Article written and graciously contributed by Karen Randall (@Krandall). You can purchase Karen's book, Sunken Gardens: A Step-by-Step Guide to Planting Freshwater Aquariums.
They say the pendulum always swings. Or what goes around comes around? I was a little amused when someone asked for an article on setting up a planted tank without supplemental CO2. Wait. What? People don’t know that you don’t HAVE to use supplemental CO2 to have a pretty planted tank?
NO folks, you do NOT need to invest in supplemental CO2 to have a pretty planted tank. If you Dose supplemental CO2, you will have a lot more choices in terms of what you can grow. Even if you choose to use low to moderate light levels and slower growth plants, the addition of supplemental CO2 will make your tank more stable and easier to care for. However, it’s entirely possible to keep a lovely planted tank and NOT use supplemental CO2.
Why would you want to do this? There are several reasons. The first reason people jump to is cost. “Adding a CO2 system to an aquarium is too expensive!” I cry foul on that one. Except for the smallest tanks, when you are setting up a planted tank, the marginal cost of adding a pressurized CO2 system to the set-up is just not adding THAT much cost to the entire set-up. And for little tanks, there are DIY citric acid/baking soda kits that will cost you $25 or less and will do the job quite nicely.
The second reason is fear. “I don’t understand CO2 and I don’t have the faintest idea where to start!!)” OK, this is real. Beginners are often afraid of CO2. They don’t understand how it works, they are afraid of hurting their fish; they might even be afraid of hurting themselves. They are also confused how to even get started. We can help with all that, but I think that’s a different article. Maybe more than one! This should STILL not be a bar to a beautiful planted tank, however.
Now we get into some that make more sense.
“I keep my tank in a classroom, (or in my child’s bedroom) where it is just not safe to keep a pressurized tank of gas.” OK, this is a real consideration. While there ARE ways of securing CO2 cylinders safely, I can understand why these might not be easy or acceptable either in a classroom or a child’s bedroom. So we’ll put this in the “good reason” column.
“I’m lazy and I don’t WANT plants to grow so fast!!!” Here is the crux of the matter for me. I have a lot of LITTLE tanks. NANO tanks. I TRULY don’t want to be trimming them all the time. If I have to trim them once every couple of months, I’m good with that! I want the tank to sit on my desk and look pretty with weekly top-ups, bi-weekly (sometimes monthly, if I’m lazy) water changes, and just cook along with minimal algae and still look pretty! Is that possible? Why, yes it is! And you don’t need CO2 to do it. I like to save my time and effort (and therefore higher light and CO2) for my larger tanks.
You DO need to plan carefully, and, alas, to some extent, you do have to have some luck in terms of your tap water, or else stick to small tanks and bottled water. That can work too, if you live in one of those places with liquid rock or other nastiness coming out of the tap. Softer water makes it easier to grow plants without the use of supplemental CO2. With a KH and GH of 5 or less you will have a pretty broad range of plants that you can work with. A really low KH will give you the best results of all. Especially if you use either a commercial soil based substrate. (Tropica, Landen, Fluval Stratum, etc.) or a mineralized topsoil substrate. Or, if you choose plants that do not need to take nutrients from the substrate, you can go with a non-nutritive substrate, like Safe-T-Sorb from Tractor Supply ($7 for 40 lbs) and supply all your fertilizer through the water column.
One of the most troublesome problems for beginners these days trying to start up a planted tank without supplemental CO2 with a standard “kit” tank from a pet store is exactly the opposite problem they used to have in the “old days”… It is still light. But when I first started talking and writing about planted tanks, I was always having to advise people to add light to their tanks. Now, with the advent of LED’s, most manufacturers are producing kit tanks with too MUCH light. The result is algae, and the response from beginners is to cut back on the number of hours that they leave the lights on. The problem is, this is not the real answer! The real answer is to reduce intensity, not duration. Duration should never be cut below 8 hours per day, or you can force many plants into “winter growth”, which is not attractive!
Sometimes it is possible to put a rheostat on the light cord, depending on how it is made. Nicrew sells one for their lights for about $10 on Amazon, and I’ve found that this has been compatible with several other lights, as long as they are the type that plugs into a power brick. If it is possible to raise the light higher above the tank, that is another way of reducing the intensity. Finally, you can reduce the intensity by putting something between the light and the water surface. This could be several layers of window screen. Or the material I like best is black plastic needlepoint canvas, which you can purchase at craft stores or Amazon (of course). This is tough, but easy to cut, and water proof, so you can make it fit just about any shape tank.
This is not to say that you can’t be successful with more light on a tank even if you are not using supplemental CO2, but it is a lot trickier. So for now, let’s stick with the easier way, which is with less light, and using slower growing plants. That also means less trimming will be needed!
Remember that you will still need to feed your plants, though not too much. For these slow growth/low light tanks, I prefer an all-in-one product like Niloc Thrive or 24 Aquarist All in One. Start with weekly water changes and only spread them out if everything is stable, your plants look good, and you have no signs of problem algae.
