• #41
I found a step by step for a way to make one earlier today

probably going to be fairly similiar!
  • #42
Yes it works very well. I used the hard plastic tube from a undergravel filter it about 1/4" wide drilled hole through cap one in the one for the regerator and 2 for the 20oz bubble counter here is a pic of the double tube cap, just watch when u silocone the inside of the cap use a Qtip to make sure there is no silocone where the bottle meets the seal. Also when you drill out the cap drill through the side with the seal which has the threads.

I will get you the dufusser soon
  • #43
There's a cheap DIY CO2 reactor I just assembled today, following easy instructions courtesy of Nikolay (Niko) at Aquarium Plant Central DIY sub-forum, it has 14 pages but worth the reading:

Santo Domingo
  • #44
I did this too and worked very well.

I recoment the 2nd bottle to stop the mix bubbling up the tube towards the tank.
- I learned this the hard way.

Although the fish will just eat it!
  • #45
Got a ? does it matter if you have the reactor or diffuser in the tank with the plants or can I put it in my sump with the rest of my gear?
  • #46
It's best if it's in with the plants. Water turbulence provides a chance for gas exchange, which will try to even out CO2 vs other gas ratio.
  • #47
A couple questions here:

1. Does this run all the time? If so,why have it run at night when no photosyntheseis is taking place. I heard photo. only happens during the day when the lights are on.

2. Would I still be able to have an air stone running in the tank or would it just negate the purpose of CO2. I noticed when I shut off my air stone all my fish were hanging around the top of the tank. When I turned it back on, everybody was back to normal.

3. Why the use of the powerhead. It looks as though it's just holding the tube in place.

4. Whats the mixture,1 teaspoon of yeast,2 cups sugar and how much water?

Told you I had a few questions,lol

  • #48
1.Yes it runs all the time but with only 1 bottle on a 75gal tank the nightime build up is quickly used uup in the day time AKA lights on time.
2.I run and airstone all day and the plants are growing like crazy so I don't think the airstone hurts the CO2.
3.Used the air intake on the powerhead to churn up the CO2 into tiny little bubbles anything left gets traped inside the tube and the churning of the powerheads waterflow makes about 100% sateration into the water.Going to make the tube shorter though but works nicely.
4. I do 1 1/2 cups sugar, 1 teaspoon baking power, and 1 teaspoon (or 1/2 a pack of Red star yeast about the same) I add 6 cups of warm water with the sugar then sake until sugar is disolved the add yeast and BP to it I stop the water where the top starts to curve the the spout. shake and wait for bubbles about 1hour. last about 2 to 3 weeks.

Hope this helped you out there a bunch of good info on check it out or just shoot me more ?.
  • #49
Thank you Hop, I just happened to do 1 today just to experiment. I only used the 2 liter bottle and had bubbles within hours. Why the use use of the smaller bottle?

I also had to use the yeast cake as my wife got the wrong kind and it's working.

I just ordered 2 under water minI filters from Petco,these are the ones that go inside the tank for the reactor, Seen that from Niko on one of the sites up above mentioned.

I'm just testing this out in my 20 gallon tank that has nothing but feeder fish in it and see how they do before I attempt to place this in my 120 gallon.

Does useing this co2 have any affect on the PH in a tank.

  • #50
The small bottle works as a bubble counter and CO2 seperator. You can do without it. I am currently running without it myself. The bubble counter is just so you can see more easily how much CO2 per second you are injecting. Also, sometimes the yeast mixtue can make its way up through the tubing and the small bottle keeps it out of your aquarium.

I am running this setup on my 120 gallon now. It takes quite a bit more CO2 for a 120 gallon. I am currently running 2-2liter bottles. I believe I am going to use 2 large bottles I have from my kids hawaiian punch. Its about 6-7 liters instead of my 3-4 currently. Any little bit helps though. Even with only 2-2liter bottles, I can tell a difference.
  • #51
Thanks Ghostfish, I can't wait to try it in my 120. Lights and plants arrive tomorrow. Been here all night moving the silk plants out and moving all the large rocks I have for the numerous caves.

Think there's a way to hook up 1 of those small filters directly from the 2nd bottle to a 5foot air line?
  • #52
I am not sure. I am sure there is some way. You just never know how effective it will be. I am pumping my CO2 straight into the intake of my canister filter. It works very well. I am going to redo my entire setup though. I keep getting leaks on my connections to the 2 liters.
  • #53
Ya the second bottle is a bubble counter/gas seperater and would go without one it helps tell you when the yeast needs changed and all so just in case the 2 litter overflows it go there instead of your tank. The last thing you want in your tank is yeast so I've been told. Good luck with the setup and post some pics of your plants and reacter setup.
  • #54
my mixture only just made it down the tube to my tank and it did not upset things too much.
It looked a little funny coming throughthe air stone like a stringy mess - The fish just ate it. Seemed to enjoy it actually.

