Water PH

Steve Paul

I was checking my fish tank's PH today, and it is 6.8. I deceided to check the tap water to make a comparison. The cold water checked out at 6.8 but the hot water was 7.2.
I make hot water in an Amtrol hot water maker, about 15 years old. I cleaned the heat exchange coil 2 weeks ago with Phosphoric acid (liquid ice maker coil cleaner). The reason I checked the hot water PH was to see if any residual acid was left in the tank. The suprise was that the hot water is LESS acidic than the cold water. WHAT'S UP WITH THAT???
Can anyone tell me why the hot water would be more alkaline (harder) than the cold. My presumtion was, that if anything, the hot water should be the same or slightly more acidic.
By the way, the Phosphoric acid treatment worked like a charm, the recovery is as good as new. And a little Baking Soda regulated the fish tank water PH.

Mark Eatherton1

Beats the flux outa me....

but my guess is that it has something to do with the use of typical soldering fluxes. Hot water can remove more flux than will cold water.

Got softner on line?

How old is the system?

What method are you using to test pH?

ME

Steve Paul

Hot Water PH

Got softner on line?
NO

How old is the system?
The house is 39 years old. The original copper tubing was soldered with 50/50. The present hot water maker is about 15 years old. The soldering was done with SilverBrite un leaded solder with some kind of generic flux (who can remember?)

What method are you using to test pH?
A Fish tank testing kit with a liquid testing solution - 3 drops added to 1/2 ounce of water, then compared to a color chart.

This all started when I was testing the tank and it came up reading 6.8. I wanted to check that against the source, the tap water, it was the same. While I was at the sink I tested the hot and it came up 7.2. I tested elswhere in the house and had the same results.

This kind of a cunundrum gets my Nit-Picking brain in a Tizzy. Why the differential?

Mark Eatherton1

Thats one of them thangs that'll make you go...

HMMMmmm. I'm going to defer to someone with a greater education in water quality control.

You would think that the flux would be long gone, but I've been back on jobs that were running potable water at and above 180 degrees for many years, and the flux was STILL on the inside of the pipe and fittings. My thought was that this could be influencing your results, but now that I think about it, that goes counterintuitive to my way of thinking.

In your case, maybe you're picking up residual hardness being drawn out of the water by the heating process. Hardness, as you already well know, comes out of solution where there is extreme heat and or cold. It concentrates it.

ME

Scott Denny

Temperature and pH Measurement

I did a google search and found one reference that said, "pH can indeed vary with temperature. The reasons why
depend on the context, but even a simple solution of a weak
acid (HA) will exhibit a (weak) temperature dependence".
Perhaps you could call a water heater manufacturer and ask tech support your question.

Marty_3

Ph and hot water

Hot water undergoes some sort of chemical change in the heating process where it loses some of its acidity- I don't understand the chemistry of it (depletion of oxygen?)Anyway, I've been observing for more than 20 years that the cold water plumbing on a well system will pinhole after years of service on low Ph and although the hot piping will thin out some, it's always far less than the cold piping.