CO2 system reference material

[Cliff]

I would like to learn more about how CO2 systems work. Specifically I would like to learn about the hardware required and how it all works together to put CO2 into the tank. I’ve been able to find a lot of info on the pros and cons of a CO2 system, but nothing on the mechanics of the system.

Are there any good books or other reference materials I should be reading?

[Michael Milligan]

:search:

Let us know what you come up with :)

[Cliff]

Let me re-word my question.

I’ve been looking into different co2 systems that I’ve been able to find on various websites. There seams to be a lot of vastly different options on what is and is not required. For example, I found information that states a PH controller is critical to any system or really bad thing could happen, then other site states PH controllers are a large waste of money as manually controlling amount it the only option (yet they don’t explain how to do that).

I’m trying to understand what hardware is actual required and why.

I’m hoping that someone with experience can point me the right direction.

[Michael Milligan]

I have two tanks with soda bottle co2 units. A tube into an airstone leads back to the bottle 1/2 full of sugar and yeast.

I run the bottle like a sourdough starter. When it stops bubbling I dump out 1/2 the solution and add more fresh water and sugar.

Trial and error mostly.

[Cliff]

Micheal, are the DIY set-ups like you have discribed better than using the compressed gas set-ups ?

[Cliff]

Micheal, are the DIY set-ups like you have discribed better than using the compressed gas set-ups ?

Just to clearify, When I use the term compress gas set-up, I'm referring to set-ups like the below link:

[Only Registered Users Can See Links.]

[rich311k]

Pressurized is the way to go. It is consistent, and hands off once you get it locked in. I have two setups, the first I bought all the good equipment from Rex Griigg put the whiole thing together, works fine. Cost me somewhere around 250 dollars.

Second one I bought the semi automatic system from Dr. Foster and Smith. works better, cost half as much. The bubble counter it came with sucked so I bought a new one, but that was it.

[Cliff]

Thanks Rich :19:

I hope you don’t mind two more questions, (blush)

Do you use any other equipment with your CO2 systems like the PH controllers ? I’ve read a lot of controversial information about them and I’m just wondering how useful they really are. I wouldn’t think they are required, are they? To me it just sounds like it’s only a matter of starting off really slow (putting in the least amount of co2 in to start) and working your way up by adding a little more each time getting to a balanced amount your plants will consume without upsetting anything else in the tank. As every tank is different, I think that would be the best control method to get a balanced tank.

And do you run your co2 systems on a timer to come on with your tanks lights?

[rich311k]

I do not use a PH controller, the CO2 comes on and off with the lights. I use a drop tester and observation of the plants and fish to decide when I have enough CO2.

You do want to go slow and start the system up when you will be home for a few days so you can observe and be sure the fish are safe.

[chrisfraser05]

Right. I've been looking into this for ages and have found out pretty much what you are looking for.


Pressurised CO2 systems are broken down into Four parts.

Storage

Regulation

Absorbtion

Monitoring



Storage

Firstly on the storage side of things you are looking at the Cylinder.

Your options here are endless. At the bottom end (maybe not for price) is the small 600g-1kg bottles that normally come with premade/shop bought Aquarium systems.

Next up from here you would be looking at Fire extinguishers and welding bottles (2-5kg).

After this you are looking at industrial/commercial bottles anywhere from 6-40-50kg. These would normally be hired at an anual cost and when running low you phone and they deliver a fresh one for a single fee. These are the ones restaurants and bars use.

Regulation

For the Regulation you need some way of controlling the output from the bottle.

At the most basic level you need a controllable valve (a needle valve) which you can turn up and down to control what is comming out.
The idea setup for this would be a manifold with two guages and a valve between them.

The first guage will show you what pressure the bottle has and the second guage will show you what the output pressure after the valve is (allowing you to choose the pressure).

To this you could choose to add an electical controlled solenoid. With a solenoid you can have a timer plug on it meaning you can have the CO2 coming on and off just before your lighting and also you know in a power cut the CO2 would stop flowing... This could save the lives of your fish if the filter was also knocked out with the power.

Absorbtion

This is how your CO2 enters and mixes with your water.

The least effective but never the less widely used methods are using an airstone and the other is to have a large area of CO2 open to water to dissipate. To do this you could have an upturned saucer at the bottow with the end of the CO2 hose under it. The water passing by this bubble with absorb some of the CO2.

The next method some use is run the CO2 hose directly into the inlet of an external filter. This deffinately would allow the CO2 to dissipate effectively but there is much debate wether or not the bubbles hitting the fins of the impellor can cause damage. In my personal opinion its a risk not worth taking.

Lastly the two best methods are to use either in inline or in tank diffuser.
The in tank diffusor pushes the CO2 through a ceramic disk with microscopic holes making the CO2 split into tiny bubbles which are absorbed into the water.
The inline is very similar except it is outside the tank in the filter outlet hose meaning the CO2 is in the water as it arrives into the tank.

