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Added DIY CO2


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started to add DIY CO2 to the 40L tank i have just set up.

2L bottle

current mix is

2 cups sugar

2 teaspoons yeast

1 teaspoon bicarb soda,

used bicarb to get my KH up to 4 and am currently monitoring PH level to see how far it drops

first pic is 2L bottle and a make up bubble counter


didn't like the size of this so did some googling and came across a syringe bubble counter so made one today.


not quite as per the site I found but I am seeing how it goes, no glue or silicon used, I heated the end of the syringe and forced the check valve in, seems to be holding with no leaks I will have a check valve between this and the tank also so worst case it if fails I will lose the water in the check valve and maybe some CO2 but it wont drain the tank.

pic of the current bubbles in the tank, no diffuser yet so am using an old air stone


I am going to empty the water from the first bubble counter(baby bottle) and use this as a gas separator as I also came across that design on the net.

Will be looking for a diffuser and drop checker

will play around with the mix to see what gives the best CO2 amount and longevity. I am currently getting 2 to 3 BPS but no idea how long this mix will last yet.

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I find the DIY bottles last about 10 days. Come on... now show us some pics of the plants pearling. :)

no pearling yet, I only have low light though so that may be somethning I need to step up.

also a little worried about nitrates too, the tank has none the plants must be soaking it all up so I may need to start dosing this before I get any problems.

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I thought no nitrates would be a good thing. Why are you worried?


My understanding (from web searches only no experience with planted tanks) is that low nitrates are great in fish only tanks but not ideal for planted tanks, the plants use nitrate as part of their feed/fertilisation. Everything I have read seems to indicate 10-15ppm is where it should be in a planted tank.

If the plants are using all the nitrate available and then running out it will stunt growth and possibly lead to blue green algae which can come in to tanks with no nitrate, the other concern too is if the nitrate is used up the plants will stop or slow down meaning they would not absorb the other nutrients primarily phophates. This excess phosphate then feeds black beard algae.

Today I noticed what I think is black beard algae on the moss so maybe adding nitogen is what I need to do

This is really my first attempt at planting a tank so any one with more experience please feel free to correct any of the above comments in they are incorrect


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Guest happyjack

Using a DIY setup on my tanks. I use a 2lt. coke bottle bu I only use 1/2 teaspoon yeast and 1/2 T/s. baking powder. with 2 cups of raw sugar. This mix is still going at 4 weeks but change them at 3. Dont worry about buble count. It doesent seem to make any diference.

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Very nice! The bubble counter is fantastic! If you don;t have one somewhere in the line, you may want to install a safety valve. Too many fishkeepers have had a whiffy alcohol shower when the tubes on the DIY CO2 clogged. :) It is also a good idea to weight it down somehow (in a bucket with sand in the bottom or strapped to the stand leg or something as tipping them over is almost guaranteed to clog the air line and they tip fairly easily.

Are there fish in there? How far did your pH drop when you started and are you blowing off the CO2 at night?

My very basic understanding of CO2 is that you really do need the nutrients and extra light for it to be effective, so dosing is probably a very wise idea. It'd be good to know what you are low in and what needs adding as you need to balance those nutrients to avoid the algae issue. If any of your LFS have the facilities to run a full water test for things like iron, potassium, phosphate etc, I'd get that done on your tank water and your tap water, so you have a starting point where you know what your source water is missing and what your tank water is missing/has (substrate etc can change it in the tank)

I'm a little surprised you are seeing BBA in there, I always thought that it was one of the types of algae that you could 'suffocate' by using a source of carbon, but perhaps it has a break point and before that it just grows like mad :)

Planty things aren't really something I'm good at, it all got a tiny bit too scientific for me.

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if you cut down on the amount of yeast used your output while weaker will last longer. i usually use 1/4 teaspoon while you used 2 teaspoons so your batch probably wont last very long.

I made the first batch to test and didn't really check what I should have used in regard to qty just went from memory, I did make it a bit strong and have made a new batch today with 2 cups sugar and half a teaspoon of yeast as per happyjacks mix

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Hi Callatya

good idea on the safety valve, might have to see what I can do.

heaps of fish, actually have overstocked it trying to get some nitrate reading.

40L tank now has

7 neon tetra

5 glowlight tetra

2 kuhli loach

3 guppies

PH dropped by around 0.4 from 6.8 to 6.4 and I undo the bottle top to let he CO2 escape overnight

will be purchasing test kits for iron and phosphates soon, have not seen any for potassium though.

BBA - I only think it is not sure what it is yet but I have been double dosing excel the past coulpe of days

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