If its not CO2, then why low pH

[Randy Holmes-Farley]

This finally gives me a definitive answer, but can H+ addition from biotic process depress pH?

Since its CO2, I'd like to see if its atmospheric or something going on in the aquarium itself.

Yes, H+ from a biological process (such as conversion of ammonia to nitrate) will deplete alkalinity and also lower pH.

 

[josephxsxn]

Looks like Randy brought up the aeration test which is a good thing to do. I have always seen an improvement with sample water when doing that. More gas exchange via better skimmer could make sense as well if you didn't see results from the outdoor skimmer line.

 

[Biologic]

Yes, H+ from a biological process (such as conversion of ammonia to nitrate) will deplete alkalinity and also lower pH.

I'd assume that not only is CO2 is an issue, but also the calcium formate, which is carbon dosing, which could drive down pH. Or CO2 from my environment outside of the aquarium isn't a problem at all, hence why the effect of the CO2 scrubber, isn't working. It's all inside the aquarium from abiotic processes.

 

[Randy Holmes-Farley]

I'd assume that not only is CO2 is an issue, but also the calcium formate, which is carbon dosing, which could drive down pH. Or CO2 from my environment outside of the aquarium isn't a problem at all, hence why the effect of the CO2 scrubber, isn't working. It's all inside the aquarium from abiotic processes.

IMO, dosing formate for alkalinity has exactly the same effect on pH as bicarbonate, recognizing that the consumption and pH effects of the formate are spread out in time, while the bicarbonate effect hits all at once when dosed.

 

[Biologic]

You are on the right track here. Dosing kalk in an ATO is problematic due to differences in evaporation with the seasons. Best to run it as a separate fixed dosing amount, set to slightly less than your minimum daily evaporation and let your ATO make up the difference in the dryer months.

Perfect, nice to figure this out. I am tired of the low pH.

The erlenmeyer flask with the stopper and 2 tubes, posted earlier, is a great idea for smaller tanks. Toss in a spin bar and set it on an inexpensive mixing plate from Amazon and you have a nice little kalk setup. Operate the mixing plate for a minute or 2 at least once a day, with a pause in dosing for settlement after the mixing.

I just ordered a 1 liter flask with a bung. Spin bar -- I don't necessarily need a super saturated slurry solution being dosed. I just want the pH offset from the saturated solution. I still like the concept of All4Reef, because of the simplicity of the major/minor/trace replacement.

Because you will still be limited by evaporation, you can make up the difference in consumption with All-For-Reef. Just like you make up the difference in evaporation in the drier months using your ATO.

Dennis

Absolutely, I am going to have to play with the All For Reef. If I can get a stable pH, that's better than the giant diurnal swing going in the 7.6's pH units.

Thank you for the reply and the encouragement.

 

[Biologic]

IMO, dosing formate for alkalinity has exactly the same effect on pH as bicarbonate, recognizing that the consumption and pH effects of the formate are spread out in time, while the bicarbonate effect hits all at once when dosed.

Interesting. I use the DIY All For Reef. Of calcium formate, I am using 19.7 grams / 100 grams of H2O. Which is a super saturation, but when mixing in Tropic Marin Trace A- and Tropic Marin Trace K- is said to "chelate" the undissolved calcium formate into solution.

Of this DIY All4Reef solution, I dose 20 mL per 100 L over the course of 24 hours using the Neptune DOS. This has produced very stable alkalinity for me of around 8 dKH.

 

[Biologic]

Looks like Randy brought up the aeration test which is a good thing to do. I have always seen an improvement with sample water when doing that. More gas exchange via better skimmer could make sense as well if you didn't see results from the outdoor skimmer line.

I really like that thread in your signature. That's a big help for demystifying the relationship of Alkalinity + CO2 yielding X pH. Seeing it in the graph really made me grasp that concept.

 

[Biologic]

That pH drop is not unexpected.

The drop is pretty low, but it also may not be accurate.

