A good CO2 system is an often overlooked, but critically important part of a successful planted tank (i.e one that supports good plant growth, that can allow one to grow carpets and more demanding species easily etc.)
I strongly recommend investing in a good regulator, in the same way that it is wise to invest in a reliable computer CPU: it is a sophisticated component that has a huge impact and hard to troubleshoot if problematic. In INDIA, Aqua Zones has a great reputation. CO2 Art is another reliable brand.
To diffuse CO2 into the tank, the easy and proven path is through an in-line atomizer: you want one that produces very fine mist rather than bubbles. If you do not want any CO2 mist (read here for details) go for a CO2 reactor but be aware that reactors come in far more varied designs- some work well, many don’t. A example of one that works well is listed below.
Below are brands / tools that I have used or have experienced to a degree that I’m fully comfortable to recommend. If you do buy the products through the Amazon links below, I do earn a small commission (at no extra cost to you), which helps in the running of this website.
CO2 Regulators
Good regulators are worth it as they last a long time and have good resale value. Tuning CO2 is critical to growing plants well – while failures have heavy consequences for livestock. Cheaper regulators have higher chances of leaks and may inject at irregular rates. FZONE and CO2 Art produce high quality dual stage regulators that you can find on their site.
For budget conscious folks, Aqua Zones has a entry level egulator in Mufan and ZRDR Brand that works well for the price.
CO2 diffusion devices
Inline atomizers (as opposed to in-tank atomizers) introduce a fine mist into the tank through the filter output line. They are the easier to tune compared to reactors. I use this style of Inline atomizer for most of my tanks.
CO2 reactors aim at 100% dissolution of CO2, but are harder to tune. Use these instead if you do not want mist in your tank.
Improving gaseous exchange
A surface skimmer helps to keep the water surface clean, and improves gaseous exchange; which is essential for optimizing CO2 levels. I would not run a planted tank without this very simple but invaluable device.
Other CO2 peripherals
CO2 resistant tubing. Lasts longer than normal air line tubing and corrosion resistant.
Bubble counters are useful for checking the flow of CO2.