View Full Version : pH Question???

03/07/2010, 04:14 PM
Hi Fellow Reefkeepers,
I'm trying to understand pH a little better. Today the pH in my 65 gal. reef tank tested at 8.8. It has always tested at 8.4 or 8.2 in the past 6 months. Here are my questions:
1. If my reef tank pH is 8.8, does that mean I need to "lower" the pH to 8.4 or 8.2? Is the term "lower" correct in this case?
2. What's the best way to bring my pH back to 8.4?
3. What do think made my pH change to 8.8? I just did a 7 gal. water change three days ago in my 6.5 gal reef tank...so I'm puzzled???

Thanks for any help you can give me!

:) Laurie

03/07/2010, 04:20 PM
What's been dosed into the system? Unless something like kalk has been added, the pH likely is much lower than 8.8. If the pH level is high, more aeration will bring it back in line.

03/07/2010, 04:29 PM
The only thing that I've dosed was two-part B-Ionic on 3/1. I have mostly soft and LPS corals and only one very small 2" high SPS frag. Could the B-Ionic have changed my pH?

I have a large Venturi protein skimmer, and an Eheim return pump. I have two Hydor Koralia powerheads that I run 6 hours a day. I run the return pump and protein skimmer 24/7. Seems like I have a lot of aeration, but do you think I have enough?

03/07/2010, 04:49 PM
I forgot to mention that I'm also running Black Diamond Carbon in my sump. I wonder if I'm running too much carbon? I'm using about 1/4 cup of carbon that I change every two weeks.

03/07/2010, 04:57 PM
you might bring in a sample of your water to your LFS and let them test it too to make sure your test kit is accurate.

03/07/2010, 05:51 PM
That's a good idea. I can do that - thanks!

03/07/2010, 06:42 PM
I was just reading on another forum that "the brighter your bulbs - the higher the pH". Today I tested after my MHs had been on for 5 hours. Now I'm wondering if this pH climb has to do with the metal halides! I'll re-test this evening when I turn on my PCs. Thanks everyone for helping me figure this out. I know pH is kind of tricky. I'll let you know the results of the pH test after I turn off the metal halides for a while.

03/07/2010, 06:48 PM
You did a 7 gallon water change on a 6.5 gallon tank????

03/07/2010, 07:36 PM
LOL! It's a 65 gal. tank.

Update: After turning off my metal halides and retesting pH 30 minutes later, pH had dropped to 8.4! I'm seeing now that there really is a relationship between aeration and pH as Jonathan mentioned - and the metal halides cause the pH to climb. Thanks Jonathan and everyone for helping me figure this out! I've always wanted to know more about pH and today I learned something important. REEF CENTRAL ROCKS!!! :)

03/07/2010, 07:41 PM
Umm lighting and aeration are two totally different things. Aeration is the amount of "air" being added to the water, via flow, turbulence, skimmer etc.

The reason lighting effects pH has to do with how plant life in your tank consume Co2/O2, depending on if they're photosynthesizing or not. Photosynthesis requires light. During the day, algae consumes Co2 and expels O2. At night, algae consumes o2. So, in a way, I guess lights do effect "aeration," in that they effect algae processing and creating oxygen.

I still think your test results are inaccurate.

03/08/2010, 04:54 AM
^Would have to agree. Something seems wrong. Many people do have PH swings because of lights, just as sid explains above. By no means should you be getting 8.8 on your high side tho.

What type of sand are you using?