CO2 Balancing

[fjf888]

I recently switched my CO2 diffusion from a CO2 reactor to running it through a RIO 800 powerhead with venturi attachment. I did this b/c it addressed a couple issues, misting and added flow.

The results with plant growth were tremendous, but I was still battling small cases of BBA and GDA. I figured with regular EI dosing the issue was CO2 so I gradually bumped up the CO2 daily. The algae improved somewhat, but I had my CO2 revved up so fast that it ran out very quickly.

So I did the following.

1. My lighting is a Current Nova Extreme T5 HO 4x55. I had the 4x55 on for 3 hrs and the 2x55 on for 9 for total of 12 hours. I cut it down to 2x55 to 11 hrs. It is raised about 5-6 inches above the tank. Tank is open air.

2. I minimized the surface chop and directed the flow to both sides of the tank with the dual loc line. (Tank is a predrilled reef tank 72g with sump).

3. I halfheartedly covered the sump with black plastic

I succeeded in gassing a couple fish and causing the rest of the inhabitants serious stress once the CO2 tank ran low, likely thanks to the clippard needle valve (plan to replace that). CO2 ran out in 3 weeks. Before tweaking the CO2, I was up to 2 months with a 5lb tank, which I could live with. I also confirmed there were no leaks in the line, I'm also using Tygon from ACE Hardware.

I'm sort of out of ideas at this point, maybe reduce the photoperiod a bit more.

 

[dutchy]

Misting causes more use of CO2. And I mean A LOT. In my case, it was so much, that I switched back to normal external reactor operation, while continuing extra flow. I've seen good results with enhanced flow without misting.

BBA will take time to beat, it's more about getting new growth that stays algae free. GDA is hardly a CO2 issue IMO, let it live out it's lifecycle for 3 weeks, not cleaning the windows, seems to help. I tried this, but for me it didn't work. It's still there

regards,
dutchy

 

[Gerryd]

Fred,

Using a mazzei on my 180, I use a 10lb every 4-5 weeks.

I don't think I have a leak either.........

 

[dutchy]

I use 4 lb in 6 weeks with external AM1000 reactors on my 180....big difference. Although I'm not sure which of the two is better in the perspective of plant growth....

regards,
dutchy

 

[Tom Barr]

I get 3-4 months from 10lbs on a 180- Gal tank using Needle wheel.

Regards,
Tom Barr

 

[Gerryd]

Hijack in progress...

Dutchy, please read your blog comments on your 180. I had a question or two...

Back to topic.

Well, I like the mist effect myself, but cannot compare the two. I used to use only one AM1000 on my 180 and powered it differently as well.

I keep a 5lb as a spare and just keep refilling and swapping them out.............

 

[Tom Barr]

Less light will "cure" both BBA and GDA, if you can point the light away from the front glass, this also helps. Shorter times, and/or less intensity.

Wait a few weeks, let the plants grow in better/well, really get growing good, then try adding the light back up again, tweak the CO2 etc.

Regards,
Tom Barr

 

[Biollante]

To Bubble Or Not To ... Well You Know...

Hi Fred, All,

The simplest reactors will always be more efficient from a CO2 gas usage point of view.

The plants themselves do not care how the CO2 goes into solution.

Biollante

 

[Gerryd]

Bio,

I think Tom has theorized that the mist may in fact be better assimilated by the plants, and is thus the reason for misting in the first place?

Would not misting vs reactor be a difference in entering solution? If so, and mist is 'better' (not proven), than the plants DO care..

Does that make sense?

Please forgive my questions, just want to ensure I understand....

 

[boink]

Here is another point of view for you guys, going from mazzei to reactor:

I have a 60 gallon (ADA 120P) running with originally, the following:

216 watts of t5ho (8 hrs 2 banks, 4 hrs 2 banks)
CO2 with a mazzei pumped by a 2028, with the bps reallly low (.5-1bps), a 10 lb tank lasts about 4-5 months and tiny mist coming out.
Autodosing every night
Drop checker was green

I had all algae in check except for GSA

I switched to a 24" tall 2" wide reactor, with the bubble count pretty high now--3-4 bps with a light green-green drop checker. The Co2 is 100% dissolved--no bubbles coming out the outtake.
I have bba showing up now, and thinking I may go back to a mazzei.

The only reason i switched was to increase the flow and cut back on the back pressure. I am thinking I will go back to mazzei.

 

[Biollante]

Tom Barr Speculated...

Bio,

I think Tom has theorized that the mist may in fact be better assimilated by the plants, and is thus the reason for misting in the first place?

Would not misting vs reactor be a difference in entering solution? If so, and mist is 'better' (not proven), than the plants DO care..

Does that make sense?

Please forgive my questions, just want to ensure I understand....

Hi Gerry, All,

Gerry your questions are always welcome! I know I am about to step where the do-do is deepest.

In post #8, I was going to let the first sentence stand-alone. However, me being, well me, I set my foot at the edge of the great do-do lake. Fair enough, you called me on my statement.

I have been studying carbon dioxide as it relates to planted aquaria for some time.

