constant low pH

[archgetty]

I have read the posts about low pH but none of them describe my situation.

My daytime pH is around 8.0. Nighttime 7.7. I would like 8.3.

130 gal tank

- Alk: 9.5
- CA: 450
- Mag: 1350
- Kalkwasser ATO
- supplemental dose All-For-Reef
- Tank is in a room next to big doors which are always open to outside air. (I live in Los Angeles)
- 20% water change weekly

- 2 quality pH probes, calibrated up to date

I'm tempted to add a buffer but fear that my Alk might go through the roof.

Any suggestions welcome!

 

[Biglew11]

Are you running a refugium on opposite light schedule?

Can you take a nighttime sample whe ph is low and aerate it to see if the ph comes back up?

I wouldn't add anything just to chase a ph number.

 

[CoralB]

If you have a skimmer you could try to add a co2 scrubber on the intake of that skimmer . I know you said the two doors are always open and with your alk in good standing that’s the only thing I could suggest .

 

[archgetty]

Are you running a refugium on opposite light schedule?

Can you take a nighttime sample whe ph is low and aerate it to see if the ph comes back up?

I wouldn't add anything just to chase a ph number.

Thanks! Yes, refugium on opposite light schedule. Also algae scrubber ditto. Tried aeration already.

 

[Randy Holmes-Farley]

Adding a "buffer" is a poor idea pushed by marketers that either do not understand chemistry, or don't care about being honest.

You are using a low pH alk method. Other alk methods can give a substantial pH boost.

I suspect pH measurement error if the doors are always open, but try this aeration test:

pH and the Reef Aquarium - REEFEDITION

by Randy Holmes-Farley For many aquarists, pH is not something that they have much experience with aside from their aquarium. For many, pH is almost a black box measurement: something to be considered, but whose physical meaning makes little sense to them. This article will Read more here...

www.reefedition.com

The Aeration Test

Some of the possible causes of low pH listed above require an effort to diagnose. Problems 3 and 4 are quite common, and here is a way to distinguish them. Remove a cup of tank water and measure its pH. Then aerate it for an hour with an airstone using outside air. Its pH should rise if it is unusually low for the measured alkalinity (Figure 2). Then repeat the same experiment on a new cup of water using inside air. If its pH also rises, then the aquarium’s pH will rise simply with more aeration because it is only the aquarium that contains excess carbon dioxide. If the pH does not rise in the cup (or rises very little) when aerating with indoor air, then that air likely contains excess CO2, and more aeration with that same air will not solve the low pH problem (although aeration with fresher air should). Be careful implementing this test if the outside aeration test results in a large temperature change (more than 5°C or 10°F), because such changes alone impact pH measurements.

 

[Randy Holmes-Farley]

Thanks! Yes, refugium on opposite light schedule. Also algae scrubber ditto. Tried aeration already.

If alk is above 6 dKH and sufficient aeration with outside air does not raise pH above 7.9, then you have a pH measurement issue, not a low pH issue.

 

[dblhelix]

Adding a "buffer" is a poor idea pushed by marketers that either do not understand chemistry, or don't care about being honest.

You are using a low pH alk method. Other alk methods can give a substantial pH boost.

I suspect pH measurement error if the doors are always open, but try this aeration test:

pH and the Reef Aquarium - REEFEDITION

by Randy Holmes-Farley For many aquarists, pH is not something that they have much experience with aside from their aquarium. For many, pH is almost a black box measurement: something to be considered, but whose physical meaning makes little sense to them. This article will Read more here...

www.reefedition.com

The Aeration Test

Some of the possible causes of low pH listed above require an effort to diagnose. Problems 3 and 4 are quite common, and here is a way to distinguish them. Remove a cup of tank water and measure its pH. Then aerate it for an hour with an airstone using outside air. Its pH should rise if it is unusually low for the measured alkalinity (Figure 2). Then repeat the same experiment on a new cup of water using inside air. If its pH also rises, then the aquarium’s pH will rise simply with more aeration because it is only the aquarium that contains excess carbon dioxide. If the pH does not rise in the cup (or rises very little) when aerating with indoor air, then that air likely contains excess CO2, and more aeration with that same air will not solve the low pH problem (although aeration with fresher air should). Be careful implementing this test if the outside aeration test results in a large temperature change (more than 5°C or 10°F), because such changes alone impact pH measurements.

Randy,
My reef tank suffers from 7.59 at night to 8.0 pH in the day range. A few months back the pH was about 8.0-8.4. I use All for Reef and not 2 part or Kalk. All is about 8.6 and calcium is about 460. I have a great refugium that I have to harvest at least once a month running the light on it only at night.

The only thing I changed was I added 22 more pounds of sand because a watchman gobi hoarded about 1/4 of the existing sand in one corner to build his home resulting in a big bare spot in the middle of the tank where the powerheads create the most current. I used to have only about 1 inch of sand and now that is about 2". Its a 73 gallon tank with 18 gallon sump. Do you think this sand addition has maybe increased the carbonic acid and lowered my pH. Have you ever heard of this happening? Thank you.