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CO2 for Dummies - A Practical Perspective

CO2 for Dummies - A Practical Perspective

Tips by Dou Mok, Felix Smart Ambassador 

If you're starting a freshwater planted tank, you will inevitably run into the question - do I need CO2 to grow plants? The short answer is no - you actually don't need CO2 to grow plants. The long answer is not for dummies - so I'll leave that to the experts* to discuss. However... "no" doesn't mean that all plants can't benefit from CO2 injection. So, what do you really need to know?

* https://www.advancedplantedtank.com/blogs/choosing-co2-why

Buy things once, right - not twice.

There is no question that you should consider buying and setting up a CO2 system if you are serious about growing plants underwater. There are various options out there, but the one I recommend is the option that involves a CO2 Cylinder and a Regulator with Solenoid. Do your research and buy products from reputable brands so that you can focus your attention on your tank and plants. Injecting CO2 is something you will want to put on a schedule and automate, so that you don't have to manually turn on and off (Use the FelixSmart's Range feature!).

Take things slowly at your own pace.

It might be tempting to add a lot of CO2 in your tank at first, because you want your plants to grow fast, but adding CO2 does come with it's own complexities. With any new element that you add into your tank, you should take things slowly so that you can observe the changes. Start with 1 bubble per second and see what happens after a week. If you have many plants, consider starting with 2. Make sure that your CO2 bubbles are being spread all throughout your tank - this might mean moving your CO2 diffuser underneath your outflow! If your tank is one that develops an oily film on the surface, add a skimmer and set that on a timer (use the Felix Smart's Range feature!). If you have fish, they will appreciate you giving them some time to get used to the CO2.

"The Water Tests" vs. "The Eye Test"

How does one find out if one's tank has enough CO2? You can either test your water parameters (pH/kH) or do an eye test. The eye test is about confirming that your plants are growing by observing whether you see pearling (photosynthesis) or not. George Farmer* describes this best - it happens when plants have the food they need to grow so well that they start to form visible bubbles of oxygen on their leaves. You should be able to observe this happening within 2 hours of your lights turning on if you inject CO2.

If you really want to get into this more, I'll leave you with some verbiage from Tom Barr**: "Adding CO2 increases photosynthesis 10-20X normal rates without adding it, thus the O2 is produced at a much higher rate. This leads to more pearling due to O2 production by the plants. Oxygen is pretty insoluble in water to begin with, CO2 is not. Try and get 50 ppm of O2 into your tank's water sometime. Water is equilibrated with air at 100%(say 7 ppm at 28C), but it's so "saturated" that O2 forms into bubbles and pearls away."

The water test is not for dummies so if you're ready to challenge yourself, here is some advice from Dennis Wong***, author of "Advanced Planted Tank": "As a very general guide, if you have KH values between 1 - 10 dKH, aim for a 1 point relative pH dropfrom the point when CO2 injection is not yet turned on to the time after it has been turned on and CO2 has risen to a high, stable equilibrium point."

If you have a Felix Smart, you can easily monitor the pH through the App as a rough way to gauge your CO2 levels. Practical.

* https://www.youtube.com/channel/UC210QPUiYoCjm9IEuu5SHLQ
** https://barrreport.com/
*** https://www.advancedplantedtank.com/blogs/choosing-co2-why/the-wrong-way-to-read-the-ph-kh-chart

Remember, every tank is different just like we are as humans. The right answer is the one that works for you and your plants - don't feel pressured into doing something that you don't feel comfortable with (or at least do your research!).



3 Easy Steps for Crystal Clear Water

3 Easy Steps for Crystal Clear Water

There is nothing quite like having crystal clear water in your aquarium, but achieving crystal clear water is not always easy. Particulates like dust and debris, tannins from driftwood and suspended algae can make your water look foggy, discolored and dirty overall. The good news is, there are 3 simple steps you can take to help remove any unwanteds from your water and achieve that stunning clarity all aquarists strive for!

STEP 1 - Activated Carbon

Activated Carbon is a chemical media that when added to your filter, or aquarium directly in a media bag, will absorb a wide range of chemicals including tannins, and other substances that can cause discoloration to your water. If your water happens to be a little smelly, activated carbon is going to help remove that as well.


