Testing the Aqua Rocks Colorado Acrylic Horizontal CO2 Reactor on a large tank

[PeerUnk]

A 1.5pH drop would be 45ppm. However, this is all at 2-16 kH (because kH has a direct effect on pH).

as pH/Co2 is logarithmic, I guess CO2 from 3 to 45 ppm would mean a Log(15) = 1.2 pH drop instead of the mentioned 1.5, right?

In normal non-Injected aquariums, CO2 is about 3ppm.

Not sure CO2 would be 3ppm in all 'normal' aquariums... At least in my heavily planted aerated tank it is between 1.2 and 2 ppm ... I will test your hypothesis soon, shutting down aeration for 24-48 hours and monitor CO2 and pH. I guess CO2 will be higher before lights go on, and will be almost depleted (0.5 ppm ?) at the end of the day.

In my tanks with zero kH, a 1.0pH drop might only equate to ~20-25ppm CO2. That's why a pH drop of 1.75 might only be ~45ppm CO2 for me, because of a low-kH environment.

I know calculating CO2 by using the pH only works accurately when there is some decent amount of alkalinity/carbonate buffering. Otherwise other factors come into play, like the phosphate buffering system, I guess Rocco is aware of that.

So at lower KH tanks, there is no such thing as using a pH drop to determine a roughly guessed CO2 change. One just needs to measure CO2 directly I guess?

This is assuming that the pH drop is measured from the true de-gassed baseline.

But what is a 'true de-gassed baseline'? I've come across the pH drop thingy frequently, but does everyone use such de-gassed baseline, and how to determine and use such a thing?
Is there a common procedure to establish this?

Cheers!

 

[PeerUnk]

@Naturescapes_Rocco Nice effort you've put in this thread BTW

 

[Kwyet]

as pH/Co2 is logarithmic, I guess CO2 from 3 to 45 ppm would mean a Log(15) = 1.2 pH drop instead of the mentioned 1.5, right?


Not sure CO2 would be 3ppm in all 'normal' aquariums... At least in my heavily planted aerated tank it is between 1.2 and 2 ppm ... I will test your hypothesis soon, shutting down aeration for 24-48 hours and monitor CO2 and pH. I guess CO2 will be higher before lights go on, and will be almost depleted (0.5 ppm ?) at the end of the day.


I know calculating CO2 by using the pH only works accurately when there is some decent amount of alkalinity/carbonate buffering. Otherwise other factors come into play, like the phosphate buffering system, I guess Rocco is aware of that.

So at lower KH tanks, there is no such thing as using a pH drop to determine a roughly guessed CO2 change. One just needs to measure CO2 directly I guess?


But what is a 'true de-gassed baseline'? I've come across the pH drop thingy frequently, but does everyone use such de-gassed baseline, and how to determine and use such a thing?
Is there a common procedure to establish this?

Cheers!

I’ve actually read that 4 ppm is common in non-injected aquariums, but that it can even be influenced by elevation and the level of air pollution (city versus rural).

I see a lot of recommendations about how to get a true de-gassed baseline. I can tell you that just aerating it for 4 hours or shaking it vigorously for several minutes or even leaving it out for 24 hours didn’t yield the same pH for me as leaving it out for 48 hours. This was when I tried those methods in Florida with a kH of 3 and a gH of 6 and was using an Apera pH pen. There’s a thread here (may have been one of @Yugang ‘s) that said to get the most accurate reading, the water sample should be left outdoors, because CO2 levels are higher indoors. I remember trying it, and there was a very small difference, but since my water here was 0-1 kH at the time, I guess the readings may not have been as useful as I thought.

 

[Naturescapes_Rocco]

as pH/Co2 is logarithmic, I guess CO2 from 3 to 45 ppm would mean a Log(15) = 1.2 pH drop instead of the mentioned 1.5, right?

You might be right about this one, I think!

Not sure CO2 would be 3ppm in all 'normal' aquariums... At least in my heavily planted aerated tank it is between 1.2 and 2 ppm ... I will test your hypothesis soon, shutting down aeration for 24-48 hours and monitor CO2 and pH. I guess CO2 will be higher before lights go on, and will be almost depleted (0.5 ppm ?) at the end of the day.


I know calculating CO2 by using the pH only works accurately when there is some decent amount of alkalinity/carbonate buffering. Otherwise other factors come into play, like the phosphate buffering system, I guess Rocco is aware of that.

So at lower KH tanks, there is no such thing as using a pH drop to determine a roughly guessed CO2 change. One just needs to measure CO2 directly I guess?

It still might be useful once you get a sense for what the relative pH actually means (in my <1 kH tank, I know that a pH drop of 1.75 means my fish start gasping at the surface, so closer to 40-50ppm, whereas 1.5pH has no fish gasping so is likely closer to 30ppm CO2, if I had to guess.

But what is a 'true de-gassed baseline'? I've come across the pH drop thingy frequently, but does everyone use such de-gassed baseline, and how to determine and use such a thing?
Is there a common procedure to establish this?

