How Does an External CO2 Reactor Work? (e.g., Dupla, AquaMedic)

[DTs]

I have the large external Dupla CO2 reactor with the bioballs in it and was wondering how it works.

The instructions don't say much other than it should be completely filled with water when working correctly.

My guess is that as CO2 bubbles are injected from the top of the unit, the water flowing down the unit keeps it suspended and it bumps into all the bioballs, helping it to dissolve better in the water.

Is this correct?

One thing I haven't figured out yet is if I flood the entire chamber with CO2, forcing the water to exit the unit, and then turn the CO2 off, and subsquently increase the water flow to the reactor chamber, it fills up again with water within seconds, but where does the CO2 go? It certainly is not going back out to the tank, or I would see bubbles coming out. It's almost as if there's a venting valve somewhere letting it escape.

[bobalston]

In the situation you mention, it would seem that the co2 is getting disolved. There ain't no other place for it to go.

Bob

[DTs]

My thoughts exactly, but believe me, it's not dissolving that fast! The entire chamber of CO2 evacuates in about 10 seconds.

The CO2 has to be venting somewhere. When I get home from work, maybe I'll stick the whole chamber in a bucket of water and repeat the CO2 filling/evacuation process, and see if venting occurs.

[plantbrain]

CO2 dissolves very fast, especially if the water doesn't have much in it.

Example: you can watch a CO2 bubble(1/16" dia) disappear as it floats up say 20" depth. That takes a few seconds.

Regards,
Tom Barr

[DTs]

Could about 1,000 bubbles be absorbed into the water from a reaction chamber, say in 10 seconds? :D

FWIW, my dKH is 4 (Salifert test kit), temperature is 78, and pH 7.1.-7.2

[carpguy]

You're filling the entire chamber with gas and forcing all the water out? That's definitely not how they work…

You can then fill the chamber with water in ten seconds without having the gas forced into the outlet? Even if you had a significant leak a lot of the gas should be bubbling out the return…

A thousand bubbles all at once aren't going to even think about fully dissolving in ten seconds. Most of us are bubbling 1 or 2 times per second. Maybe 3. Not a hundred.

The water bucket is a good way to check for leaks, but I still feel like I'm missing something…

[DTs]

Just filling the chamber with gas as an experiment. I run it normally with the chamber full of water.

Gas bubbles should be forced out into the tank when I fill it with water, however none are coming out. This must mean there's a gas leak/venting going on somewhere. Need to figure out where though.

[plantbrain]

Well try it and see, I have used reactors and often they fill in the evening, then the Reactors are shut off at night and then they dissolve away rapidly within a few minutes/seconds when they are turned on in the morning.
Your water is seriously low in CO2 also.

So yes..........I am right or you have a leak.

To rule out a leak:
If you have a leak, there's sure to be some water on the floor when they are full is this not true? Since water fills it and where water can go, so can gas.

Especially if the reactor releases all that gas in 10 seconds.

To check further for a leak, use some soapy water, and dribble some over any region you believe is leaking.
If it's leaking, you'll see bubbles.
And then perhaps we will see if I was right or not. :)

Regards,
Tom Barr

[DTs]

Plantbrain - I totally agree with your comments!

Something has got to be wrong with my reactor, or either I'm doing something very wrong. If I turn the CO2 off most of the day, my CO2 is 7.2. If I turn it on at 4 bubbles a second for a newly planted 90g tank (e.g., no major growth going on yet), my pH is 7.2. This tells me that CO2 is not dissolving in the water to any great degree.

The reactor instructions mention that if there is any air in the chamber when starting it up, to invert it, and the air will discharge. I thought perhaps I'm running the reactor upside down, but according to the illustrations, I'm doing it correctly.

I still need to put the reactor in a bucket of water and see where the gas is venting. Didn't have time last night. I'll give it a shot tonight.

[plantbrain]

No bucket needed, just put some soapy water on it now and see.

That will tell you if you hasve a leak somewhere, simply wipe off later.

