pH Crash: Cold Tap Water vs. Hot Tap Water

[Roan Art]

I set up my new 75g and because it was just full of flourite, I filled it with pretty much all cold water from my cold water tap. A day later, I emptied 3/4 of it out, planted my plants and filled it with just below room temperature water -- which is the temperature of the water the plants had been sitting in for a couple of days. It would have been around 68*-69*.

A day later, today, the pH crashed. WTF?

I tested my tap water:

pH 6.6
dKH 1
dGH 4

WHAT? Three days ago it the pH was 7.4!

On a hunch, I tested my hot water -- after I let it cool down:
pH 7.4
dKH 2
dGH 5

So, I would assume that my hot water is being influenced by something -- probably calcium or lime deposits -- in the water heater, would that be correct?

Now, people are told to take a cup of tap water, let it sit all night and then test it in the morning, but is that for cold or hot tap water? Does it matter? If I let this cold water sit overnight, will it most likely rise in pH?

I'm going to try that, but I thought I would ask someone here while I experiment.

Roan

 

[aquarob]

Roan, thats exactly what it is. The PH of your hot water *will* usually vary from your cold, unless you have a brand new water heater/lines. They generally use copper lines for hot water in most older homes, and all kinds of metal deposits build up both in the lines and in the water heater.

You can help alleviate this problem by draining a gallon of water from your hot water heater first thing in the morning, before using any hot water for the day. Generally, its a good idea to do this once every 6 months of so, to remove a lot of the sediment from your hot water heater. It has the added benefit of extending the life of your water heater and helping to maintain a more stable PH between your hot and cold water lines. Hope that helps. Take care.

P.S. Roan, thanks for tipping me off about Tanner, good man. =P

 

[Roan Art]

Roan, thats exactly what it is. The PH of your hot water *will* usually vary from your cold, unless you have a brand new water heater/lines. They generally use copper lines for hot water in most older homes, and all kinds of metal deposits build up both in the lines and in the water heater.

We upgraded the water heater to 80 gallons when we moved in in 2000. So it's only five years old. The house was build in '85, I believe.

You can help alleviate this problem by draining a gallon of water from your hot water heater first thing in the morning, before using any hot water for the day. Generally, its a good idea to do this once every 6 months of so, to remove a lot of the sediment from your hot water heater. It has the added benefit of extending the life of your water heater and helping to maintain a more stable PH between your hot and cold water lines.

Yah, I was aware that it was supposed to be drained at least yearly. We were told that when it was installed. Sounds like hubby hasn't been doing it I'll get after him about it, in the meantime I'll just make sure I use a decent mix of hot and cold water to fill any tanks.

P.S. Roan, thanks for tipping me off about Tanner, good man. =P

You're welcome

Roan

 

[carpediem]

There will still be a difference, even if you do your yearly HW heater maintenance. I believe that hot water will dissolve and pick up more solids in the lines than cold water. You can't flush your copper water lines and sink fixtures...