Nano Reef Very Low pH- What to Do?

[Zakary2003]

I have a waterbox 20 cube. My tank's pH before I moved was about 8.3 during the day and dropped to around 7.9 at night, measured with a calibrated apex pH probe. When I moved in mid May, I noticed much lower pH for both day and night. If these readings are right, that would mean my pH is getting extremely low at night at 7.22. I assumed the probe must not be calibrated correctly, so I didn't worry too much.

I recalibrated my pH probe 2 days ago with brand new Neptune brand 7.00 and 10.00 calibration solutions from Bulk Reef Supply. The readings did not change, so either my probe is broken (it was transported wet and calibrated fine, so this is unlikely) or I need to find a solution.

The home HVAC system where I am currently living sucks, so circulation in my bedroom is very poor and CO2 is probably pretty high. I have a HOB aquaclear refugium (added only a few weeks ago) and HOB aquaclear skimmer, neither of which seems to be effective enough at stabilizing pH.

My alkalinity is around 8 dkh, measured with a hanna checker. I really don't feel like other params matter in this scenario, so I won't list them. Even when I do list everything, people still ask me about them anyways.

I am working with a nano reef AIO, so I can't really do a scrubber. I dose All For Reef with great success, so I am not willing to switch to 2 part to raise pH. I could add kalkwasser to my auto top off water, but I'm not sure that would be very reliable. I don't think I can add a CO2 scrubber to my skimmer since it's so small and I have such limited space.

My local fish store recommended Brightwell Aquatics pH+, but I have no experience with that product and they have tried to sell me useless or dangerous solutions in the past. I have one dosing head free, since I stopped dosing carbon now that my fuge seems to be controlling nitrates and phosphates effectively.

 

[kingranch2003]

Hello, hopefully we can all help you fix this. Is your flow significantly reduced at night? Are wavemakers, return pump(s) etc. turned down at night? If this is an all in one, make sure you have a waterfall of varying heights in the back chambers to pull that film off the top and help with proper gas exchange on the surface.

 

[Mr. Mojo Rising]

Is there a powerhead in the tank? A powerhead pointed upwards to the surface will create much more surface agitation than a hob will.

 

[Zakary2003]

Hello, hopefully we can all help you fix this. Is your flow significantly reduced at night? Are wavemakers, return pump(s) etc. turned down at night? If this is an all in one, make sure you have a waterfall of varying heights in the back chambers to pull that film off the top and help with proper gas exchange on the surface.

No, the flow is about the same at night vs the day. Flow is handled by 2 ai neros that are set between 30 and 60% power. The return pump is an AI axis 20 set to 60% power. I can't lower the back chamber levels too much because it messes up the HOB refugium and skimmer. Their intakes don't go deep enough. I have a PC fan attached to the top of the tank for temperature control, since my tank gets too hot during the day. It runs about half the time and causes a lot of agitation.

 

[Zakary2003]

Is there a powerhead in the tank? A powerhead pointed upwards to the surface will create much more surface agitation than a hob will.

There are two AI nero powerheads. One is near the survace. Water movement is not an issue. I also have a PC fan used to cool the tank that runs about half the time, and it creates a lot of air movement and surface agitation.

 

[Randy Holmes-Farley Verified Community Expert]

I do not believe those values around 7.3 are accurate. Rock and sand (and coral skeletons) would be dissolving reasonably fast, boosting alk and pH. Try this aeration test:

http://www.reefedition.com/ph-and-the-reef-aquarium/
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 Verified Community Expert]

I do not believe those values around 7.3 are accurate. Rock and sand (and coral skeletons) would be dissolving reasonably fast, boosting alk and pH. Try this aeration test:

http://www.reefedition.com/ph-and-the-reef-aquarium/
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.

 

[Zakary2003]

I do not believe those values around 7.3 are accurate. Rock and sand (and coral skeletons) would be dissolving reasonably fast, boosting alk and pH. Try this aeration test:

http://www.reefedition.com/ph-and-the-reef-aquarium/
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.

I did that test, and the pH rose from 7.40 to 8.21 when aerated with outside air, but only rose from 7.53 to 7.83 with inside air. Does that mean I have a CO2 problem inside my house?

I found someone on r2r that used a BRS CO2 reactor and an air pump/stone to add a CO2 scrubber to a nano tank. I might try that, since it seems like a pretty good solution.

 

[Pistondog]

Try adding an airstone to your tank.
can you run an airline from outside to your skimmer?

 

[Randy Holmes-Farley Verified Community Expert]

It means aeration is poor, and also that you have very high indoor CO2.