Should only take 5 minutes tops.

Regards,
Tom Barr

[DTs]

Thanks again, will work up some suds tonight.

You'd think it wouldn't be difficult to find out where a large volume of CO2 gas is going in about 5 seconds!

To make matters worse, the ballast to my brand new Giesemann 150w Nova II pendant is heating up so much that it's actually hotter than the light fixture itself with the bulb on. Giesemann is sending a new ballast as they said this is definitely not normal.

[plantbrain]

I had one burn up and cause a fire in a client's home about 10 years ago.
They replaced it but it took a long time.

Other than that, I like them:)

But I prefer electronic ballast, HQI double ended(I think the Nova's are that type) bulbs and small fixtures.

You spent a big chunk on equipment I can tell.

The DIY reactor shown at Ghori's site is based off my old design which is somewhat based off the Dupla, but this cost about 10$ to make.

Regards,
Tom Barr

[DTs]

Giesemann does make beautiful lights, and they provide exceptional service. Yes, I have spent a chunk on equipment, but reefkeeping has taught me to buy what I feel will work best, regardless of cost.

Obviously you don't need to spend a lot of money to have a thriving system, but it helps not to skimp on things like lighting.

I'll check out the DIY reactor. Thanks.

[DTs]

Ok, I did the experiment tonight. I didn't want to leave any doubt in my mind so I immersed the entire Dupla reactor in a bucket of water, cranked up the CO2 to fill the entire chamber, shut off the CO2 once the chamber was filled, and then let the filter water run through the chamber.

The chamber did it's usual "filling up with water very quickly" routine. Result... no leaks in the reactor or CO2 line. I simply can not believe all that CO2 was forced into the water that quickly, but that must be what's happening, because absolutely no gas bubbles went back to the tank or filter lines to the reactor.

I guess the reactor's doing its job!

[plantbrain]

The bioballs thingys help dissolve it faster.

Now add enough CO2 to your tank to get a pH of 6.6 to 6.7 and keep it there while the lights are on.

Then you are done with CO2 except for the ocassional check or if anything seems wrong(Always check CO2 first, then........other issues).

Regards,
Tom Barr

[DIYMatt]

When I had a reactor with bioballs and a mesh screen hooked to the input side of a canister filter and upped the CO2 to produce a burst of CO2, quite a lot of it went down into the canister and dissolved there. Now, my reactor is on the output side and if I produce a burst of CO2, some comes out the output of the filter. It doesn't really matter, its getting dissolved and thats what matters. Just my two cents on the reactor question....

[DTs]

I'd love the pH to be 6.7 or 6.8. I'm adding 2 bubbles per second right now to stay at 7.1, so I'm probably going to to crank it up to at least 4-6 bubbles per second for now. Since I have a pH controller, I could simply keep it at 8 bubbles per second until it hits the target pH and turns off.

Thanks for hanging in with this thread Tom. Although I have over a decade of intense reef experience, plants are a new game for me, although many aspects are similar.

I'm just surprised at how much CO2 it takes to get the pH down. I supposed the fact that my tank is new and doesn't have much organic matter probably helps keep the pH up.

[DTs]

Mission accomplished. pH is now holding steady at 6.8 via the controller.

My tank is a week old as of today and the plants are growing nicely. I have a baby tears plant that's sending shoots off to the sides so perhaps I'll use that as a foreground carpet. It really seems to be happy in my tank. I also have true micro e. tennellus, but it doesn't seem to be very happy. I'm trying to figure out if it's just still recovering from shipping, or if it doesn't like my halide lighting.

[DIYMatt]

The E. tennelus in my tank seems to like my Halides. It grows very dense, but strangely seems to spread faster in my PC lit tank. What color temp/type halides do you use? I use cheapie 4000K bulbs.

[plantbrain]

As long as you maintain the CO2 way up, much likme the Ca++ and Alkalinity in the coral reef/marine planted tanks, you'll do fine.

