Ph Question

[mr troph]

:) Just a quick question. Is ph alterd by temperature?
Thanks.

Todd

[fishgeek]

no
unless you are boiling out limescale and reducing alkalinity... :shock:

[Professor_J]

In practical terms (for what we all do here) it will not do too much to your pH (I'm assuming you're talking about temperature changes of +/- 1-2°C and not 10-20°C) :).

However, temperature going up will decrease the solubility of CO2 (pour soda into an ice cold glass and a hot out of the dish washer glass, which one fizzes more?). Less CO2 means less carbonic acid, which means pH should go up. This (for many crazy reasons) is actually a very slow process unless you're boiling and making fish soup.

Temperature changes will also shift the numerous chemical equilibria in the water around slightly, but again, the temperature change required to shift these around enough to significantly change your pH would do more harm than the actual pH change.

Cheers,

J

[mr troph]

:) Thanks J.
The reason I was asking was I would like to get a acurate reading on Ph of my rain water tank which is very cool atm as its winter. I hav'nt any Discus yet I'm trying to work out a mix of rain and tap water that will satisfy Discus.
So should I heat my water in wc drum before testing.
Thanks

Todd

[Professor_J]

What I'd do (others will probably have other opinions) :) is check a few blends of tap and rain water to get a hardness that you want and the pH should follow. Also have them mixed and sitting at about the temp you're going to have your tank at rather than your outside temp.

Right now I'm getting ready to go with a blend of tap and RO/DI water that gives a GH on the order of 100ppm and a KH a bit lower (about 80). The pH on this is rock solid at 7.5. I can try to drop it with a pH down, but over a couple days it tends to come back up.

Some locals here apparently keep perfectly happy discus in our tap water which is 230+ ppm GH and stabilizes around pH 7.8-8.0. I'm just going to be spoiling mine a bit with the softer water. I'd guess that stable conditions that the fish can get used to are more important than fussing constantly with the water to try and get ideal conditions.

Oh and your fish will probably thank you if you preheat the water and don't throw cold outside water at them during your water changes.