PH decrease in holding tank

[steve s]

Trying to set up holding tank. PH out of tap 7.4. If leave
water out for 24 hours PH goes down6.5-6.7 Most people
say the PH goes up after you let sit.
Can the PH go down instead of up after water sits 24 hours ?
I have soft water 1-3 out of the tap.

Hi Steve S

You may want to post this in the Water section.

You have said it right. The pH can decrease if ther is little buffering in the water. (KH).
When you say you have 1-3 are you refering to GH or KH ?
If it is KH (in german Degres) you could add back some KH with Backingsoda or you could place some crused coral in the Fishtank filter, that also stabalizes the water.
I have simelar water and had it sit for 48 hours with air with the result that it stabilized.

HTH Ronald

[Ryan]

Hi Steve,

Depending on your water chemistry, the pH may shift up or down after it aerates overnight. As Ronald mentioned, water with a low buffering capacity has a tendency to drop.

Ryan