Low pH is always caused by high CO2 in the water (if alk is normal) and usually that means high CO2 in teh home air (only other possibility is inadequate aeration).

If you want to use a two part instead of kalkwasser, you can get the same ph boost using a very high pH two part made from sodium hydroxide for the alk part.

This has more on CO2:

pH And The Reef Aquarium
http://www.reefedition.com/ph-and-the-reef-aquarium

from it:

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.

Process to test this theory --

1.) Recalibrated Apex pH probe, I believe its fairly accurate. Put it into pH of 7, it's 7. Put it in 10. It's 10. Calibrated using TC in Apex. I keep my tank at 77-78.
2.) Purchased a Milwaukee MW-101. Calibrated both probes in the same calibration solution. Put it 7, its 7, put it in 10, it's 10. Also used a lab grade mercury temp to set temperature correction at 25 degrees C.
3.) Place both probes into the same calibration fluid, they both agree on the same 7 and 10 pH ranges down to 0.01.

Where things start to diverge ---

4.) Do both probes agree in the tank water -- NO -- 7.84 pH (Apex) vs 7.94 pH (Milwaukee). I am not totally upset about a 0.1 difference but fine, as long as both instruments are repeatable? Right?! ---- Though I cannot understand why. Probe differences? Should I buy another APEX probe for the Milwaukee?

The Aeration Test -- "Rubber Meets the Road" ---

5.) Using the Milwaukee MW-101, performing the 1 hour long outside aeration test moved the pH from 7.95 to 8.15. Performed at the hours of 10:30 PM to 11:30 PM. An increase.
6.) Performing the same test, but inside near the tank results from the sample taken at 11:30 PM to 12:30 of a pH from 7.90 (new sample water taken from the tank) to 7.88. Picture of the apparatus attached.
7.) Moving the Milwaukee MW-101, back to the tank, the pH is time 12:36 to a pH of 7.86 to sit for 5 minutes for a stable reading. The Apex reads a pH of 7.76 units.




So what does this tell me?

With a stable tank alkalinity, indoor CO2 is affecting the pH of my tank. As seen from my outdoor aeration, the pH rises. Indoor test shows the pH stays almost the same. Though, my house is quite old (1968) with original awful windows, I have a skimmer pulling outdoor air, the CO2 is here. I could try a bigger skimmer to bring in more outdoor air. I can also use CaOH to raise my pH.

Will scrubbing CO2 fix my issues?

No. From my tests, I haven't seen a significant difference, with or without. Doesn't move the meter. Though I still need to try other brands of media that are reported to work better. I will try this again.

Also attached the pH of the tank water from the Apex - rapidly dropping as time goes along.


Any other observations? Suggestions?

 

[DrZoidburg]

are you using sodium carbonate and calcium diformate?

 

[Biologic]

are you using sodium carbonate and calcium diformate?

I am using the DIY All For Reef -- Carbocalcium which is said to be calcium formate, magnesium formate, and minor and trace elements. Though we've determined the affect on pH is the same as sodium carbonate per Randy.

Some additional data and a control --
I set up another tank in the house, nano tank, no skimmer, no filter, just fish and live rock, it also reads just now 7.88.

Control -- I have a bucket of saltwater, loosely covered, no mixing, or aeration, I mixed about 5 days ago, IT TOO READS 7.88.

 

[DrZoidburg]

I am using the DIY All For Reef -- Carbocalcium which is said to be calcium formate, magnesium formate, and minor and trace elements. Though we've determined the affect on pH is the same as sodium carbonate per Randy.

Some additional data and a control --
I set up another tank in the house, nano tank, no skimmer, no filter, just fish and live rock, it also reads just now 7.88.

Control -- I have a bucket of saltwater, loosely covered, no mixing, or aeration, I mixed about 5 days ago, IT TOO READS 7.88.