The nutrients are cheap and the water changes are easy.

www.litemanu.com

For
KNO3
K2SO4
KH2PO4
Traces

These plus water changes makes the tank really do very well.

I'd do a lot of 50% water changes for the first few weeks, maybe 1-2x aweek.

Afterwards, add the KNO3, K2SO4, KH2PO4, and trace back.

This way you can keep the nutrients in a good range for the plants.

It's like making a reference solution each time you do a water change.

It prevents anything from building up, and also prevents anything from running out.

It's also easier than testing more than one item.

And it most cases it's more accurate.

Example routine for a 20 gal with high light/CO2

1/4 teaspoon of KNO3 3x a week
1/4 teaspoon K2SO4 once a week after water change
2 rice grain's worth of KH2PO4 3x a week
5mls of trace mix 3x a week.

50% weekly water change

You scale this up/down to where your tank size is.

You do this, the plants will grow very very well.

If you want to start up a tank well, use Flourite etc, add some mulm from the old tank, or the LFS,a friend's tank etc.
That's the stuff that settles in the bottom of the water after vacuuming.

Add a liter or two wet to every sq ft of tank floor space.

Add a handful of ground peat to each sq ft also.
Top with Flourite.

That, along with good CO2 will make a tank do very well.

Regards,
Tom Barr

PS if you like plants, try marine plants.


See my thread on that here.

[DTs]

I use 150w 6000k halide (Giesemann bulb).

I'm thinking perhaps I wasn't dosing enough CO2. I'm not sure how much tenellus needs, but it has plenty now. It could just be that some of the leaves have browned due to transportation, etc. I didn't get much of it, only about 12 or 13 tiny "sprigs", and it sat out for a day in a saucer of water while I tried to figure out if I was going to use it, or glosso., for my foreground.

Separately, I added 15 little Amano-like shrimp and 4 true SAEs, to begin the critter population. After a few weeks, I'll probably add a school of cardinals or rummy nose tetras, and a few Altum angels.

[emoore]

When I first planted my E. tenellus the leaves turned brown and I thought it was going to die. That lasted for 2-3 weeks. Then it started growing well. Now I have to trim it every week to keep it from taking over the slower growing plants. Give it some time and I'm sure it will do well.

[DTs]

Once again, hearty thanks Tpm!

You actually answered a question I've been wondering about -- how to add trace elements. I read that most professionals add them separately based upon the traits exhibited by the plants.

I did a 50% water change yesterday, and will continue to do so, and possibly 2x, as time allows.

My substrate is as follows: about 3/4" of Fertiplant:
http://www.floridadriftwood.com/product.asp?0=242&1=255&3=767

and 3/4" of Fertiplant Plus: http://www.floridadriftwood.com/product.asp?0=242&1=255&3=768

and 3"-5" (tank front to back) of Eco-Complete substrate (120 lbs). This stuff comes wet with all the bacteria needed to rapid cycle the tank. Supposedly you can add fish right away, but my primary concern of course is to get the plants growing strongly to avoid algae issues, before adding my fish population.

I don't know if I mentioned it, but I have a 90g SPS reef tank. I only have chaeto. in the refugium. I'm on Reef Central (DT's_Reef).

[DTs]

Tom, very cool marine tank. I've never seen so many plants species in one tank. Nice use of color too.

You must have a million pods in that tank! A mandarin goby would think it went to heaven.

[DTs]

Tom,

I'm placing an order with www.litemanu.com and want to be sure I'm ordering the right stuff.

KNO3 = Potassium Nitrate?
K2SO4 = Potassium Sulfate?
KH2PO4 = Potassium Phosphate Monobasic?

What trace brand would you recommend? Thanks

[Jeremy S]

DTs, this calculator (http://www.csd.net/~cgadd/aqua/art_plant_aquacalc.htm) helps a lot when you go to add the ferts to your tank.


http://www.csd.net/~cgadd/aqua/art_plant_aquacalc.htm

[DTs]

Thanks Jeremy. I installed it to my desktop.