  • #55
I I am pumping my CO2 straight into the intake of my canister filter. It works very well. I am going to redo my entire setup though. I keep getting leaks on my connections to the 2 liters.

I would think twice on this. CO2 could damage pump impeller in your canister filter; indeed it will damage the impeller of the DIY diffusor/reactor but it costs barely nothing to replace it.

I don't use silicon to seal leaks since it doesn't work well with the soda plastic caps, I use mechanical means to seal it: smaller holes, tightly fitted tubes, and teflon tape if needed be.

I attach the plastic check valve, with a piece of hose (use CO2 safe if available) around it, on top of the soda cap.

I also attached (using hot water to soften) a plastic syringe to the output check valve from the 20oz gas separator bottle. I fill it with water so it works as a bubble counter. For illustration purposes, I let water go into the output tube/hose line so you could see the bubbles going up.

My dissolved CO2 remains within the 20 to 30ppm.

I replace one bottle, no matter what every week.

It runs 24/7 unless I have an emergency (e.g. like using meds that might lower dissolved oxygen, as I had to recently due to an out brake of ick: I pulled the system out at nights for three nights the day I added medication-unplugging one check valve- and also diluted the mixture -half usual ammount of yeast- to make the level of dissolved CO2 drop to 10 or 15ppm).

Santo Domingo
  • #56
Ya was going to do the same but took the cheap way out for my caps it is better to buy the right fittings. Thanks for the impeller info but it won't hurt my powerhead the intake for the CO2 is after the impeller on the neck of the outflow of water so the co2 breaks up into micro bubbles by the curning of the water in the tube not by the impeller itself working making mine smaller will update as soon as I make it.

Ohh ya nice set-up too
  • #57
Well ended up making 2 of these for the 120 gallon tank. Attempted to use the Elite underwater filter for 1 of them and it did'nt work as well as Niko's pics showed.

So I trashed that idea mighty fast. I did end up placing 2 bottles with each one and added a ceramic diffuser to the ends.

Now here's the result; After about 6 hours(was napping) my wife waking me up saying all the fish are dieing. I immediately went over and loosened up the caps on the bottles to shut them off and turned on the airlines. My PH is normally 7 and when I immediately tested the water it went down to 6.2. I'll get back to this later.

Well 3 catfish dead,1 of them was 1 that I caught this past summer when looking for bait in our river here. When I caught him under a rock, he was no bigger then 2 inches(channel catfish). The other dead one was the algae eater. The only bottom fish that survived were 4 clown loaches and the big pleco.

My 4 Discus were all on there sides along with the 5 Angels. Had to actually pull them back and forth by there tails to get them moving and place them near the airlines for oxygen. I also did a 80 gallon water change. They survived and are doing quite well.

I have'nt used any CO2 since this happened. Now my normal readings are;


Why did this happen? The dramatic PH change and the CO2 sucking all the oxygen out of the tank?

With the chart I have here it says that my co2 is 11.8 with my PH and KH readings and 18.7 and 30 is good for plants but in order to get these readings my PH would have to be 6.8 for 18.7 and 6.6 for the 30ppm..Not sure if I want to put the fish in this situation again.

Does this mean I have do drop my Ph as its the last thing I am going to do? Is there any type of test kit for co2 readings besides useing the PH and KH or anything that can notify me of dangerous levels??

In other words my co2 reading according to the chart was 75 and not even close to being between 18.7 and 30..


  • #58
I was told with my 75gal that 1 bottle couldn't crash my PH so with 2 bottles on a 120gal you would think it couldn't happen. The only thing that I can think of is that you used 2 diffusers at the same time so there was 2x the CO2 being disolved into the water at the same time which crash your PH. So I would take 1 out tie the 2 bottles together run that to a gas separater/Bubble counter then to one of the diffusers. API make a test kit it is the Reef Master Kit it has every test you will ever need. Sorry to here about your fish. You have just had a PH crash PH should never move more that 1 point at a time. The CO2 causes the water to become acidic and lowers PH. When you add to much co2 at once you will have a PH crash and this burns the fish. If yu decided to start it back up run your air stone with it, watch the PH the first few days you can even buy a PH tester that stays in the tank to monitor it for you.
  • #59
Oh well,you learn by mistakes. Only useing 1 from now on. I left the air on the one side of the tank today with the co2 running on the other side,not a problem and as a matter of fact, a no swing in the PH iat all for 8 hours. I now have all the air on,this is an additional 4 foot air hose that runs under the gravel where the co2 is.

Going to give it a go tonight after lights are out and see what happens. And yes I did have 2 of them going that day when heck broke out.

Is there a shut off valve that'll go on airline?? And if this pleco keeps ripping the moss off these rocks and wood, he'll be mounted on the wall,lol..

