall · July 9

In some ways, you know, I think I would be inclined to say "oops. I goofed" and dump the whole tank, if I had somewhere to dump it. NOT a storm sewer. Or the lawn. Or the sanitary sewer. Or the septic system.

And start all over again.

And next time, don't do arithmetic. Add a small amount — and I do mean small — of your sodium bicarbonate, mix thoroughly, and check the pH. Sodium bicarbonate, as I noted before, is a strong buffer — and its ideal buffering range is around a pH of 9.5 to 10.0. Which means you are below its ideal range, and the pH will be very sensitive to concentration.

ethicalpaul · July 10

A sewer or septic can't handle 9.4 ph water? Even if you run fresh water down with it? Enlighten me please!

DCContrarian · July 10

Take a 1 liter sample of tank water, mix it with tap water until you get the desired pH. That will tell you how much you have to add to the tank to get the pH where you want it.

Jamie Hall · July 10

https://forum.heatinghelp.com/discussion/comment/1805889#Comment_1805889

True, high pH is a little less of a problem than low. And it depends so much on the volumes involved. Small amounts of high or low pH — few gallons — no problem. 1200 gallons into a 1000 gallon septic tank? Big problem.

ethicalpaul · July 10

1200 gallons of anything into a 1000 gallon septic tank seem problematic! The OP has 1200 Liters I think…still a large quantity but he shouldn't have to dump very much if he adds a gentle acid or some neutral water.

Heat storage tank pH management

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