[plantbrain]

That fert substrate is over priced, well so is the Dupla stuff generally.

Most plant folks here had serious cost back lash towards them.


And that substrate I suggests, has all the bacteria that an established tank has and you are not paying for water.
The long term german shcmerman stuff, I'd not put that in there, the Eco compete etc claims all sorts of funny business and so do these others.

If it has a porous hard iron rich clay grain, then it's good. Beyond that, adding trhe mulm and peat is about all you'd even need to add for any substrate.

Basically: you'll get a lot better results, and you'll be much more able to control these results with dosing of the water column vs the substrate. You can test and change the water column, cannot do that with the substrate.

The main purpose nutrient wise for ther sub is another source of iron beside the water column.

You can and should add algae eating fish asap, I add my fish that same day with the mulm method.

They will nibble the algae before it gets started. Add only algae eaters for the first 12 months, then add the main after the tank has settled in well.


Amano shrimps are particularly useful. You can get a deal on 100 at most LFS for about 50-80$.
These are the best algae eater but you need enough of them to do the work, don't expect much out of 6 in a 90 gal tank.

Regards,
Tom Barr

Regards,
Tom Barr

[SnakeIce]

pH is now holding steady at 6.8 via the controller.

is this controller part of the co2 system? or is this a optional addition to that system?

what it does sounds cool... can you point me to a product description or some thing like that?

[DTs]

Tom, I was fortunate to get a 40% discount off the Dupla stuff. Even at that it's still very expensive. Dupla was bought by Red Sea who is redesigning all their products. Hopefully the quality won't go out the window. I was lucky to get a substrate cable heater system (40% off too).

I added 4 true SAEs yesterday, along with 15 shrimp. I'm sure I could do with another 30 or so, but didn't know what to expect so I was conservative. The SAEs are going to town on the plants. I don't have any algae that I can see, but I'm sure it's somewhere.

So, no other fish for 12 *months*?

SnakeIce -- a pH Controller (Milwaukee makes the cheapest quality unit, about $85-$90) works in conjunction with the solenoid on your CO2 regulator in that it basically turns your CO2 on and off in order to keep the tank water at a pH level that you dial into the controller (e.g., 6.8). It'll maintain your tank at that value all day, so it adds a nice measure of stability to your system. All you do is have to search for "pH controller" on the web and you'll get a lot of web hits.

[plantbrain]

I add the main fish 1-2 months, I'd never wait 12 months.

40% of stuff that's over price is no deal.
The cables you certainly did not need.

I have had full blown Dupla/Tunze systems for clients.
We sold off everything years ago. Got 300$ for the cables:)
The clients have had planted tanks now for 10 years, we replaced the sand/cables with Flourite and all's been better over the long term.

I know they(cables) don't do anything and are waste of $. They don't hurt, but they don't help either.

I have 3 ex clients that attest to that.

Regards,
Tom Barr

[Robert H]

Although I have never seen a need for cables either, there are people that swear by them, go to George Booths WEB site if you want to read the other side of the story. You have already spent the money for the product, there is no need at this point to have second thoughts. There are many ways to cook an egg so to speak.

Eco complete is the hottest thing going right now, and has gotten great feed back in all the forums from users. Whether you buy into the need or effectiveness of the nitrifying bacteria or not, the fact is it provides all the needed trace minerals, not just iron as Flourite does, and the live bacteria and organic material put the minerals into solution immediately, which a plain clay gravel does not. The live bacteria will also produce oxygen and C02 in small amounts in the substrate

Clay or laterite provides oxidized iron, which plants can not use until acids convert it to water soluble iron, (Fe2) So while you can certainly grow plants very well with other types of substrates, Eco complete certainly has it's benefits.

[Jeremy S]

Robert, after the Eco complete goes through shipping and storage in warehouses I’m not sure how much “live” bacteria you’re going to have in it. ;) The trace minerals that is has in it do look convincing and the fact that you don’t have to rinse it is great.