The most common is to leave a small sample of your aquarium water in a cup, exposed to your indoor air, for 24 hours (as CO2 will naturally de-gas until reaching atmospheric equilibrium).

However, a faster and sometimes more effective way is intense agitation... see my original post in this thread:

Dissolved CO2 gas has a direct effect on lowering pH in our aquariums. There is also some relation with kH (a reading of carbonate hardness in your water). For most tanks between ~2-6kH, a 1.0pH drop equals about 30ppm CO2, which is high and ideal for growing plants, and my target for CO2 injection. I have extremely low KH tanks (between 0 and 1, I can't actually test it with the API test kits it's so dilute). With KH this low, you might need a 1.4 or 1.5 pH drop

The "Drop" is the difference measured between your CO2-injected tank water, and from a sample of your tank water that has been completely de-gassed of all dissolved CO2. You can degas a sample by leaving it out open-top on your counter for 24-48 hours, or through aggressive agitation (blending, stir plate, vigorous shaking).

The most "scientific" method is to use a pH probe/pen and a stir plate+stir bar, and seriously agitate your aquarium water sample. Another method is to literally blend your water in a blender, open it up to the air in between blending, and blend some more. Some users suggest shaking vigorously, but I tested a jar I shook for 10-15 minutes until my arms were tired vs a stir plate with stir bar viciously agitating the water sample, and found that even after 10 minutes of vigorous shaking I still didn't degas my sample.
You know your sample is degassed if it's the same pH reading after you've degassed it, and take another reading 24-48 hours later. If the pH is the same, it's free of CO2. You can also use a pH probe to ensure it has properly degassed:


You can see I used my pH probe at 8am to find the degassed sample pH. I then tested it again at around 1pm until the next morning, pH probe sitting in the sample cup. I got pretty close to degassed at 1pm, but even letting it sit overnight continued to degas the sample (pH rises).

 

[PeerUnk]

It still might be useful once you get a sense for what the relative pH actually means (in my <1 kH tank, I know that a pH drop of 1.75 means my fish start gasping at the surface, so closer to 40-50ppm, whereas 1.5pH has no fish gasping so is likely closer to 30ppm CO2, if I had to guess.

Okay, I get it, thanks. Out of curiosity, do you recalibrate the pH degas baseline once and a while, as it might shift at low KH (HCO3) and other fluctuating compounds like PO4?

The most common is to leave a small sample of your aquarium water in a cup, exposed to your indoor air, for 24 hours (as CO2 will naturally de-gas until reaching atmospheric equilibrium).

Please be aware degassing indoors does not mean it would create a steady baseline. Indoor CO2 can fluctuate between 420 and 1500 ppm easily, depending on the room size and presence of people in the room. That would be almost a factor 4 in CO2 ppm , or Log(4) =0,60 pH. Quit a difference.

And temperature is a consideration as well, as degassing at 20*C room temperature, will give a different pH than tank water at 25.

The most "scientific" method is to use a pH probe/pen and a stir plate+stir bar, and seriously agitate your aquarium water sample. Another method is to literally blend your water in a blender, open it up to the air in between blending, and blend some more. Some users suggest shaking vigorously, but I tested a jar I shook for 10-15 minutes until my arms were tired vs a stir plate with stir bar viciously agitating the water sample, and found that even after 10 minutes of vigorous shaking I still didn't degas my sample.
You know your sample is degassed if it's the same pH reading after you've degassed it, and take another reading 24-48 hours later. If the pH is the same, it's free of CO2. You can also use a pH probe to ensure it has properly degassed:

Nice test and graph, thank you for sharing.
What I do at my place is aerate a sample of 500ml in a bottle with an air pump for 2 hours, outside the house.
Not for the application you use, but with a degassed a sample outside 420 ppm and a temperature, I calculate the amount of CO2 in the water. And measuring the pH of the sample, I calculate the KH. I find this more accurate than a KH drop test. And as mentioned in an earlier post, this method won’t work <1 dKH.

 

[Naturescapes_Rocco]

Please be aware degassing indoors does not mean it would create a steady baseline. Indoor CO2 can fluctuate between 420 and 1500 ppm easily, depending on the room size and presence of people in the room. That would be almost a factor 4 in CO2 ppm , or Log(4) =0,60 pH. Quit a difference.

And temperature is a consideration as well, as degassing at 20*C room temperature, will give a different pH than tank water at 25.

No worries, I'm definitely aware! I have a degree in biochemistry. I think for the average hobbyist, the pH drop method is all relative, not absolute, in my mind. Yes, indoor CO2 has an effect, yes temperature has an effect, yes kH/Phosphates/unknown reactions are all at play, but for the average hobbyist getting +-10ppm CO2 readings in their water is good enough, as long as CO2 is stable and not rapidly fluctuating throughout the day (most important part IMO!).

In the end, I find that plant growth/health and inhabitant comfort level is usually the most important CO2 reading in the end (I just love the testing/science side of it). As long as your plants are pearling and outcompeting algae, and your inhabitants aren't adversely affected, AND your injection method reaches equilibrium and stays stable for the photoperiod, it almost doesn't matter if it's 20ppm, 30ppm 40ppm, or anything in between!