I will define a “CO2 reactor” as a device or process that dissolves carbon dioxide into water prior to entering the aquarium proper. For these purposes, Seltzer water supplying the carbon dioxide and would fit the definition of “reactor.”

“Misting” uses the aquarium itself as the principle reactor for these purposes, I do not make any distinction as to how the gas is “processed” prior to entering the aquarium.

I believe that as far as efficiency of carbon dioxide any reactor is superior to any misting system.

As to Tom Barr’s speculations as to the efficacy of “misting” in the Volume 1, Issue 10, October 2005 of The Barr Report, I cannot confirm or refute the speculation, I suspect it is why he speculated. Nothing wrong with educated guesses and a little abductive reasoning that is how we get enough data points to form a testable hypothesis.

So far, in my study and experience I cannot find any support at least that to what passes for my mind, justifies the added expenditure of carbon dioxide.

I can find no evidence that the plants care one way or another, the best evidence is that any bubble larger than 25 microns really do not affect the system to any greater degree than any “dome” or other method that keeps carbon dioxide gas in contact with water for a significant period.

The basic texts I used to begin (first four links require subscription)

• http://www.barrreport.com/showthread...Newsletter-CO2 [FONT=&quot][/FONT]

Methods of delivery of Carbon dioxide (CO2) for submersed aquatic macrophyte fertilization: considerations for adding CO2 gas phase mist
​

This is the basic text and I think an area that set the stage for further exploration.
​

“The bubbles.” I think this is where I get in trouble.
​

• http://www.barrreport.com/showthread...sletter-Carbon

Dissolved Inorganic Carbon (DIC)
​

A tough read, perhaps a little overly condensed.
​

• http://www.barrreport.com/showthread...sletter-Carbon

Dissolved, Particulate and Microbial Biomass Organic Carbon (DOC, MBC, and POC)
​

Good straightforward explanations.
​

• http://www.barrreport.com/showthread...sletter-Oxygen

Oxygen in the Planted Aquarium

Straight forward explanation of Fick’s First Law​

• http://www.rpgroup.caltech.edu/~natsirt/aph162/diffusion.pdf

The Diffusion Equation, A Multi-dimensional Tutorial

A simple, clearly written tutorial on the diffusion equation that takes us from Brownian Motion to Fick’s first law.
​

Biollante

 

[Gerryd]

Hi Bio,

As I thought, this will be over my head

But, I thought Tom speculated that the mist ITSELF helped break the boundary layers on the plants themselves and that is what made the 'improvement'. Not necessarily that misting diffused c02 into water more efficiently.

In any event, I must do the required reading you provided to get up to speed.

At my intelligence level, it may be months before I respond lol

As always, I appreciate the dialog and a chance to learn.....

I look forward to the ensuing discussion...

 

[Biollante]

Distinction Without A Difference

Hi Gerry,

I fully accept that Tom Barr speculated the mist breaks the Prantl boundary layer. This is a distinction without a difference in my ever-humble potted-plant opinion.

The object is to get plant friendly nutrients, in this case carbon dioxide, into the plants. Does the extra expenditure of carbon dioxide provide better, more efficient plant growth? I am willing to accept whatever the most effective (best?), efficient method the average hobbyist can employ. :gw

I cannot find the evidence that it provides any more than a marginal benefit over other in aquarium “diffuser” method. Was I the churlish sort, I would demand a falsifiable hypothesis, before I would even entertain them. Given the number of variables, I think coming up with a falsifiable hypothesis difficult at best. As with many complex systems, we will probably have to content ourselves with probability.

Even should it turn out that “misting” was superior it is hard for me to imagine getting over the carbon dioxide waste issue, unless the difference was overwhelming.

I actually believe the greatest damage this speculation causes is the misunderstanding of the role of dissolved gasses, circulation and diffusion in the Fick’s First Law or Brownian motion sense of the word.

Gerry, you are one of the most thoughtful, intelligent people I know.

Biollante

 

[fjf888]

Seems like I hit upon something here.

I appreciate all the replies.

I come from a hobbyist, non scientist, lowly educated, approach. My understanding was that misting essentially was thought to be the approximate equivalent of emersed CO2 in a submersed system. I know my floating riccia goes from an golf ball size to a softball size in a matter of a week.

I work on the complexities of tax law and I would need a bunch of time to dissolve everything in my brain related to the actual science behind this.

Perhaps with my reef tank pre-drill as opposed to the way Tom pre-drills his tanks with sump it may not make sense for me to use this method. Maybe the better answer is to use a reactor with a separate pump in the sump or external pump powering a reactor with inflow at middepth, keep the surface chop with the main pump. I was running the reactor through the main pump before.

Ironically I actually moved my lighting forward a few weeks ago to try to get more light onto the foreground, moving it back should solve the GDA problem. I also trimmed and replanted to help improve flow throughout the tank. I think the BBA that occured possibly was less of an overall CO2 issue and maybe a CO2 dispersal issue.

