this is particularly for Layne and anyone else that is interrested in making their own DIY co2 setup for a 10 gallon tank.

this is a setup i devised for my own 10g tank that worked well and allowed me to have lots of healthy plants.

equipment needed is as follows ...

2 litre plastic bottle
6 x 4mm airline tubing
1 air stone
1 stop valve
1 plastic airline connector
strong glue
1 glass tumbler
2 small cups of sugar
1/3 teaspoon of yeast
bicarbonate of soda
pH test kit
KH test kit

method ...

take the lid of the plastic bottle and make a small hole in the top centre of the lid. push the airline connector in and glue it in place with strong glue like epoxy resin. once glued. airline tubing is connected to the bottle and fed into the tank. on the end of the tubing that goes into the tank is the airstone. the stop valve is positioned on the airline between the bottle and tank to stop any water feeding back. above the airstone, u place a glass tumbler at an angle (see diagram). the tumbler needs to be held down. i found a couple of rocks was a good way of doing this (see diagram). next to the upturned tumbler is the output of a filter unit. an internal box filter upside down works well for this or if u have an external filter position the output pipe next to the tumbler instead.

inside the 2 ltire bottle is a mix of water, 2 small cups of sugar and 1/3 teaspoon of bakers or bread yeast plus a small pinch of bicarbonate of soda. the mixture needs to be no hotter than 30C or less than 10C in temperature or the mix wont brew properly and produce the co2.

without explaining the science there is a little more work to be done before the micro brew (2ltr bottle and mix) is connected. the tank needs to have a KH reading of between 3-6 degrees. this stops the pH falling and rising (swings) during the night when the lights are out. pH swings can harm and in extreme cases kill fish. using a test kit and adding bicarbonate of soda to the tank water, if necessary, the tank's KH can be set at 3-6 degrees. for example my tap water is very soft and has practicaly no KH so i find if i add 4 grams of biacarbonate of soda per 10 gallons of water i then get a KH reading of between 3 and 4 degrees. if one is using hard tap water u may only need to add a smaller amount of bicarbonate of soda or maybe none atall. ofcourse everytime a water change is done care needs to be taken to add water that has has the same KH reading. with my very soft tap water this means i add 1 gram of bicarb per 25% water change (2.5 gallons).

once the KH is set the micro brewer can be connected. when a fresh bottle of mix is added, it usualy takes between 2 - 8 hrs for it to start brewing (producing co2 bubbles) depending on the room temp and the temp of the bottle. i usualy add mine at night time and it is started by the morning. when the brew is working bubbles of co2 will come out the airstone in the tank and co2 will gather in the upside down tumbler. the brew will produce more co2 than the tumbler will hold, especialy at the beginning, but this is ok as excess co2 will 'burp' out of the tumbler which is placed at an angle to allow this to happen (see diagram). the co2 in the jar will slowly dissolve into the tank without any help but to help it and to make the sytem work and be more efficient a current of water is run along the bottom of the tumbler where the co2 meets the water. this is what the upside down filter or external filter output is doing (see diagram).

basically that is it. the micro brew mix needs to be replaced every 2 to 3 weeks, once it stops producing enough co2 bubbles to keep the tumbler full.

to make sure the system is working ok and producing co2 plus to be able to work out the level of co2 present in the water a pH test kit is needed. again without explaining the science, if a pH reading and KH reading is known then with the help of a table or online calculator the co2 level in the tank can be determined. idealy if the co2 in the tank is atleast 10pmm and no more than 30ppm then the plants will benefit greatly, which is the whole point of making the DIY co2 . as an example my co2 injected tank at the moment has a KH reading of 3 and a pH of 6.6. when i use an online calculator my co2 reading comes out at 22.6 ppm which is almost ideal and means my plants are getting plenty of co2 to help them grow.

the following link contains a very good co2 calculator and also has a chart too that can be used to work out the co2 level using the known KH and pH levels.

