Aquarium DIY CO2 Kit: Citric Acid/Vinegar and Baking Soda

I had a spare 5 gallon tank and I had been toying with the idea of doing up a planted tank with fish, and going semi high-tech with a DIY CO₂ kit. And some people might ask “Is DIY CO₂ really worth the trouble?”, or frequently you will see on forums and FB groups that DIY CO2 is a waste of time.

Content

Why Choose DIY CO2?
Citric Acid or Vinegar?
How to Set up
How to Start the Reaction
Citric Acid Gone Over Night?
Use a Reactor

Why I chose DIY instead of a pressurised CO₂:

Pro

1. Low initial cost
2. Ingredients can be purchased locally, and stocked up.
3. Ingredients are everyday item and can be used for other purposes. (Your wife will never complain if you stock them up!)
4. Whenever I run out of ingredients, I can get the system up and running away shortly.
5. Refilling CO₂ tank at the nearest LFS is 16km away. Imagine the time and fuel cost.
6. Refill sometimes are not 1-for-1 exchange and need to wait for a few days. Again I will need to travel 16km to collect it.
7. The LFS will be closed by the time I knock off from work and travel down for 1-for-1 exchanges. That leaves only weekends. And we all know weekends at the LFS is a nightmare. Furthermore, I have 2 kids and weekends is all about family and not so about plants in a tank.

Con

1. Low capacity compared to Pressurised System’s 2 month running time. (unless it’s the high pressure DIY CO2 canister)
2. Low CO₂ pressure. You will find atomizer impossible to be used with DIY setup.(unless it’s the high pressure DIY CO2 canister)
3. Inconsistent CO2 releases. Sometimes when I leave my house, it is doing a respectable 4~5 bubbles per CO₂. But when I got home, it is doing maybe 1~2 bubbles per second.(unless it’s the high pressure DIY CO2 canister)
4. Need to replenish the bottles and it can get a little messy sometimes (but much easier than yeast/baking soda formula)(unless it’s the high pressure DIY CO2 canister)
5. Higher running cost in the super long run. (unless it’s the high pressure DIY CO2 canister)

The high pressure DIY CO2 Canister has non of the inherited problems of the two bottle system

Find out more about High Pressure DIY CO2 System

After researching online for days I settled for a DIY CO₂ kit that is quite popular on Aliexpress and Amazon. Cost just around US$21 delivered to where I live from Aliexpress.

The single greatest advantage of this kit is you can actually shut it off at night! It will not explode like the yeast + baking soda recipe. In addition, the reaction is immediate. Squeeze the bottle, vinegar got pumped into baking soda, and you get CO₂ and pressure build-up immediately. No need to wait for fermentation.

There are cheaper variants around but I settled on this because it has a brace that can secure the soda bottles so it is easier to carry around when doing maintenance. And it looks much cleaner.

The kit came with all the tubes attached so there is really nothing else to setup. The only thing you need to do is to screw the soda bottles in and attached the outlet tube to the kit and to your bubble counter/diffuser.

Additional items that you MUST purchase:

• Ceramic diffuser,
• Bubble counter,
• Check-valve (some bubble counters comes with it)

Citric Acid or Vinegar

There are a few instructions on how to setup a citric acid/baking soda recipe. I read through every one of them and then I hit a road block. From where I come from, citric acid is not available, or at least not conveniently and in small packing.

One of my mates owns a chemical company and the smallest pack of citric acid powder is a 25kg pack. My wife will kill me if I store that at home.

So I went online to search for alternatives. There were several websites that stated that vinegar can be used in place of citric acid. But none of them stated the ratio one should need. Some even suggested mixing vinegar with water. And none of them actually states what kind of vinegar to use.

So I decided to do a trial and error with vinegar/baking soda recipe. And it worked! And the results were great!

Here’s the recipe:null

Baking Soda 400g +
Man-made/artificial vinegar 1L

That’s it!

You do not need to mix the vinegar with any water.

You do not need to mix the baking soda with water as well!

The cost is well under US$3. The 400g baking soda cost me just US$1.30 and I purchased a 5L white vinegar at my local supermarket for a mere US$4. My latest mix has past 10 days and I predict it can surpass 15 days, no sweat. If I increase the baking soda to 800g I am pretty certain it can last 1 month.

Singapore Reader Note: So far I discovered that only Giants @ Vivocity sells the 5L white vinegar. You can still get the 3L pack from a reasonable size Giants. The smaller Giants are only selling small bottles.

How to set up

You will need to get two empty soda bottles. I am using 1.5L bottles. They MUST be from soda drinks. From what I learned, soda bottles are manufactured to withstand higher pressure than your normal non-carbonated drinks.

