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Availability:
Only 5 left in stock, order soon!
Arrives
Sep 24 – Sep 25
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Size: 5.5L
Features
- Professional DIY Kit: a complete system in 5.5L size bottle, that includes SUS304 stainless bottle, regulator, precision needle valve, and easy adjustable bubble counter
- Safe: the bottle body is made of 1.5mm thick SUS304 stainless steel (25% thicker than normal 1.2mm bottle); it can sustain pressure up to 80kg/cm2(or 1137 PSI); safety valve will open automatically when the inside pressure exceeds the safety threshold
- Needle Valve with Bubble Counter: high precision, aquarium specific needle valve provides accurate fine-tuning; steady 1 bps is achievable; bubble counter with check valve built-in; it stops water from back flowing into your CO2 tank (protects your CO2 tanks from rust and corrosion)
- 12V DC Instead of AC Power: having the solenoid on a timer( not included), you can specify when you want CO2 injection on and for how long
- Attentions: the required powders to generate CO2 gas are not included; you will need purchase the citric acid and sodium bicarbonate powders separately. Fzone will offer a round-the-clock service, and you can reach out to us at any time for any product-related concerns.
Description
— Enjoy the Art of Aquascaping Founded in 2018, Fzone creates aquarium products that combine high quality with clean, aesthetic design. What began as a passion grew into a mission — to offer products that are reliable, precise, and visually refined. We focus on CO₂ systems and aquarium accessories that improve plant growth while keeping setups neat and elegant. Thank you for your support — we look forward to growing with you. INSTRUCTIONS Q: Is the bottle body strong enough under the pressure? what are the specific parameters? A: Yes. The bottle is completely safe. The bottle has a safety valve built-in. It will open automatically when the inside pressure exceeds the threshold CO2 generator is based on the principle reaction of citric acid and sodium bicarbonate mix with water, high purity of carbon dioxide gas is produced. After fully reaction, the CO2 goes through a pressure regulator, bubble counter and diffuser, provide a stable output pressure and flowrate, supply CO2 for photosynthesis, completely solve the disadvantages of the reactive generator pressure instability. Fzone‘s CO2 generator kits included almost all stuffes needed in auqatic co2 system. ● OTS 12V DC mini solenoid valve, safer than AC solenoid. ● Energy-saving - low power consumption: 0.4 watt only. keeps the solenoid cool to the touch during operation. ● Use with a timer, solenoid valve allows for CO2 to be switched on/off at defined times, e.g. to synchronize with the aquarium lighting. ● Red LED on/off indicator - the operation (on / off) of the solenoid valve can be confirmed by the red LED. ● No noise - without buzzing or humming sound. ● High-quality model - OST brand, special structure for long-lasting durability and dependability.
Brand: FZONE
Liquid Volume: 5.5 liters
Item Weight: 3.24 kg
Item Form: Liquid
Number of Packs: 1
Package Dimensions : 17.4 x 10.79 x 7.05 inches; 7.14 pounds
Item model number : FZ-4LKIT-US
Date First Available : February 23, 2023
Manufacturer : FZONE
Best Sellers Rank: #61,209 in Pet Supplies (See Top 100 in Pet Supplies) #206 in Aquarium Air Pump Accessories
#206 in Aquarium Air Pump Accessories:
Customer Reviews: 4.2 4.2 out of 5 stars (1,003)
Brand Name: FZONE
Number of Packs: 1
Unit Count: 1 Count
Manufacturer: FZONE
UPC: 764595876395
Number of Items: 1
Item Highlight: Easy-to-Refill, DIY CO₂ System, Stable CO₂ Output, Safe Reliable, Regulator, CO₂ Diffuser, CO₂ Tubing and 12V DC Solenoid
Model Number: FZ-4LKIT-US
Manufacturer Part Number: FZ-4LKIT-US
Liquid Volume: 5.5 liters
Item Weight: 3.24 kg
Item Form: Liquid
Pet Type: Fish
Target Species: Fish and Plants
Frequently asked questions
If you place your order now, the estimated arrival date for this product is:
Sep 24 – Sep 25
Yes, absolutely! You may return this product for a full refund within 30 days of receiving it.
To initiate a return, please visit our Returns Center.
View our full returns policy here.
To initiate a return, please visit our Returns Center.
View our full returns policy here.
