CO2 revelations

[plantbrain]

CO2 is one of those critical things that aquatic plants folks should really focus on.
I've nagged folks about this for a very long time, and I will likely nag you to the grave.
Complacent experts, newbies, test kit freaks, all of you(and myself included).
Poor CO2 reduces growth and is responsible for nearly 95% of all algae related issues.

Now KH test kit variance is one issue, making a reference standard to compare you KH test to is a very WISE idea to check the accuracy. I've seen many folks have very high CO2 predicted levels, yet fish were fine, but another than has barely 30ppm and the fish are gasping. It cannot be that both are at the same CO2ppm level becaused we would expect to see the same behavior from the fish. Instead we see very wide ranges and impacts on the fish(as well as plants).

So it's much more likely that it is the testing method, rather than anything else.
pH is the best thing as far as accuracy for CO2 measurements using a pH probe and no electrical equipment runnign when the pH is measured(stray current will depress the pH giving false high ppm CO2 levels).

KH test kits have consistency issues (see recent post) and in some places, although rare, non bicarbonate alkalinity exists(recent poster in NM has significant borate alkalinity, desert regions generally).

Addressing this issue by making a reference sample will take care of the KH issue.

The next issue is more interesting for many of of you.
I'd suggested that the venturi DIY reactor I have shown folks on my site is better than any reactor. Well, initially, and perhaps partially true, is the purpging effect of gas build up.
This gas is some O2 and some CO2, but very little "air".

As the gas is expelled, consistently I see better growth, this is not due to O2.
So why would a mist of tiny CO2 bubbles vs dissolved CO2 in solution do better for growing plants?

I addressed the O2 issue simply, I used a diffuser disk for CO2(no O2 gas build up occurs).
But that did not do it __alone__.

I wondered why.

So I placed the diffuser disc near similar current like that produced by the venturi reactor after is starts mistuing the gas out the bottom.

Lo and behold, Bam! Excellent similar growth.
Not the kind of so so growth, but pearling like nothing you have ever seen or perhaps only in a very few well run tanks right after a water change. But I'd not done a water change for a week.
I tried it several times on 4 tanks, same result in each tank. Day after day, intense pearling even with fair good current.

So why would this mist be better than dissolved CO2?

For one thing, it's __pure CO2 gas__, which flows much faster than dissolved CO2 liquid.
The flux rate is much faster with pure CO2 gas than CO2 dissolved in water, so the plants get more CO2 and a more concentrated form.

Some folks may not like the bubbles, some might not like pearling.
But I sure do.

I can say that the venturi effect is one of CO2 now, and not of O2 by using the diffuser disc to rule out O2.

So that just left CO2 and the gas vs dissolved form to consider why one method was better in terms of plant than another.

Both flow and actually having some gas in the tank itself seems to be the key here.
So those disc are not so bad and neither are the venturi reactors.

You can make a purge loop for external reactors by making a hole 1/2 down and running the air line back to the intake for the power head, caniter filter etc, this will not add bubbles but will reduce the gas build up inside the reactor.

The real issue is having gas bubbles in the tank and putting them where the plants are in that form.

I think folks should really consider this/these idea/s and try them.
I've had very intense pearling and have over the entire routine time frame, not just for a day or a few days.

Be careful and watch the fish, CO2 levels when doing this, I've not had any fish issues yet. Make sure there is some surface movement. If you use disc, clean them often(monthly).

For larger tanks, they make 6x1" diffuser stones for about 60$ than can be used set along the bottom back gravel layer so they will not be seen. wwww.aquaticeco.com sells them if interested.

In any event, this notion of having tiny gas bubbles floating around very dissolved CO2 might solve many folk's problems and improve those who seek better growth.

Nitrogen is an essential element, but only 1.5%, vs 40+ % for Carbon, it is very very wise to focus on this if you seek better growth.

With good CO2 levels, even the wimpy plants do very well(Tonia, ES, Eirocauleon) algae dies, pearling as intense as you have ever seen it day after day will occur.

I think the gas bubbles might also be less of an issue for fish since it's not dissolved into solution also.

The nutrients can be addressed easily by doing EI, so you know there's enough, so all that's left to really focus on is the CO2.

So I have been playing around trying to figuire out a good way to reproduce max CO2 without causing issues for fish, and adding enough for the plants.

The CO2 mist + current seems to be the best method.

This can be done with a reactor or a diffuser stone/disc.

Also, folks using spray bars, turn them vertically, next to the intake and place the disc down near this also. This hides the bar, the disc, intake all in one place. Having the spray bar current blowing along the back side the tank wall seems to give good flow characteristics+ near the disc, the water blows out and away from the intake and circles around to the intake.
Since water is being blown directly away from the intake, this gives optimum mixing.
Since water is being blown directly on top of the difusser, all the bubble mist is being blown all over the tank.