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apart from adding some 'liquid plant food' now and again this is all that needs to be done to run a homemade co2 system. if it all sounds a bit complicated or too much work then obviously DIY co2 injection is not for u. otherwise this is a very cheep way of doing it and no more complicated than using a bought co2 system i would argue.

this system, with the tumbler works well for a 10g tank i found, but i would mention that if one is to use a DIY co2 system on a bigger tank as i now do, u realy need a co2 diffuser instead of the tumbler as the tumbler alone wont dissolve enough co2. i will maybe do another post later showing the homemade diffuser that i put together for my 40g tank.

finaly here is a diagram i made showing the DIY co2 setup, followed by a pic of my 10g tank when it had injected co2 and lots of plants

Thanks! this is much nicer than buying a system...I can spend the money I saved on something else! lol

well, I have started to collect the materials... namely the two liter bottle (pop!) and some other stuff... I won't be able to get it together right away (busy weekend), but when I do, I will be sure to report back here!

good luck, any probs or questions post them here or PM me and i'll try to help the best i can.

Very good, Nick! A couple of nice looking rocks you have there (all the Girls say that!) in your 'sketch'.

How fast is that current you have running under the tumbler?

I don't know if the airstone would really do much more than anchor the tube in place, in that configuration? My tube is open ended into my Bubble Maze, and it just pops out a small bubble every few seconds. I would like to see your homemade diffuser.

Are you going to mention the 'Horrors' of DIY CO2?

yea, i'm quite proud of my rocks

"How fast?" - hard to say, enough to churn the water around the bottom of the tumbler and help the co2 dissolve. so ... fast is good but not too fast as to empty the tumbler before the co2 is dissolved. if the flow is too slow the co2 wont dissolve enough. initialy i used an upside down fluval 1 which worked, later i used the input from a fluval 204 external filter which worked better.

u r right about the airstone, it is only there to hold the tube in place.

i cant realy think of any 'horrors' but i was gonna mention that u can get an odd build up of white to yellowish 'gunk' around the airstone which i believe is a yeast residue. i didnt bother with it as my khuli loaches, tiger loach and bristlenose liked to munch on it and it didnt seem to do them any harm.

i am going to make a new thread to show off the DIY CO2 diffuser that i now use. please check it out.

I was thinking of the joy's of exploding Fermenters, Yeast squirting into your tank, tanks draining, and such. Perhaps noting that Carbonic Acid dissolves some types of one-way valves?

My daughter alerted me to the tank going 'cloudy' one evening. I'd put in a tad too much yeast, and the froth was going straight up the air line! We were lucky, we caught it very early.

I might have to play around with something like this after I get my tanks sorted. I've not had a properly planted tank for ages, and once the rack is built I'm looking to put my existing 36x18x18" under a 48 or 60x18x18 and setting it up to be a nice natural looking tank, probably with some discus to grow out ahead of the fish house project coming soon(tm).

i admit i probably make a few assumptions. using a soda type bottle and the mixture i recommended shouldnt be in danger of exploding. i was going to mention that there should be a 3 inch gap left at the top of the bottle but i hoped people'd get that from my diagram. i also assumed that people would make sure the one way valve was pointing in the right direction, away from the bottle. the valve ofcourse being the thing that stops the water syphoning out the tank.

i didnt know that some one way valves could be dissolved, touch wood mine have been ok.

My Secondary School Science Teacher used to always say "The thing about Common Sense, is that it's not very common!"

I think your assumptions are fine, but some of your readers might get a bit enthusiastic, eg. 'Lets triple the yeast, and see if we can get a few more weeks out of it!'

Monkeh's going for a Fish Shack! I'm thinking I should move back to the Farm. I've got a 10 x 20 ft shed back there, that I built when I was at school. It was for all my electronics crap, and the Slot Car Set (6 lanes, vrooom!). I could could pitch all that stuff out, and put in a few racks. It's right behind the rain water tanks, so I could have it all 'on tap'. 400km from a decent Aquarium tho'...

i'll have the slot cars set (scalectrix?) if u r throwing it out, lol

i used to have a great set when i was a kid, with tons and tons of track. not a 6 lane one tho, and i wish i never gave it away