• You are viewing the forum as a Guest, please login (you can use your Facebook, Twitter, Google or Microsoft account to login) or register using this link: Log in or Sign Up

Introduction to CO2

19 Nov 2011
Introduction to CO2

CO2 is used in a planted tank as part of the carbon cycle known as photosynthesis, plants, algae, and cyanobacteria absorb carbon dioxide, light, and water to produce carbohydrate energy for themselves and oxygen as a waste product.

The Correct concentrations of CO2 in a fish tank is around 30ppm to much gas can cause aquatic life to become asphyxiated so drop checker is vital to keep and eye on the levels of co2 in the water

There are many methods of introducing co2 to a planted tank there's a liquid this is a chemical based method
a Home Brew method a disposable gas bottle method and a refillable bottle gas system.

Liquid Method
This is the easiest contain chemical called Glutaraldehyde but can work out expensive on a large tank there lots of products available now the will do this some better then others you just add few ml of a liquid product daily very easy.

Home Brew
This is were most of us start with a 3ltr bottle and 1/2 cup of sugar and a teaspoon of yeast these home made kits are OK for a start but not good for many reason like uncontrolled CO2 rates. which don't help with controlling BBA.

Disposable kits
These will have everything to get you going from the bottle of gas to all the pipes and diffuser these are used on smaller systems to about 100ltrs and far better then the Home Brew method yes there the cost of getting new bottles when you need a refill but the very easy to setup and use right out the box.

Refillable Compressed System
Has got to be the best method by far yes they can be expensive to setup and hard to find refills but this is the preferred method by most aquascapers giving you more control of levels with fine adjustment of a needle valve and the control of the gas at night time via a solenoid you can use a Fire Extinguisher or CO2 Bottle.

Basic equipment required for a refillable compressed CO2 system.

  • F.E or CO2 Bottle
    Regulator with needle valve
    CO2 Solenoid (so you can have it on a 24hr timer)
    24hr 7day Programmable Timer
    Bubble Counter
    One Way Valve
CO2 Drop Checker
These are vital in any planted tank injecting CO2 and allow you to monitor the CO2 levels these can be made of glass or plastic a tube/pot that hold a chemical called Bromo Blue mixed with a few mls of 4DKH water then placed 4" below the water level this will change color with the concentration of gas in the tank.

  • Blue = Low Level
    Green = Safe Level
    Yellow = To Much

4DKH Water
This water is used in your drop checker because it gives a more accurate reading then tank water you can get this from most good retailers its also available as just pure 4DKH water or premixed with Bromo Blue already to use in your drop checker.

Methods Of Diffusing CO2
Most people use a different method of dissolving the gas into the water the easiest is using a basic co2 diffusers these and made of glass or plastic and have a fine porous ceramic plate the diffuses the gas in to lots of tiny bubbles which you can see get small as they rise throw the water.

You can also use a reactor these connect to an extenal filter and as the water is passed throw the reactor the gas is introduced giving it a high exposure to the water and is meant to be 100% absorption rate that water is then pumped back to the tank by the filter flow although there is a downside to these restricting the flow on the filter a bit.

There are many types of diffuser and rector some better then others.
I am thinking of going the pressurised CO2 route but wanted some advice on whether to get a disposable cylinder or a refillable one. I have looked at both the JBL ProFlora u401 and the D-D Complete CO2 Set and just wanted to canvass your opinion on the merits of both. Also could I still use Easycarbo and fertilisers from http://www.aquariumplantfood.co.uk with a pressurised CO2 system or would there be no need for them.
I have also considered using a FE system but was wondering how easy and what cost they would be to refill

How long would a 500g cylinder last for and is CO2 injection only necessary while the main tank lights are on ?
My only other concern is how safe a pressurised CO2 system is ?

Sorry for the long list of questions :?

Hi Trev

All depend on size of you tank most disposable bottle system have limits to tank size there suitable for small setups and convenient and easy if LFS stock refills

A refillable bottle is better to see if you can find a re-filler first before getting it all to find you got to send it away to have it filled little bit of googling you should find someone local if not there the F.E route nearly everyone has a local fire extinguisher agent they will service and refill them

I use a refillable compressed bottle method as it last a lot longer then disposable systems

If your planning to use a 500g bottle you would probably be better to look at disposable bottle system but i would suggest if you can squeeze it in the budget would be to get a 2kg refillable bottle on a small tank this could last over a year

Estimate that a 500g bottle would last about 2/3 months on a 100ltr tank (depending on how soft the water is)

And Good Question
I forgot to talk about is yes you can use a liquid carbon and inject co2 as well this makes the injected gas more available to the plants and is method i use

Hope I've answered all ya questions
Thanks for the quick reply. I have as you a Juwel Vision 180 tank using just the normal filter but with a Juwel 1000lph pump although I have been informed that I should purchase a extra powerhead for distributing the CO2 more effectively.
The only reason I mentioned a disposable cylinder is because the all in one JBL disposable systems are cheaper than the refillables.
My tank consists of around 25 fish and I have java ferns and amazon swords together with a variety of mosses and the reason I chose hardier plants was because I have a few barbs (and did have a Plec which ravaged my plants)
Can you get refillable 2kg cylinders or is this size only available in a FE ? and do you use a FE ?

Hi Trev

Cool i like Juwel tanks, i use a 6kg pub bottle at 3/4bps it last me about 6 months i never used an F.E but should be same as a pub bottle you just got squeezy leavers on an F.E

I get my gas from a pub suppliers i just ring them when i need a bottle exchange you would be better to get the refillable bottle 2kg F.E should last you a few months but they do do bigger bottles

I no longer need to own a bottle i just ring the gas supplier up and he brings me a new bottle so would be easier if you can find a pub supplier they will sort you a bottle some may need a deposit on the bottles and when you need an exchange you just got to call them

I pay about £10 for 6Kg bottle every 6 months