The results are easy to see.

The other issue is not to trust the test kits so much until you see the type of pearling like this, no BBA growth etc, slowly and patiently add more CO2 till you get the pearling and good growth. Basically use the test to get close, then tweak(add more) carefully and slowly.
Do not go overboard, do it slowly and observe the plants/fish. Your test may give you high numbers, but if the fish are fine, then it's okay.
Turing off CO2 at night will help add the margin of safety also. We add CO2 for the plants, not to maintain pH. Some leave it 24/7, but mainly out of convenience rather than methodology. With disc, running them at night can cause issues, anyway, you can save 2-3x the gas by not running it at night. We know fish don't care about the pH change.


Regards,
Tom Barr

www.BarrReport.com

[Georgiadawgger]

Good stuff Tom.

I was wondering how well the little disk diffusers worked. I may have to try one someday.

[Jason Baliban]

What questions are being addressed here?

Are you saying that dissolved CO2 is less "available" to weeds? Thus stating that CO2 that is not fully dissolved CO2 is actually more beneficial?

Wouldnt this make the PH/KH relationship even less reliable. These floating bubbles in the tank effect PH or do not effect PH?

I'm not sure what exaclty we are uncovering here? Are we talking about CO2 effeciency as far as administering or beneficial as far as plant usage?

Thanks

jB

[Robert H]

I guess you have to go to his WEB site. I didn't understand 80% of what he wrote here, did you? I have so many tanks in my shop that I have the C02 connected to power heads that just blow it out into the water, into the path of a filter out take. According to what Tom has said here this is actually better than a reactor and I should be getting super growth and pearling????

Thats not the case at all for me. I only do this because it is a lot cheaper than setting up reactors, but I do not get tremendously fast growth or rapid pearling. These aren't display tanks and have no fish. In the past I have used ceramic disk diffusors, Eheims, and it was a total waist of time. It was much more difficult to reach 30ppm and hold it there consistently than when I used a reactor. Tom used to make reactors. I used to sell his reactors. Once you figured out how to put them together they worked great. In fact I think it was he and his reactor that converted me from the inefficient Eheim diffusor. Now we are taking a step back? I don't get it.

[shalu]

Tom, apart from "pearling", have you compared actual plant growth in terms of inches/week?

In my non-CO2 tanks, I have been supplying AIR into the HOB filter via an air pump. The filter spits out a mist of tiny air bubble(a small percent of that is CO2, of course) in the output flow. I would see a lot of "pearling" on my plants, and I never thought it could be real pearling and assumed that those were tiny air bubbles collected under the leaves and formed bigger bubbles.

[malkore]

Originally Posted by shalu

Tom, apart from "pearling", have you compared actual plant growth in terms of inches/week?

In my non-CO2 tanks, I have been supplying AIR into the HOB filter via an air pump. The filter spits out a mist of tiny air bubble(a small percent of that is CO2, of course) in the output flow. I would see a lot of "pearling" on my plants, and I never thought it could be real pearling and assumed that those were tiny air bubbles collected under the leaves and formed bigger bubbles.

You are increasing oxygen artificially by injecting air into the HOB...thus you reach O2 saturation more easily, so the plants pearl almost effortlessly.

[Georgiadawgger]

Originally Posted by shalu

Tom, apart from "pearling", have you compared actual plant growth in terms of inches/week?

In my non-CO2 tanks, I have been supplying AIR into the HOB filter via an air pump. The filter spits out a mist of tiny air bubble(a small percent of that is CO2, of course) in the output flow. I would see a lot of "pearling" on my plants, and I never thought it could be real pearling and assumed that those were tiny air bubbles collected under the leaves and formed bigger bubbles.

That could be the case too...hummm

As far as the co2 gas being better in bubble form vs. dissolved in water, that is a puzzling aspect. Wouldnt submerged plants benefit better from the gas exchange in the medium they are growing in?

One of the interesting things I've noticed about external reactor is the excess gas buildup inside that is part co2 part o2 that sucked in by the filter/pump via intake. I had this issue running my external reactor that was made from 1 1/2 inch tubing (15 inches long) attached to my 2224. Once I upgraded both reactor (to 2 inch diameter, same length) and attached it to my 2026, I never get a huge gas buildup inside the reactor.

Two modifications I've made: 1. a venturi valve at the top of the reactor with an airline that goes into the tank. I got tired of flipping the reactor upside down every time I cleaned my filter (the air gap in the hoses surges into the reactor); which was also built to purge excess air from the reactor in the evening. 2. put the input from the filter on the top-side of the reactor rather than top-down...this swirling action seems to dissolve co2 quicker.

