reefbuffer oddity

[mids1999]

Added my pinpoint pH monitor to the reef today. :D

Noticed something very odd when I added reefbuffer to boost alk.
The pH went down about .05 from 8.13 to 8.08. confused:

Whats the deal with that? Shouldn't the pH have gone up?
The alk went up from 7 to 9.

[aquaman67]

The pH should rebound.

[mids1999]

pH is still at 8.08 and did not rebound back up.
Alk is still 9.
Any ideas about what happened?

[bertoni]

When baking soda is added to a tank, the pH usually drops due to the generation of CO2. Many of the buffer products act the same way; I think they have a lot of baking soda in them. So as the CO2 gasses off, over a period of hours, the pH might rebound, but a variation of that size could be due to a lot of reasons. I'd ignore it, myself.

[mids1999]

Ok well it seems as the lights went on tonight the pH slowly rebounded to 8.11.

Is this small change stressful to fish or corals? (0.05 point)

What is the typical daily pH bounce for a 75 gal system?

[aquaman67]

The pH has normal daily swings. In the morning it will be lowest.

When the lights come on photosynthesis starts to use up CO2. CO2 is acidic and drops pH.

As the level of CO2 drops, the pH increases until it reaches it's highest right before lights out.

A .05 swing is nothing.

Most systems swing .2 or more.

Mine goes from 8.0 to 8.3 everyday.

[mids1999]

Would it be a good idea to hook up an air pump to the controllers low range control to drive some of this co2 out of the water at night when pH drops like I do in my planted fw tanks?

[boxfishpooalot]

See my graphs I made to understand alkalinity and what makes its ph.This is the realative contribution in natural seawater(what we are aiming for)
<img src="http://i5.photobucket.com/albums/y178/salwaterfish123/alkph8.bmp" alt="Image hosted by Photobucket.com">
<img src="http://i5.photobucket.com/albums/y178/salwaterfish123/totalalkalinity.bmp" alt="Image hosted by Photobucket.com">

Also check out my little video on the alk and ph http://www.putfile.com/media.php?n=ph269 (quicktime needed)

Also its a great idea to keep bubbling outside air into your tank to raise ph.

[bertoni]

I wouldn't bubble air into the tank except with a protein skimmer, since it'll make a mess in most setups. I would just ignore the pH swings. If you want, though, you could add a refugium that's on a reverse light cycle to help with the CO2. That's a fairly common approach.

[mids1999]

How big a fuge would be needed to kwep tank ph level? (75 gal tank & 5 gal in sump)

[bertoni]

I really don't know. I guess I'd try to get a 20-30g refugium, if possible, and then light it well.