Jake’s Planted Aquarium Pages

We are carbon-based life forms and there’s really no getting around that. Plants are carbon based life forms too, so they need some form of carbon with which to continue the process of life and growth. The preferred method of giving aquatic plants the carbon they need is through carbon dioxide ( CO2). There is a certain level of CO2 which is going to be present in the water of your tank, through its continuing equilibrium with the atmosphere, but some of us have way too high of lights with difficult plants and need much more CO2 than what is present naturally. The lighting we provide is the throttle, so to speak. If you increase the light, you are putting your foot down on the gas pedal for the plants. Just like a car, the plants will run out of “gas” if you don’t provide it. If you slam the gas pedal down but don’t add the “gas”, your car might start to sputter and the same is true for the planted aquarium. In the case of a planted aquarium, an explosion of nuisance algae will likely be the result, which isn’t much better than a long walk to the nearest gas station.

Pressurized CO2 -  This is the “set it and forget it” method preferred by many. It involves more of a cost to set up than other methods, but after it’s set up you may only have to get CO2 refills, which are cheap, every 6 months to 2 years depending on CO2 tank size and such. In this method, a tank of beverage grade or medical grade ( usually beverage grade) CO2 is utilized as the source of CO2. This is the same Co2 that makes your fountain soda bubble.  A Co2 regulator is screwed on to the tank with a wrench. Co2 -resistant tubing goes from the regulator to an apparatus which dissolves the CO2 into the tank water. This apparatus can either be powered or un-powered, inside the tank or outside of the tank. Some CO2 regulators have an electronic solenoid on them which can turn the valve on or off through the application of electricity. This makes machines such as pH controllers able to regulate the amount of Co2 being introduced into the aquarium an automatic event, since the addition of Co2 lowers your pH level. A needle valve is usually a constant fixture on a Co2 regulator, providing fine-tuning of the flow of Co2. Many people use what is called a bubble counter which allows for you to see the amount of Co2 being sent to the aquarium as it bubbles through a liquid. Otherwise it’d be hard to see a colorless gas, eh?

Necessary for this set up is the Co2 tank, the Co2 regulator ( with needle valve), Co2-resistant tubing, and a method/device to dissolve the Co2 into the tank water. The solenoid, bubble counter, and pH controller are arguably optional, depending on who you ask.

For the basic set up you might expect to pay at least $200 USD. You also will need to find a local source of getting your Co2 refilled. Some welding supply places deal in beverage grade CO2 as well, so this warrants checking out. Otherwise there may be places that will fill fire extinguishers that can also fill your tank. You can even ask your local restaurant where they get their CO2 refills at, providing they have fountain soda.

DIY CO2- This set up involves a container, usually a large juice jug or 2 liter soda bottle, in which is mixed yeast, water, and sugar. As the yeast consumes the sugar, the by product is CO2. From there it is tubed into whatever contraption the person has with which to dissolve the Co2 into the tank water.  A check valve is usually placed in the air line between the bottle and diffuser/dissolving contraption to prevent tank water from siphoning into the bottle. You have to set up a new mix for this at least every month to insure consistent CO2 production. As the alcohol content in the bottle rises it kills the yeast and other bacteria responsible for eating up the sugar and making the Co2, so you can’t just add more sugar and shake it up and keep it going like that. There are many variations on how to set up some DIY CO2, some involving the addition of baking soda to act as a buffer to help prolong the active Co2 production, the addition of other nutrients or foods to help feed the yeast and maximize production, and I’ve even seen some that call for jell-o to be used instead of plain water. This site does a pretty good job in explaining your basic set up information for a DIY CO2 system. To it I would have to add that A) DIY CO2 isn’t feasible on larger tanks. On tanks larger than 30 gallons it becomes increasingly difficult to maintain a level of CO2 that is most beneficial for the plants. B) You don’t really need to buy bulkheads to fit the top of the soda or juice bottles. You can just drill a small hole and force the tubing through. The tubing itself will provide the seal. C) There are a lot of systems on the market now that have a container in which you add water and their “packets” of stuff for production of CO2. Most of them are just DIY CO2 setups that have been dressed up to look better, but it’s the same thing. If you buy one of these, like a Hagen Nutri-grow system, you can refill the canister with sugar, water, yeast, and a touch of baking soda instead of buying the “refill packets”.

Typically a person can not maintain as high a level of dissolved CO2 in their tank with a DIY system as they can with a pressurized system.

Carbon Block Co2 systems -  These systems operate on the premise that you have a block of carbon in the aquarium in a stainless steel holder that eats up your KH in the tank and produces CO2 as a by-product. It’s sound, scientifically speaking, but in practice it doesn’t appear to be as easy or work as well as a person would hope. The carbon block replacements are expensive and need to be replaced often. I do not recommend these to anyone. This is just one discussion on one forum regarding these types of units, and if you search on the internet you’ll find many more discussions that are similar.

“Liquid Co2 in a bottle” - Some of these claims are misleading , as what they have in the bottle might be a carbon source, but it’s definitely not CO2. The only liquid carbon supplement I know of, and use, is Seachem’s Flourish Excel. It is a bioavailable organic carbon source that plants can use, even if you’re already injecting CO2 into the tank via pressurized CO2 or DIY CO2. If CO2 is a 10 , then the Flourish Excel is a 6 or 7. Seachem does not tout this product as being “CO2″ or as good as CO2 as some of these other companies are doing.

“Just add this tablet for CO2″ - I’ve actually seen “CO2 systems” which basically comprised of a tablet that fizzed off CO2, like an Alka-Seltzer. You are supposed to either drop them right in the tank or into a little container that seals and has a air line that goes into the tank to some apparatus meant to dissolve the CO2. I find this sort of setup to be ridiculous at best and dangerous at worst. If you have a small tank and drop in tablets that produce CO2 uncontrolled, you can literally kill every fish in the tank. There is no regulation of this type of CO2. Also, there is no way to make it a consistent source of CO2. What you’ll get is a quick blast of CO2 which isn’t what is helpful to plants. Plants require a constant and consistent supply of carbon to meet their demands, not a sudden “burst” and then nothing. In my opinion, things like these are a monumental waste of time and money and companies that make things like this should be embarrassed to  sell them.