[shalu]

If Tom's theory about CO2 bubble (100%) being far better than dissolved Co2(30ppm) is right, then perhaps indeed aeration alone helps quite a bit with plant growth. After all, air has 0.033% Co2 by volume, which converts to 502 ppm by weight, still far higher than our CO2 concentration in water.

When I started aerating my non-CO2 tanks, I was only thinking about keeping CO2 level at least at equilibrium level in water: about 2 ppm. Maybe I am getting the unexpected benefit of those tiny bubbles. By the way, don't try connecting those CO2 diffuser discs to air pumps. The higher pressure from air pump builds up and destroys the disc in a second. Wasted my $15 diffuser.

[plantbrain]

Originally Posted by Jason Baliban

What questions are being addressed here?
Are you saying that dissolved CO2 is less "available" to weeds? Thus stating that CO2 that is not fully dissolved CO2 is actually more beneficial?

I am suggesting in this particular case

Wouldnt this make the PH/KH relationship even less reliable. These floating bubbles in the tank effect PH or do not effect PH?

Yes.

I'm not sure what exaclty we are uncovering here? Are we talking about CO2 effeciency as far as administering or beneficial as far as plant usage?

Thanks

jB

I'm saying the delivery is the issue here and the form of the CO2(gas or dissolved in water).

Which do you think would improve growth faster?
1. Gas pure 100% CO2?
2. 30ppm is thick visicous water?

The concenration and the diffusion rate of gas is much higher on both counts.

pH/KH issue: if the bubbles are still gas and not yet dissolved(they can be asorbed by plants before hand or bubble out the top of the tank etc) then this will make the tank appear to have lower CO2 ppm wise based on the chart.

We recently added a venturi to a reactor design on a 180 gal tank here in SF, nothing was changed other than this loop. The result was a an increase in pearling by about 2-3 hours eariler. pH decline of 0.3.

This difference in growth is large enough to warrant serious consideration. It is significant, more so than little trace dosings, miracle joices and what have you.

Does not matter when you do a water change.
I have been using diffuser disc for some time on all but one of my personal tanks that have CO2 added.

Some minor changes like this have greatly improved the health. The reactors
are good if they produce a mist.

This at first seemed counter productive, it wasted gas after enough of a CO2 bubble formed the last 1/2 of the day.

But that is when pearlign really kicked in.

So I added lots of CO2 right away to produce misting right as the lights came on and continued.

The results were the same as when I use the diffuser stone and current.

Placing the diffuser stones in the current, keeping them clean will great improve things if done properly.

I've use diffuser disc off and on over the last 10 or so years.

But now I fully understand the potential use of these as well as the venturi reactor and why both radically different methods work similarly.

Think about it like this, even at 3% CO2 in the air, plants grow faster in emergent set ups.

Adding 100% CO2 will improve plant growth terrestrially as well.
So the same should hold true for submersed growth also.

Robert makes a good point:

According to what Tom has said here this is actually better than a reactor and I should be getting super growth and pearling????

Well a normal reactor, not with the venturi.

Thats not the case at all for me. I only do this because it is a lot cheaper than setting up reactors, but I do not get tremendously fast growth or rapid pearling.

You need consistent small tiny bubbles and to move them through the plant beds as evenly as you can.

These aren't display tanks and have no fish. In the past I have used ceramic disk diffusors, Eheims, and it was a total waist of time. It was much more difficult to reach 30ppm and hold it there consistently than when I used a reactor.

Yes, many felt this way but many here in SF also used them quite well(they killed their fish but that was due to a lack of a needle valve, those with the valves did very well).

Reflecting back and using them like the venturi reactor instead of passively increased the plant growth and measuring the CO2 was no longer even really needed in terms of pH/KH. Steve Dixton used his Ehiems very successfully this way, so has Jeff and other folks.

Tom used to make reactors. I used to sell his reactors. Once you figured out how to put them together they worked great. In fact I think it was he and his reactor that converted me from the inefficient Eheim diffusor. Now we are taking a step back? I don't get it.

Actually, getting a handle on a few things, we might be able to target excellent CO2 levels with less issues to fish/higher CO2 for the plants, and easier methods to do it.

Even if the test are little off(which very often they are).

Regards,
Tom Barr

www.BarrReport.com

[plantbrain]

Originally Posted by shalu

If Tom's theory about CO2 bubble (100%) being far better than dissolved Co2(30ppm) is right, then perhaps indeed aeration alone helps quite a bit with plant growth. After all, air has 0.033% Co2 by volume, which converts to 502 ppm by weight, still far higher than our CO2 concentration in water.