 

[Biollante]

Bingo! As "They" Do Say

Hi Fred,

I think you are correct in your view of misting, I also wish to be clear, misting works. Misting is an effective, proven method of providing carbon dioxide to aquatic plants. For floating plants or broad leaf plants higher up, it is a shotgun approach.

I think Dutchy added the concept of efficiency.

The object is to find the “thing” that works best for the most people as cost effectively as possible. :gw

I am in no way opposed to anyone choosing misting as a way of introducing carbon dioxide to their aquarium.

While I do not think misting is the ultimate answer, at least it moved the hobby away from the wastewater treatment model the expensive Japanese guy sells. That model hobbyists start with the “aquarium as reactor,” diffusers, seem effective when used at a depth of more than 10 feet (3 meters) with flow rates in excess of 3 feet (1 meter) per minute.

Biollante

 

[scottward]

Biollante - the links you posted above don't seem to work - I'd like to read the "Methods of delivery of Carbon dioxide (CO2) for submersed aquatic macrophyte fertilization: considerations for adding CO2 gas phase mist" Barr Report - but cannot find it even under the Barr Reports grouping (I am a subscriber).

 

[Biollante]

How Did I mess That Up?

Hi Scott,

Thank you for the heads up, I am not sure how I messed up the links, but I did.

Below are the corrected, I hope, links.

Since the first, four require subscriptions it may be that another thread be created in the subscriber’s area.

http://www.barrreport.com/showthread.php/1095-Barr-Report-Newsletter-CO2
Methods of delivery of Carbon dioxide (CO2) for submersed aquatic macrophyte fertilization: considerations for adding CO2 gas phase mist
This is the basic text and I think an area that set the stage for further exploration.
“The bubbles.” I think this is where I get in trouble.

http://www.barrreport.com/showthread.php/535-Barr-Report-Newsletter-Carbon
Dissolved Inorganic Carbon (DIC)
A tough read, perhaps a little overly condensed.

http://www.barrreport.com/showthread.php/703-Barr-Report-Newsletter-Carbon
Dissolved, Particulate and Microbial Biomass Organic Carbon (DOC, MBC, and POC)
Good straightforward explanations.

http://www.barrreport.com/showthread.php/1678-Barr-Report-Newsletter-Oxygen
Oxygen in the Planted Aquarium
Straight forward explanation of Fick’s First Law

http://www.rpgroup.caltech.edu/~nats.../diffusion.pdf
The Diffusion Equation, A Multi-dimensional Tutorial
A simple, clearly written tutorial on the diffusion equation that takes us from Brownian Motion to Fick’s first law.

Biollante

 

[scottward]

Biollante - Cool - the links are working now - thanks.

Regarding the whole reactor vs misting thing, one thing that still confuses me and I don't think anybody has explained it clearly enough yet (or I just haven't stumbled across the text), is why all the tiny bubbles of CO2 are actually visible in the first place and why they don't just dissolve out of site? I could understand why the bubbles wouldn't disolve if the water was already saturated with CO2 (in the same way that salt crystals sediment in a glass of water that is already saturated with salt), but the water isn't already saturated (the fish are still alive!).

If the bubbles disolved out of site by the misting technique, then I suppose, as Biollante was mentioning, whether the bubbles are disolved in an external reactor (e.g. AM1000) or the tank itself (where by the tank is essentially the reactor itself) the end result will be exactly the same?

I currently use an AM1000, but, also bleed part of my CO2 into a powerhead connected to a spray bar that mists the gas directly into the parts of the tank where the plants are the thickest.

Scott.

 

[Biollante]

What Happened To My Rock Salt Substrate Cap? It Was So Cool!

Hi All,

I suspect you are having the same problem in understanding we all have.

Part of the problem is that there is no definitive understanding that is why we speculate!

The question of CO2 gas dissolving is a very good question, one you have asked several times and at the heart of the issue. I am not sure I have the best answer.

Let me extend your salt analogy, it a good one.

• Rock salt crystals are analogous to CO2 bubbles, the larger the crystal the longer it takes to dissolve. A handful of rock salt crystals will take longer to dissolve if dumped in a pile as opposed to the same quantity spread out evenly.

• As with the rock salt crystals the better stirring (another word for circulation), the better the separation hence the quicker the salt goes into solution.

• Salt and CO2 in solution are heavier than freshwater

• To complete the analogy let us assume that when the salt hits the bottom of the tank we remove them, here the better the circulation the longer the crystals have to give up mass to the water (solvent).

CO2 is less soluble than rock salt NaCl and being a gas has to obey a couple of other laws as well. The analogy has to be strained. My understanding is that CO2 bubbles 25 microns and smaller are the principle actors. 25 microns is smaller than the unaided eye can see.

I think the other problem is terminology, in one sense of the word, diffusion includes spreading bubbles around the tank; it simply is not the diffusion of solutes.

I have more if anyone is interested.

Biollante

 

[scottward]

I suppose the answer then is to get the bubbles as small as possible - so misting (via disk, mazzei) etc is always going to win? Why have I heard that misting is wastefull? If it's producing the smallest bubbles, which should therefore dissolve best, how could it be wastefull?

Scott.