does running carbon raise your pH

[sillygoose]

We had this situation out on a job site where a carbon/coconut filter was used to remove diesel odor from a water sample. It did a great job removing volatile organics but now the pH is quite high - bouncing from 9-12 from neutral. I did a bit of investigating and this may have occurred because the carbon was not properly wetted before it was put into use. I suggested they leave the filter stay wet for a day before trying again. I hope to have some new data tomorrow morning.

So my question is, has anyone noticed this phenomenon with running carbon? Do you get an initial pH spike and could you actually use this to bump pH up when it is too low?

 

[2006]

Check out this post in the chemistry forum:

http://reefcentral.com/forums/showthread.php?t=1231262

Sounds like carbon can have a high pH if it is not acid washed to remove the ash.

 

[99Trev]

Was the carbon "activated"? The carbon "bag" that I get from the pet store is activated carbon, and I have always just rinsed it, and put it in the canister (that is what the directions say on the package). I remember reading somewhere about non-activated (or natural) carbon, and it had to go through a reactor or something like that to make it safe for the aquarium. I might be way off in my thinking though (or confused with something else, and both are very possible).

I have never monitored my PH levels when doing the carbon change. I might give it a try when I do my canister maintenance.

 

[sillygoose]

I will check out that link 2006.

Trev, I have also read that activated or oxidized carbon will not have the pH effect, but out on our job it seemed to. Of course the coconut in the filter would certainly have something to do with it too.