When I started aerating my non-CO2 tanks, I was only thinking about keeping CO2 level at least at equilibrium level in water: about 2 ppm. Maybe I am getting the unexpected benefit of those tiny bubbles. By the way, don't try connecting those CO2 diffuser discs to air pumps. The higher pressure from air pump builds up and destroys the disc in a second. Wasted my $15 diffuser.

If you use pure O2 and regulator it works well

Is 0.033% going to grow plants better or is 100% going to grow plants better?
Both are gas phases.
30ppm will work mind you, and can do quite well.
But this is definitely better, which is the revelation part.

I'm talking every odd wimpy plant species you can think of.
Suddenly growing and pearling like no tomorrow with only this one change.


Aeration adds enough CO2 for marine plants BTW, I'd like to try a non CO2 aeration tank, but as Sha lu found out, the diffuser did not work well.

I'd like to get a compressed air tank instead of the pure O2 and see if this would do well for the non CO2 method..............ah that would be cool.

The key here is bubble size, it needs to be very fine.
I know folks have tried vigorously aerating and in certain part of the tank you can see good results from this, but at higher levels of finer aeration, I wonder if this could be improved.

If so, that would be a radical change, no CO2, no CO2 dosing , no CO2 fish kills and better growth than non CO2 etc.

Dissolving O2 is not the goal, getting the bubbles very small and onto the plant leaves is the goal.

Regards,
Tom Barr

www.BarrReport.com

[shalu]

I first did the aeration on my 10 gallon shrimp tank. I treat it like a low tech tank and dose it as such: very little, that is. My initial goal of aeration was two folds: 1) enough O2 at all times for sensitive shrimps. 2) some CO2 in water at all times during photoperiod. I don't like the large bubbles from the air stone directly, so I feed the air stone into the HOB filter intake. The bubbles were broken by filter impeller and lots of tiny bubbles were mixed in the filter output. I got exactly what I wanted, and then some. I got surprisingly fast growth from couple of weeds: najas and lagarasiphon madagascariensis. Granted, those are easy plants, but the growth rate was astonishing. I have to prune them every few days, not weeks. In the mean time, I see deficiencies developing in other plants(pale, smaller growth etc). Those same plants used to provide slow, but steady and lush growth. It is obvious now that I am really underdosing. What used to be enough is no longer enough.

[Hypancistrus]

That could be one of the reasons Amano's tanks do so well... he uses CO2 "micro bubblers" as diffusers.

You can buy them for a realistic price here --> http://www.aquabuys.com/miva/merchan...roduct_Count=1.

[rrguymon]

Originally Posted by plantbrain

You can make a purge loop for external reactors by making a hole 1/2 down and running the air line back to the intake for the power head, caniter filter etc, this will not add bubbles but will reduce the gas build up inside the reactor.

Regards,
Tom Barr

www.BarrReport.com

I am not sure I follow this. Unless you are saying you need two pumps. If run the gasses that are in the reactor back to the intake of my canister filter won't the gases just keep taking the scenic route through my filter to the reactor and back over and over again?

It would make more sense to me to run the gas over fill tube to a totally separate pump or power head. That would really get it out of the filter loop. It might even work if you just routed it down stream of the reactor in the output side of the canister. You might get a venurti effect that would draw it out or you might just pump the same water through the reactor over and over again.

Thanks

Rick

[Tino]

Tom,
completely, wholeheartedly agree on the effectiveness of ceramic disc diffusers, had similar successful experience myself, and look at Amano and Oliver Knott's tanks - it was their #1 choise all along!

[stcyrwm]

This is too cool. I've got a compressed air tank. What else would I need???? Something to regulate pressure but it would start lower than a CO2 tank so this could be much simpler and cheaper. Then feed it into diffuser by powerhead and we're off and running. Any thoughts? Refills by my own compressor or bring it to the gas station - lol...........

I'm going to try this tomorrow.........

Bill

Originally Posted by plantbrain

If you use pure O2 and regulator it works well

I'd like to get a compressed air tank instead of the pure O2 and see if this would do well for the non CO2 method..............ah that would be cool.

The key here is bubble size, it needs to be very fine.
I know folks have tried vigorously aerating and in certain part of the tank you can see good results from this, but at higher levels of finer aeration, I wonder if this could be improved.

If so, that would be a radical change, no CO2, no CO2 dosing , no CO2 fish kills and better growth than non CO2 etc.

Dissolving O2 is not the goal, getting the bubbles very small and onto the plant leaves is the goal.

Regards,
Tom Barr

www.BarrReport.com