1. Pour 400g of baking soda powder into one bottle. No need to mix with water. Just raw powder form. (Okay, 400g maybe too much! 200g~300g will be perfect.)
2. Screw the bottle containing the baking soda into the socket with the tube that DOES NOT have the ball-head. Make sure it is tight. Be careful not to over screw and risk damaging the threads.
3. Pour 1L of vinegar into the second bottle. You can adjust the amount of vinegar according to your bottle size or needs. BUT DO NOT FILL MORE THAN 1L or you will cause the baking soda bottle to be overfilled later on, and the vinegar/water mixture will end up being pump into your tank!
4. Screw the bottle containing the vinegar into the socket with the tube that has the ball-head. Make sure it is tight as well.
5. Attach one end of the long tubing to the outlet that is on the screw valve.
6. Next, estimate how long you will need to run the tube from your bottles to the tank. Cut off the excess.
7. Then cut the tubes into sections so you can connect your check-valve, bubble counters, and diffuser.

How to Start the reaction

Once everything is connected you are ready to start the reaction.

1. Make sure the outlet valve is open. Then give the bottle with the vinegar bottle a really hard squeeze.
2. When the vinegar touches the baking soda powder, the reaction is immediate!
3. You will need to give the vinegar bottle a handful more squeezes before the reaction can be self-sustained.
4. Once you see vinegar started flowing without your intervention it is time to shut the valve.
5. Now let the pressure build up. Keep squeezing the vinegar bottle until you cannot squeeze any more. Yes! That’s how much pressure we need to build up. I would take a break and come back again later.
6. The pressure gauge is a bit tiny and I have trouble reading it under dim light some times. Getting old. At 1.5 reading you can slowly release the valve.
7. If everything went well, you can see the diffuser fizzling immediately.

If even after releasing the valve all the way until it came out and there is still nothing coming out of the the diffuser, DO NOT PANIC!

Troubleshooting method #1

Sometimes the reaction is not sufficient. Unscrew the bottle containing the baking soda SLOWLY but not completely. Keep unscrewing slowly until you hear gas escaping hizz. Immediately vinegar will be drawn into the baking soda bottle resulting in more reaction and more CO₂. Screw the baking soda bottle back immediately.

Troubleshooting method #2

The DIY CO₂ pressure is kinda low for some check-valve. Loosen the check-valve. Keep loosening. And then you will get a rush of CO₂ into your bubble counter! The feeling will be tremendous! Lol.

If your bubble counter comes with check-valve, loosen until water starts to leak from it. Then gently tighten it until there is no more leak. If there is still no movement, use your finger to give the bubble counter a good knock.

I will try to upload some videos later on. Let me know if this works 😉

I have a new HIGH PRESSURE DIY CO₂Canister. Check it out!

It is still the same old 200g Citric Acid powder + 200g baking soda formula. In fact it is even more simple.
You simply pour in all your ingredient and water into the canister all at the same time! Screw on the regulator and tada! Instant CO2. No more priming.

Citric Acid Gone Over Night?

Well when you woke up to find your citric acid solution gone over to the baking soda solution bottle overnight it usually means a leak has developed. The most likely culprit is the rubber O ring was torn and could not keep the CO₂ trap.

Unscrew your bottle and inspect the transparent O ring. This O ring is extremely fragile and can tear when screwing your bottle in. It can also becomes dry and disintegrate easily when exposed to citric acid.

Remember to always rinse it well during every bottle change, or best if you can soak it in water.

Use a Reactor

If you want to make your CO₂ last a few more days use a reactor! The working pressure required by a reactor is also much lower.

[Update 15 May 2017] Added video of my setups.
[Update 13 Mar 2017] Well, I have moved the DIY CO2 kit to my 75 gallon tank and changed the ceramic diffuser to a larger one and the results were amazing. Currently I am doing about 2 bubbles per second because I am cycling the new 75 gallon tank and I want to keep the pH level high to encourage bacteria growth (they need about 7.5 pH).
 The maximum I tried was like a billion bubbles per second! Too much to be counted! And pH dropped from 7.5 to 5.8 @.@ and I was getting off the scale nitrites reading (nitrite eating bacteria shutting down). And the bottle of vinegar was depleted within 2 days.

[Update 17 July 2017] I have a new HIGH PRESSURE DIY CO2 Canister. Check it out!

[Update 28 October 2018] I am no longer using the kit due to broken O ring. I have switched over all my kits to DIY CO2 Canister. It is still the same ingredient but you get much more higher pressure.

Check out my commercial CO₂ reactor review here.