PH down after adding live rock and sand

[BryanM]

For the couple weeks prior to the live rock and sand arriving, PH was steady at 8.3 (it was only salt water in the tank, otherwise bare).

It has dropped to 8.16 after I put the rock and sand in the tank. Is that normal? Or even anything to worry about?

Thanks!

 

[GARRIGA]

Are3 there more people or pets contributing to house co2?

 

[BryanM]

Are3 there more people or pets contributing to house co2?

Two people total, and two small dogs.

 

[UMALUM]

Your alk probably dropped.

 

[GARRIGA]

Two people total, and two small dogs.

Was that how it was before adding the rocks?

 

[BryanM]

Was that how it was before adding the rocks?

Yep. My wife, me, tank (8 pound chihuahua, and Leroy, 13 pound "unknown" mix)

 

[GARRIGA]

Yep. My wife, me, tank (8 pound chihuahua, and Leroy, 13 pound "unknown" mix)

Trying to exclude house co2 from the equation. Know of no reason why pH would otherwise drop from adding rocks or sand.

@Randy Holmes-Farley

Can you assist?

 

[UMALUM]

Wouldn't the addition of the rock and sand result in a cycle and swing the alk and ph?

 

[DanyL]

Live rock contains organic matter that will start decaying after introduction, releasing CO2 into the water, and therefore would lower the PH.
It’s completely normal.

 

[PharmrJohn]

Could the addition of bacteria (coming in on the live rock) increase pH via cellular respiration? Glucose+O2 ---> CO2+H20+energy (unbalanced equation)?

 

[Spare time]

What is the error margin of the pH test or meter you are using. Many have an error margin of 0.2

 

[DanyL]

Could the addition of bacteria (coming in on the live rock) increase pH via cellular respiration? Glucose+O2 ---> CO2+H20+energy (unbalanced equation)?

I’m not a chemist or a biologist, so I can’t answer this. Hopefully @Randy Holmes-Farley or @taricha can chime in and further explain the process.

What is the error margin of the pH test or meter you are using. Many have an error margin of 0.2

That’s a fair point, but considering that there is a known cause that does affect PH, I believe the reading, or at the very least the trend downwards was accurate.