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Similar Products
Top Amazon Reviews
Size: 2.5L
I'm a first time CO2 user and this is my second venture into the aquarium hobby. My first go round, I always wanted an nice lush planted tank but I was in my early teens and couldn't afford the size tank or the items required for that kind of setup. Now on my second go round, I decided to follow that path of my dream aquarium and with that came the initially overwhelming prospect of CO2 systems. The Fzone CO2 generator system has made that very simple and significantly less daunting for me. It comes with almost everything that you need to set up the system. The only things the system doesn't come with is sodium bicarbonate, citric acid, a digital scale, or check valves. I highly recommend you spend a couple dollars on check valves. Those check valves will keep water from backflowing into the co2 lines when you have the system off. If you want to make your life super simple, you will need them. They also allow you to easily disconnect the bubble checker when it comes time to refill the bottle with your baking soda and citric acid. Now, I did say I'm new to CO2 so I did make a mistake when filling the bottle. The directions specifically state to hold the bottle at a 45 degree angle when filling. I did this until I went to grab the cap. When I reached for the cap of the tank I set the canister straight up, which meant I ended up having a fountain of the chemical reaction shoot out of the top of the tank until I was able to screw the cap onto it. Don't make the same mistake I made. That was my own mistake I made, like I said I knew it had to be held at an angle and I had an airheaded moment. Now I will say, if you have a larger tank, go for the 5L kit. I have a 75 gallon and I have had the CO2 on a timer, and my tank pressure has gone from 400+ PSI when freshly full to 150 PSI in 4 days. I will most likely need to upgrade to the 5L bottle here in the next month or so, but I also have my system running for 11hrs a day. As stated, the tank pressure goes up to over 400PSI, which already tells me that the build quality is quite superb, and I noticed some other reviews state that the knob to adjust the bubble flow was a bit touchy. My specific system was just touchy enough to where it was actually pretty easy to set my flow rate at 3 bubbles a second without really struggling with having to fiddle around with it. The tank is pretty weighty, but I believe that's due to the fact that it is built very well. When you initially fill the tank it will get cold enough to condensate on the outside, but that is due to the chemical reaction. It's not a flaw. Overall the 2.5L was perfect for me to dip my toes into the beautiful world of planted tanks, and is good value for people who have a smaller setup, such as a 29G or less. For my specific use case, I will need the 5L so I don't have to refill every week.
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Reviewed in the United States on June 17, 2025 by H3AVYTR00P3R
Size: 2.5L
Fzone has fantastic customer support (thank you Cheryl). I was missing the white piece on my filter and they sent me a new filter. I have used an fzone regulator on a paintball tank previously, but I had a stroke, and it's no longer possible for me to go get CO2. Therefore, I looked for a CO2 generator and was happy to find that fzone had this one Because of my previous familiarity with using CO2, despite the horrible instructions, it was quite easy to get set up and get started. This unit came with a solenoid which works perfectly. I have it on a timer to turn on in the morning and shut off at night. I replaced the diffuser with one from clscea (stainless steel, widen hook 25cm) which works much better, especially for rimmed tanks. The supplied funnel's base is too narrow to be of real use (fzone please replace this). This unit no leaks, it's looks great, runs quietly, gives me great value for money, and I have to trim my stem plants more often now and my plants look fantastic Fzone makes great products and I will buy from them again.
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Reviewed in the United States on October 8, 2024 by Ali
Size: 2.5L
No seal problems, all parts there, instructions are mostly good. If you dont have a scale, you'll need to do a little math. I added 13.8 Tablespoons Baking Soda, and 8.3 Tablespoons Citric Acid with my 300ML water and it seems to be working out... but again do your own math and make sure do NOT take my word for it. It's been a few weeks and my plants seem happy and my fish are alive so those measurements haven't killed my 29G just yet... Anyways, the setup seems ideal and is decent price as far as I can tell. It does the job well, and hasn't failed me yet. Seems like it's decently made so I'm happy with my purchace. Would buy from this seller again. On a final note... buy a CO2 drop checker. I did some math and figured 1 bubble per 2 seconds was good.... now I'm using 4 bubbles per 1 second. It will help you figure out how much to be adding to your tank and save you mental stress trying to guess. Just take it SLOW and figure out what rate gets your checker green fastest and keeps it green without going into the yellow (danger) zone.
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Reviewed in the United States on April 24, 2024 by KaibaCorp
Size: 2.5L
It’s a pretty solid system. The needle valve is a little sensitive for my taste. It’s not bad but it could be a little better. The materials are all high quality. The system is running well without any issues. The diffuser is a little on the low end. The bubbles are a mixture of good micro bubbles and some larger bubbles. I would recommend getting another one if you want tiny bubbles all around. It’s solid though as none of the bubbles were large. The system was easy to set up. They say use 200 grams of citric acid and 200 of baking soda. Chemistry says you need 200 grams citric acid and 260 grams of baking soda to get a perfect consumption in the chemical reaction based on the mole weight of each. I went with science to avoid having a lot of left over matter when the tank needs to be refilled. You can avoid the crust or unused citric acid some complained about in the tank this way as all the citric acid will be used in the reaction. That’s a pretty minor issue though. All in all, it’s a good build and quality materials. I got some pearling of my plants day one. The price isn’t bad given everything. I would have given 5 stars for a slightly better needle valve and a slightly better diffuser but it’s a good quality system. Update: Day two my diffuser is even worse. The plate doesn’t seem attached and all the co2 is just leaking out the edge of the diffuser. Definitely a four star product because the diffuser is worthless. But that’s my only complaint. Solenoid runs cool, everything else works great.