 

[DrZoidburg]

I don't exactly know what's in trace k. K stands for is potassium and it is more reactive than calcium. Calcium formate has 2 formates. Potassium formate has one formate. If its not balanced out right you could be having an excess of formate. I am assuming they use potassium chloride in trace K. I don't know what's in trace A. Have you tested your diy solution for ph? Did you test your source water? If your salt water test bucket wasn't dosed with diy stuff before testing I would also assume that either you have a bad salt mix with high chlorinity or source water with something acidic. What should it mix up at?

 

[josephxsxn]

As for the instruments being different they both will come with an accuracy rating so of they are reading within the accuracy that's acceptable.

What skimmer do you have? How long is the pull for the outdoor air, while I have never seen it I do seem to recall reading that the longer the line to outdoors the less effective it will be (suction problem.)

 

[KimG]

I am using the DIY All For Reef -- Carbocalcium which is said to be calcium formate, magnesium formate, and minor and trace elements. Though we've determined the affect on pH is the same as sodium carbonate per Randy.

Some additional data and a control --
I set up another tank in the house, nano tank, no skimmer, no filter, just fish and live rock, it also reads just now 7.88.

Control -- I have a bucket of saltwater, loosely covered, no mixing, or aeration, I mixed about 5 days ago, IT TOO READS 7.88.

Not sure you will easily solve the pH issue without dosing.
Its clear you problem is CO2 in the house (all your tests show the same result).
Per your results, the All for reef does not seem to be the problem. It simply is not helping solving it either.

To increase you pH via simple aeration to your tank, you would have to have a larger exchange via the skimmer then via everywhere else (e.g. surface agitation).
You stated you have SPS, so I'm assuming you have a lot of flow and therefore you probably also have a lot of surface agitation. This probably means you have a large transfer of gases between your tank and the inside air, which is always rebalancing your tank to a lower pH. Bigger skimmer could help, but it still may not be the all solution (depending on gas transfers).

 

[FishTruck]

Did someone suggest... an air quality monitor to measure your CO2 levels in the house and around the tank?, (so you can work on ventilation with quick data feedback).

 

[capted]

Some good testing. So it seems to be high co2 in your house. Keep in mind the more agitation on the surface water will add more co2 to the tank as was stated. A bigger skimmer with outside air should help. I can only say this because I had the same issue. I had 7.8 - 7.9 with inside air to my skimmer. Plumbed a 3/4" pvc pipe to outside air(only about 10 feet with 1 elbow) and ph rose to 8.0 - 8.05. Next I added a co2 scrubber (di resin canister with 1/2" ports) and the ph is now 8.15 - 8.25. My house is pretty sealed and loaded with kids and animals. Well the kids do unseal the house with the freaking doors always opening. Ha!! Also it took about 2 days to see the ph change after each test. As someone stated the air line can't be too small or it will choke the skimmer. The main reason why I say maybe you need a bigger skimmer is because with a smaller skimmer my ph slightly rose from 7.8 to maybe 7.83. I use a simplicity dc240 for a 125 gallon tank and my alkalinity is 9.7. I do dose kalkwasser via an ato to maintain alkalinity and calcium and do a 15% water change weekly. Hope this helps you a bit.

 

[Shirak]

Were you using the CO2 scrubber in a recirculating manner with a tiny bit of water at the bottom of the scrubber canister?

 

[capted]

Were you using the CO2 scrubber in a recirculating manner with a tiny bit of water at the bottom of the scrubber canister?

Not recirculating but I add a little ro water every 3 to 4 days to the bottom of the canister.

 

[Shirak]

Not recirculating but I add a little ro water every 3 to 4 days to the bottom of the canister.

Might be worth the effort to set it for recirculating the skimmer air so you are pulling CO2 directly from the tank water. From my understanding you can drive pH way up to 8.6 and higher with such a setup. To the point it needs some control to keep it from going too high.