 

[PeerUnk]

No worries, I'm definitely aware! I have a degree in biochemistry. I think for the average hobbyist, the pH drop method is all relative, not absolute, in my mind. Yes, indoor CO2 has an effect, yes temperature has an effect, yes kH/Phosphates/unknown reactions are all at play, but for the average hobbyist getting +-10ppm CO2 readings in their water is good enough, as long as CO2 is stable and not rapidly fluctuating throughout the day (most important part IMO!).

True, that's why a CO2 bell (or the horizontal reactor with overflow) for diffusion is great. It just can't dilute more CO2 than a certain maximum.
For the record, I'm not a CO2 user for more than a decade, but I might do that one day, and if I do, I will definitely use the Yugang 鱼缸 Reactor.

In the end, I find that plant growth/health and inhabitant comfort level is usually the most important CO2 reading in the end (I just love the testing/science side of it). As long as your plants are pearling and outcompeting algae, and your inhabitants aren't adversely affected, AND your injection method reaches equilibrium and stays stable for the photoperiod, it almost doesn't matter if it's 20ppm, 30ppm 40ppm, or anything in between!

True again, and my belief is "The more stable CO2 is, the better." I love testing and science as well, I do it a lot with my aerated tank, exploring what CO2 levels are in that realm. And aeration gives a more stable CO2 as well, just at a lot lower level

Cheers!

 

[Yugang]

Thank you @Naturescapes_Rocco for this great thread

 

[gjcarew]

Love the scapes. Fantastic nature aquariums!

 

[musicmanryann]

First off, thank you a TON for starting this thread and being so detailed in your analysis! I have no interest in DIY for this, so I have been looking at the ARC Reactor for awhile now. This thread has put me on a the precipice of making a purchase for me 120x60 comp tank. Before, I have a couple of questions.

The OG Yugang thread talks a lot about flow being a variable to be mindful of when using a Yugang. Specifically, you want a lower flow. My issue is my filter design has A LOT of flow. It appears OP also does, but I didn't see a mention of it. Do I need to worry about flow, or does the design of the ARC reactor take care of it?

With the clear reactor, have you (or anyone else), experienced it getting gunked up over time, like clear filter tubing/lily pipes? This would bother me and it appears would be kind-of a pain to clean regularly like I do my tubing? I keep going back and forth on clear versus stainless and this may be a deciding factor/

I have two filters on my tank. Is there any extra consideration should give based on this? Part of me thinks I should get two smaller ones and set up a reactor on each, and the other part of me tells me I'm over thinking it and just get one and call it a day.
Thanks in advance for the consideration!

 

[Naturescapes_Rocco]

Happy to help!

Do I need to worry about flow, or does the design of the ARC reactor take care of it?

I don't think it has ever mattered much. IIRC, Yugang mostly said a slower flow just to prevent splashing noise. Otherwise, there is no issue with high flow systems.
I have mine on a modified (more powerful than stock) Biomaster 2 850. It's quite strong flow through the reactor and it still works perfectly fine! If I run it at max power, I do hear a slight trickling noise from subtle splashing, but it's barely noticeable at all.

With the clear reactor, have you (or anyone else), experienced it getting gunked up over time, like clear filter tubing/lily pipes? I keep going back and forth on clear versus stainless and this may be a deciding factor.

Algae/gunk will only grow where light can hit it, so if you have it inside your stand this wont be a problem.

Mine has been running nonstop for a few months now and it does have a bit if detritus/mulm/bacteria buildup, but no more than all canister tubing develops, and it's only on the bottom 1/3rd of the reactor. It doesn't look pristine anymore, but it doesn't bother me nor does it look gross/unclean. It just looks like equipment. I would HIGHLY recommend a clear reactor, for reasons I stated previously in this thread. I would never use an opaque reactor unless I had to for some reason after my experience.

I have two filters on my tank. Is there any extra consideration should give based on this? Part of me thinks I should get two smaller ones and set up a reactor on each, and the other part of me tells me I'm over thinking it and just get one and call it a day.

I am currently running two filters (both modified Biomaster 2 850s). I have the reactor on just one of the filters, and that's all that is needed.
From earlier in the thread, remember that I have a 150cmx60cmx60cm tank, and about 120-130 gallons of water. The larger sized ARC reactor (the one I have) is actually somewhat overpowered for my tank, so even just one reactor is more than enough.

Since your two filter setup sounds similar to mine, I'd put it on either filter (Ideally the slower/smaller one) and call it a day!
Let me know if you have any questions.

 

[Yugang]

The OG Yugang thread talks a lot about flow being a variable to be mindful of when using a Yugang. Specifically, you want a lower flow.

I mention flow because I try to find the maximum performance of the reactor. Zero noise, and perfect operation in overflow. Call me a perfectionist.
However, the reactor will work with almost all flow that is not stagnant, and I guess 95% of users will be perfectly happy with it, even at high flows.

I have experimented with shaping the inlet of the reactor, so that even at high flow there is no splashing and no noise.