Monitoring

To monitor the CO2 levels again there are a few ways. The least favoured (but again, god knows why, some people use it) is to keep turning it up until you see an effect on the fish. Once you see them gasping for oxygen turn it down till they recover!!!!

A bubble counter can be used to see how many bubbles of CO2 are going into your tank over a period of time. This is a good way to tell if your CO2 is still the same rate however really tells you nothing about if this is the right amount for your tank.

The best way is to buy whats called a drop checker.
You fill a drop checker with 4 dKH solution which is just a controlled sample of water at 7Ph and 4 dKH. To this you add a reagent (basically the PH test kit solution) or you can but 4 dKH with reagent already in it.

You put the solution into the checker and put the checker in the tank. There is an air bubble between your tank water and the solution. The air will absorb CO2 out of your water and the agent will then absorb some of this (basically they all equalise in CO2 saturation) and the agent changes colour depending on how many ppm of CO2 there is.

A blue colour indicates low CO2, a lime green clour indicates around 30ppm (ideal for fish and plants) and yellow would indicate above 30 ppm which is too much for the fish to be comfortable and longterm will kill them.





Here is the bits I've just bought to build mine;


Fire extinguisher

[Only Registered Users Can See Links.]

Reg

[Only Registered Users Can See Links.]

Sol

[Only Registered Users Can See Links.]

Tubing

[Only Registered Users Can See Links.]

Diffuser/counter

[Only Registered Users Can See Links.]

Check valve

[Only Registered Users Can See Links.]


Reagent

[Only Registered Users Can See Links.]

drop checker

[Only Registered Users Can See Links.]





With regards to PH controllers, I don't believe they are worth the money and have heard of some people who have issues with them.

The way you use a drop checker is to turn the amount of CO2 up a little each day and monitor the colour as the days progress (unless you start without fish then you can whack it up high then come down slowly).
The CO2 level in the tank will change slowly throught the day and peak at some point, this is when you want the checker to be a nice lime colour.
The checker however does work slowly so when you look at it you may be looking at the amount of CO2 a few hours ago not what its currently at.

This is the problem with PH controllers. The PH controller replaces the valve for controlling the pressure and also reads the PH of the tank. Again what it may be reading can be based on what the CO2 was like hours ago.
It then will put the CO2 up and down to try and maintain the PH level.
This can cause CO2 levels to be very up and down which isn't very good for plants.

One last point to observe is that as the pressure in the bottle slowly goes down the amount coming out of the regulator will drop inline with this so as the time goes on you need to turn is up a little now and then to maintain the CO2 amounts. The larger the bottle the less you need to do it.
This is where a bubble counter pays. You use the drop checkers to initially setup your level but if you also have a bubble counter you can take note of how much your tank needs. If say your tank is running at 5 bubbles per second you can just quickly check this once a week to know if you need to adjust the valve.

We can go into the importance of circulation at a later point though lol

Chris

[chrisfraser05]

Also some stuff on here!

[Only Registered Users Can See Links.]

[Michael Milligan]

Micheal, are the DIY set-ups like you have discribed better than using the compressed gas set-ups ?

Better for me. They cost nothing and provide most of the benefit.

I imagine with more sensitive livestock controlling the ph would be more critical. If my fish behavior/health were effected then I might reconsider :)

CO2 is just one factor. CO2 won't help a plant in poor light.

[Cliff]

Thanks for the great info guys.

I really appreciate the info.

Thanks again

[Cliff]

Thanks Mike.

I've got pretty good lighting. That was the first step for me. Now I'm just tring to learn as much about CO2 systems as I can so I can figure out what is going to be the best fit for the tank as well as the wife and I.

[CGY_Betta_Guy]

I have found this primer ([Only Registered Users Can See Links.])to be a very good source of parts knowledge and info when I was looking. Explained each component pretty clearly and made it easy for me to find used systems since I knew what I wanted to be part of the system.

I dont use a PH controller but use the CO2 drop checker as it seems to be a pretty good indicator for me.

So quick summary, the important parts are the tank, regulator, washer, solenoid, needle valve, tubing and good lighting. Optional are bubble counters (but make it easy to see how much CO2 is being injected), ph controller, check valve (I use these for when the solenoid shuts off for the night..just in case.), specialized tubing, and your chosen method of diffusing the gas into the tank (reactor, bubble ladder, diffuser, bell). I use diffusers.

Hope that helps.

Edit: actually I think a solenoid is also optional if you are not planning on turning off CO2 nightly and have a very good needle valve to control consistent CO2 input.

[Michael Milligan]

Perhaps I also find the simple elegance of a yeast starter in a bottle more appealing.

Cliff, unless your wife is also an aquarium person, I'm sure she will see a yeast bottle as a sound first step. Preliminary research. You very well my find the need to step it up, or you may not. Besides, if enough of the plants in your tank respond well to this treatment you will run out of space FAST! lol

Spend the $200 on a bigger tank off Craigslist hehehe! :)