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Reviewed in the United States on May 2, 2025 by SlimChiLion
Size: 2.5L
This whole kits garbage. Every part except for the canister itself broke. One by one, it was first the solenoid, replaced it with the replacememt solenoid F zone sells, that also broke, and then so did the second one. Mind you, this is all under 2 months. Then the control valve broke and leaked a ton, so I had to replaced that. Then the bubble counter cracked on the bottom thread, again a huge leak. This thing wasn’t built to handle an attack from a butterfly. So in all I’ve bought the kit, 3 replacement solenoids, a new control valve (the part that screw into the top of the canister), and now I’m about to buy a replacement bubble counter. Garbage! The only thing that stands up is the canister itself and I bet that’s the only part F-zone outsourced. From experience, if you guys want a good solenoid, buy the Clscea one in my photos. And I tried replacing the seals on the control valve to stop the leak, to no avail. It literally shot baking soda all over everything for a good 7 minutes straight with no way to stop it. And a citric acid/baking soda mix is so difficult to clean if you let it dry, cleaning solutions don’t dissolve it. So I guess ill just live with the baking soda spray all over my aquarium cabinet. I hate this kit!
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Reviewed in the United States on October 24, 2025 by CU
Size: 5.5L
I have been running this setup on my 29 gallon heavily planted tank for about 6 weeks now. Ive had such a great experience with it that I ordered a 2nd setup for a 75 gallon tank that I am in the process of building. Pros: - High quality parts - Efficient CO2 generation. I have have a half a tank worth of pressure after 6 weeks - Easy to read gauges - All of my plants are growing like weeds. I've already had to trim them twice - The glassware that's included is very nice. - Plenty of length provided for the co2 hose Cons. - The instructions need work. Maybe it was me, but I had a hard time understanding them. I found a very helpful video on YouTube that clarified the math behind the citric acid & baking soda ratios. - The needle valve is very sensitive so you have to be careful to let the bubbles even out after touching the adjuster to get an accurate count. Other notes: - The setup is very tall when built. All the pieces mount vertically as well as the connection for the c02 house. I planned on having it in my cabinet but I didn't account for the bubble counter and hose being on top so it wouldn't fit. - The glass "U" connector is sized for a rimless tank. I had to cut a small notch in my tank to be able to use it. It is an easy modification to do but it something you need to consider. - A smart plug that allows for daily schedules makes controlling the system a breeze. I have it programmed to turn on at 8 am and shut off at 5pm. Running co2 at night is a waste as plants don't utilize CO2 without light. My lights are also on a controlled schedule as well but that's a different topic. Over all, this setup is a great way to get started with CO2 injection without having to drive around a find someone to fill CO2 canisters. It's possible it's more expensive to run long-term, but for me, being able to order citric acid and baking soda on Amazon that will last me an entire year vs lugging a tank to a paint all store is 100% worth it. I hope Fzone decides to make a 1 liter or even a half liter generator that I can use on my nano desktop tank.
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Reviewed in the United States on November 26, 2025 by Dougie Fresh
Size: 2.5L
Overall happy with my purchase and the price of the kit. The instructions included could be a bit clearer and seemed to skip over the installation of some of the parts, which I think is especially important for someone like me who is brand new to CO2 in aquariums. That said, assembly was easy enough. Needs a separate timer switch to utilize the solenoid valve, which seems to do a much better job of sealing the whole thing off than the valve on the canister itself anyway. Only other thing I'd note is the diffuser that came with my kit was cracked/chipped and not working correctly (still diffusing but not very efficiently, and with a pretty unpleasant hissing sound), but the seller was quick to send me a replacement which is working perfectly. Can't yet speak to how the whole kit will last over time as I've only been using it about a week now, but so far I'm quite happy and would recommend it (and the seller) based on the overall experience, my limited knowledge, and having shopped around a bit before buying.
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Reviewed in the United States on May 8, 2024 by Bobby
Size: 2.5L
I’ve been testing this FZONE CO2 system for about 2–3 weeks now and I’m very happy with it. It has maintained enough CO2 to consistently keep my drop checker green, and I’ve already been able to start growing more demanding plants. I’ve introduced several red plants and have Monte Carlo beginning to grow in as well. The system has been straightforward to use and has maintained pressure reliably so far. For a small high-tech planted tank, it has been a great way to get into injected CO2 without needing a traditional pressurized cylinder setup. Very pleased with it!
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Reviewed in the United States on September 17, 2026 by Claire