STEP 2 - Fine Filtration

Poly pads, filter floss and felt pad media with a small micron rating placed inside your filter are some of the best options for removing small particulates like dust, mulm and even suspended algae from the water column. Most filters will have branded options for fine filtration, but best results may come from a specialized cut-to-fit micron pad with a rating of 100 microns or less. Keep in mind that this filter media should be used for maintenance only and not all the time since it will bog up quickly with dirt and debris. 24 to 48 hours is usually all it takes to get the job done.


STEP 3 - Water Clarifier (Flocculant)

The last step that will really boost the results of step 2 is the addition of a water clarifier. In essence, a water clarifier is a liquid additive that acts as a flocculant to bind all of the tiny particles in the aquarium into larger clumps, making it much easier for your fine filtration to pull out even the tiniest of particulates. This is where we most often see the water really clear up to the point where it looks like our fish are floating on air!


Following these 3 steps has a proven track record of excellent results and can be the secret weapon of any aquarium owner looking to achieve that highly sought after ultra-clear water.

5 Easy Aquarium Plants for Beginners

5 Easy Aquarium Plants for Beginners
Adding live plants to your aquarium is a fantastic way to create a natural looking tank that functions like a complete ecosystem by removing excess nutrients from the water. Planted tanks can also have a complexity to them that makes them a challenge for newer aquarium owners, but not all plants are difficult to provide for and this list will give you 5 great options if you are looking for easy-to-grow aquarium plants!

Java Moss

One of the easiest and simplest aquatic plants to keep is Java Moss. It grows under a multitude of light intensities, with or without CO2, with or without fertilization and can be attached to driftwood, rocks, plastic grid, or just about any other surface to create a carpeting effect. Java Moss, when grown bushy, can serve as a hiding place for baby fish and shrimp. It is also a great tool for helping to keep nitrate and phosphate low. How quickly it grows will depend on the conditions you provide.


A unique plant that has rigid and robust foliage sprouting from a rhizome, Anubius is another plant that happily grows on driftwood, rocks, ornaments, or even rooted into plain pea gravel. Anubius is a notoriously slow growing plant but has the distinct advantage of being nearly bullet-proof in low light and low nutrient conditions, making it an excellent beginner plant. There are many varieties of Anubias ranging from the small ‘nana petite’ to the larger ‘barteri’ making it easy to find a good placement in your aquascape for an Anubias, whether it is low in the foreground, or tall in the background. Anubias is also a good option for aquariums with fish notorious for eating plants as the rigid leaves are much more difficult to damage.



If you are looking for a plant with interesting leaf texture, more earthy tones and coloration, Cryptocorynes are a great option. They have quite a range in leaf size, shape and come in a wide variety of colors from light greens, dark greens and browns to bold reds. They do well in systems with medium light, with or without CO2, and minimal fertilization. Cryptocorynes can work well as midground and background plants in smaller aquascapes and as foreground and midground plants in larger aquascapes. A few notable species are wendtii, crispatula and undulata.


Java Fern

Much like Java Moss, Java Fern is an easy and robust plant to keep that grows in just about any aquarium setting. Being a true fern, it has prehistoric looking fronds with sori (little orange-brown dots) along the underside of each leaf. Java Fern is also a rhizome plant and is easily attached to driftwood, rocks or planted in just about any substrate. It can grow quite tall and busy making it an excellent midground and background plant. There are several species readily available including narrow-leaf and trident-leaf varieties if you are looking for something more elongated and wispy.

Jungle Vals

Last but not least on the list is Jungle Valisneria, also called ‘Vals’ for short. Jungle Vals grow long and tall with leaves that are straight and flat like grass. They grow easily in almost any aquarium setup with a moderate amount of light. They also uptake nutrients quickly because of their rapid growth and can do a good job of reducing nitrates and phosphates in the aquarium. They make a fantastic background plant and will lie across the surface of the water if they grow too tall. Trimming is easily done to keep the leaves shorter if desired. Overall they are an excellent choice for a first time aquatic plant owner!

Give these plants a try and transform the look of your aquarium while adding the benefits of an ecosystem for your fish!

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