 

[Biologic]

I don't exactly know what's in trace k. K stands for is potassium and it is more reactive than calcium. Calcium formate has 2 formates. Potassium formate has one formate. If its not balanced out right you could be having an excess of formate. I am assuming they use potassium chloride in trace K. I don't know what's in trace A. Have you tested your diy solution for ph? Did you test your source water? If your salt water test bucket wasn't dosed with diy stuff before testing I would also assume that either you have a bad salt mix with high chlorinity or source water with something acidic. What should it mix up at?

I haven’t read the actual fluid itself but I’ve looked up Calcium Formate pH —

pH	6.0-8.0 (25 °C, 1 M in H2O)

Even still, I am dosing 20 mL into the tank.
Source water is RO/DI which the pH on a meter won’t read correctly because of lack of ions. The DIY all for reef is made correctly. Alkalinity is rock solid.

all tanks and salt water are the same pH even if I don’t use it. So I am eliminating All For Reef

As for the instruments being different they both will come with an accuracy rating so of they are reading within the accuracy that's acceptable.

What skimmer do you have? How long is the pull for the outdoor air, while I have never seen it I do seem to recall reading that the longer the line to outdoors the less effective it will be (suction problem.)

A Deltec MCE300 - uses a maxi jet needle wheel impeller. It’s uncommon. It’s rated for a 75 gallon tank. Great skimmer though it’s 14 years old. Works better than most HOB’s. Produces real skim .

I hooked up the airline outside and I saw no difference in skim mate production. Or flow through the system.

Not sure you will easily solve the pH issue without dosing.
Its clear you problem is CO2 in the house (all your tests show the same result).
Per your results, the All for reef does not seem to be the problem. It simply is not helping solving it either.

To increase you pH via simple aeration to your tank, you would have to have a larger exchange via the skimmer then via everywhere else (e.g. surface agitation).
You stated you have SPS, so I'm assuming you have a lot of flow and therefore you probably also have a lot of surface agitation. This probably means you have a large transfer of gases between your tank and the inside air, which is always rebalancing your tank to a lower pH. Bigger skimmer could help, but it still may not be the all solution (depending on gas transfers).

I have a ton of flow in the tank. Though I am happy I got this one result. I will re-test again to prove it.

the skimmer may not work. The surface area of the water might pull it all back in anyways.

Did someone suggest... an air quality monitor to measure your CO2 levels in the house and around the tank?, (so you can work on ventilation with quick data feedback).

I have a monitor, but have not ran that instrument yet. It’s a HVAC quality CO2 monitor.

Some good testing. So it seems to be high co2 in your house. Keep in mind the more agitation on the surface water will add more co2 to the tank as was stated. A bigger skimmer with outside air should help. I can only say this because I had the same issue. I had 7.8 - 7.9 with inside air to my skimmer. Plumbed a 3/4" pvc pipe to outside air(only about 10 feet with 1 elbow) and ph rose to 8.0 - 8.05. Next I added a co2 scrubber (di resin canister with 1/2" ports) and the ph is now 8.15 - 8.25. My house is pretty sealed and loaded with kids and animals. Well the kids do unseal the house with the freaking doors always opening. Ha!! Also it took about 2 days to see the ph change after each test. As someone stated the air line can't be too small or it will choke the skimmer. The main reason why I say maybe you need a bigger skimmer is because with a smaller skimmer my ph slightly rose from 7.8 to maybe 7.83. I use a simplicity dc240 for a 125 gallon tank and my alkalinity is 9.7. I do dose kalkwasser via an ato to maintain alkalinity and calcium and do a 15% water change weekly. Hope this helps you a bit.

Thank you for sharing. This will definitely give me a good direction.

Might be worth the effort to set it for recirculating the skimmer air so you are pulling CO2 directly from the tank water. From my understanding you can drive pH way up to 8.6 and higher with such a setup. To the point it needs some control to keep it from going too high.

I’ve added a CO2 scrubber. I do not think it’s enough air draw to effectively scrub the air.