PH drop

chadm

Premium Member
Hi,

Ok, some quick background, 55gal SPS dom. tank - no refugium - no macro algae in tank except a nusiance dictoyta (sp)

Daytime PH is 8.3
4 hrs after lights out 7.9 with 7.7 before lights on.

I have my skimmer's air intake hooked directly to outside air supply.

What can cause such a massive PH drop within 4 hrs of the light turning off? I oringinaly thought it was indoor CO2 but after plumping straight to the outside it does not make a difference.

Best Regards

Chad
 

Randy Holmes-Farley

Reef Chemist
Premium Member
Low pH, assuming it is real and not a measurement problem, is ALWAYS due to excess CO2 if the alkalinity is normal to high. A pipe to a skimmer is not always adequate if the tank top is exposed to high CO2 air.

In your case, there just may not be enough aeration. That is a big pH swing that will disappear if there is perfect aeration with normal air.

Is the tank in a bedroom where you breath out a lot of CO2 at night?

This article has more:

Low pH: Causes and Cures
http://reefkeeping.com/issues/2004-09/rhf/index.htm
 

chadm

Premium Member
The tank is in the living room. I just don't know how I can get more fresh air into this tank..

driving me bonkers :D
 

Randy Holmes-Farley

Reef Chemist
Premium Member
Try the aeration experiment in the room in the AM and the PM and see what happens.

Adding more limewater may be the best option, perhaps by using fans or adding milky limewater.
 
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