Some plants that will absolutely do well in this kind of slow growth, low light, no supplemental CO2 tank are Anubias, Java fern, Cryptocoryne, Marsilea hirsuta, Sagittaria subulata, and Bucephalandra (TC only, please!!!) There are certainly others that you can branch out into from there, but if you start with no more than this group, you will be successful, and can have a very pretty tank.
NO folks, you do NOT need to invest in supplemental CO2 to have a pretty planted tank. If you Dose supplemental CO2, you will have a lot more choices in terms of what you can grow. Even if you choose to use low to moderate light levels and slower growth plants, the addition of supplemental CO2 will make your tank more stable and easier to care for. However, it’s entirely possible to keep a lovely planted tank and NOT use supplemental CO2.
Why would you want to do this? There are several reasons. The first reason people jump to is cost. “Adding a CO2 system to an aquarium is too expensive!” I cry foul on that one. Except for the smallest tanks, when you are setting up a planted tank, the marginal cost of adding a pressurized CO2 system to the set-up is just not adding THAT much cost to the entire set-up. And for little tanks, there are DIY citric acid/baking soda kits that will cost you $25 or less and will do the job quite nicely.
The second reason is fear. “I don’t understand CO2 and I don’t have the faintest idea where to start!!)” OK, this is real. Beginners are often afraid of CO2. They don’t understand how it works, they are afraid of hurting their fish; they might even be afraid of hurting themselves. They are also confused how to even get started. We can help with all that, but I think that’s a different article. Maybe more than one! This should STILL not be a bar to a beautiful planted tank, however.
Now we get into some that make more sense.
“I keep my tank in a classroom, (or in my child’s bedroom) where it is just not safe to keep a pressurized tank of gas.” OK, this is a real consideration. While there ARE ways of securing CO2 cylinders safely, I can understand why these might not be easy or acceptable either in a classroom or a child’s bedroom. So we’ll put this in the “good reason” column.
“I’m lazy and I don’t WANT plants to grow so fast!!!” Here is the crux of the matter for me. I have a lot of LITTLE tanks. NANO tanks. I TRULY don’t want to be trimming them all the time. If I have to trim them once every couple of months, I’m good with that! I want the tank to sit on my desk and look pretty with weekly top-ups, bi-weekly (sometimes monthly, if I’m lazy) water changes, and just cook along with minimal algae and still look pretty! Is that possible? Why, yes it is! And you don’t need CO2 to do it. I like to save my time and effort (and therefore higher light and CO2) for my larger tanks.
You DO need to plan carefully, and, alas, to some extent, you do have to have some luck in terms of your tap water, or else stick to small tanks and bottled water. That can work too, if you live in one of those places with liquid rock or other nastiness coming out of the tap. Softer water makes it easier to grow plants without the use of supplemental CO2. With a KH and GH of 5 or less you will have a pretty broad range of plants that you can work with. A really low KH will give you the best results of all. Especially if you use either a commercial soil based substrate. (Tropica, Landen, Fluval Stratum, etc.) or a mineralized topsoil substrate. Or, if you choose plants that do not need to take nutrients from the substrate, you can go with a non-nutritive substrate, like Safe-T-Sorb from Tractor Supply ($7 for 40 lbs) and supply all your fertilizer through the water column.
One of the most troublesome problems for beginners these days trying to start up a planted tank without supplemental CO2 with a standard “kit” tank from a pet store is exactly the opposite problem they used to have in the “old days”… It is still light. But when I first started talking and writing about planted tanks, I was always having to advise people to add light to their tanks. Now, with the advent of LED’s, most manufacturers are producing kit tanks with too MUCH light. The result is algae, and the response from beginners is to cut back on the number of hours that they leave the lights on. The problem is, this is not the real answer! The real answer is to reduce intensity, not duration. Duration should never be cut below 8 hours per day, or you can force many plants into “winter growth”, which is not attractive!
Sometimes it is possible to put a rheostat on the light cord, depending on how it is made. Nicrew sells one for their lights for about $10 on Amazon, and I’ve found that this has been compatible with several other lights, as long as they are the type that plugs into a power brick. If it is possible to raise the light higher above the tank, that is another way of reducing the intensity. Finally, you can reduce the intensity by putting something between the light and the water surface. This could be several layers of window screen. Or the material I like best is black plastic needlepoint canvas, which you can purchase at craft stores or Amazon (of course). This is tough, but easy to cut, and water proof, so you can make it fit just about any shape tank.
This is not to say that you can’t be successful with more light on a tank even if you are not using supplemental CO2, but it is a lot trickier. So for now, let’s stick with the easier way, which is with less light, and using slower growing plants. That also means less trimming will be needed!
Remember that you will still need to feed your plants, though not too much. For these slow growth/low light tanks, I prefer an all-in-one product like Niloc Thrive or 24 Aquarist All in One. Start with weekly water changes and only spread them out if everything is stable, your plants look good, and you have no signs of problem algae.
Some plants that will absolutely do well in this kind of slow growth, low light, no supplemental CO2 tank are Anubias, Java fern, Cryptocoryne, Marsilea hirsuta, Sagittaria subulata, and Bucephalandra (TC only, please!!!) There are certainly others that you can branch out into from there, but if you start with no more than this group, you will be successful, and can have a very pretty tank.