Right now I have all the Angels battling it out, reckon it's time for egg laying.

I'll keep you updated on whether this is going smooth.

  • #60
you don't want to add a shutoff valve the problem with that is the pressure will build up in the 2 liter and boom yeast water everywhere. I run mine 24/7 without an airstone. Let me know how the plants do and keep an eye on the PH.
  • #61

sounds like a good setup I have been thinking about doing this 4 about tree months but wasn't sure.... still not...... 1 question and it is wat is your lighting like I the aquariums. that's my only feer. I will put the co2 in there but I'm not sure with my lite if it will besufficent to photosynthesis to occur at the level lite I have.
my light is 20 wat floro-glo in a 29 gallon tank.

plz reply
  • #62
The CO2 will still help your tank but you will want to add 1 more 20watt strip light or buy 1 2x20watt fixture there about $30 bucks. You want to be over1 watt per gallon but under 2watts mine is 1.24watts per gallon.

Ohh that's for low light plants.
  • #63
Well it's almost 3 in the morning here and everything is calm, the PH,KH and all the fish with the co2 and all air lines running. No change..PH 7.0 and the Kh still at 4

Hop these are all new plants,so I can't tell if it's helping or not. All I know is that this is the longest plants have ever stayed green in the 120. Usually it was 2 days and bye-bye. So I guess it's working.

With 256 watts of light and now with co2 they better be,lol.

As for the shut off,I get your point. That would be just the classic, a co2 explosion,lol. For sure it would smell like a brewery.

One other time that I had plants were in the quarenteen tank (20 gal.) with 15 watts of light and the plants were unreal. The Amazon swords got so big that I had to move them to bigger tanks just to pick rotting leaves floating all the time. I got sick of that and just yanked them.

So as far as I can judge this DIY it gets a high 5 from me.

  • #64
Hey Hop,

Everything is running fine now. Running 2 at a time all the time. I keep the air stones off during the day and just turn them on at night.

Even after that dreadful bout with almost killing all the fish,my Discus have started spawning finally after 2 years. At least once a week now after a nice water change. There 0-2 so far for any living juveniles. Maybe that sparked some love in them,lol..

Did have a problem with algae on the glass and on the plants, ended up getting 8 little oto's and there taking care of that.

Now I have 2 rena xp3 canister filters here and I ended up hooking up 1 of the co2 hoses right in front of the spray bar and it ends up shooting tiny bubbles everywhere. The other one is still being run by the ceramic diffuser. These Rena's have a control valve on them ,where you just pop off the button and bingo you connect the co2 hose right there without it even going into the filter.

As far as the plants, I 'm having a hard time keeping up with trimming them. I got 1 hornwort plant here and I have to trim at least 10 inches off every 3 days or so. I just keep replanting the trimmed pieces and I have at least 1 foot of nothing but hornwort jungle. I just started placing the other trimmings in the back of the aquarium,lol. Great place for all the occupants in there to hide.

Well just thought I'd keep you updated and everything is running fine. I was looking at 1 of those complete co2 systems,heck, I'd be broke for sure. But then maybe the govt. bailout would extend for one of those systems,lol..

BTW the other plants are doing just fine. Thanks again

  • #65
ewolfe glad to here eveything in going good. I know what you mean about the Hornswort mine is growing like a weed. Going to order my complete system this week going to put the DIY on my 29gal I'll post pics of the install also adding and aglea scruber to my sump. Ohh ya you might want to try so liquid fertalizer I'm using Sea Chem Florish and if I have and algae breakout in the tank I add Sea Chem Florish Execl great for plants but kills algae of all speicies. Good luck post some pics up of your plants.
  • #66
OK I have a Question... I have a ten gallon tank and a 2.5 gallon tank (that I'm going to be running CO2 to both tanks with one system).. should I make the mixture smaller or is it ok to put

1 cup of sugar
1 teaspoon of yeast
A pinch of baking soda

in a 1 litter bottle filled two about 2 inches from the top with water... or will it kill the fish? Because i've read some about this and most are in 20 gallon tanks.
  • #67
Dwarf PM I would cut the mixer in half to start or use a 2litter bottle run that to a gas seperater than a check valve then T off to both tanks. If you wnted to you can get a inline regulater little plastic thing with a valve nob on it inline with the smaller tank so you could send more CO2 to the bigger tank I think they are for airlines. Just a thought.
  • #68
Just wanted to say, I put together a 4L system for my 29gal and a 2L system for my 10gal last weekend. The plants in both tanks have definitely shown increased growth, with the plants in the 10gal going absolutely crazy (the bottleneck in the 29gal now is light). I have anacharis in the 10gal that's grown more in the last week than it has the last couple of months.

Was going to mention that I was using a couple of those in-line regulators that hop2jr is talking about myself, and it turns out they aren't anywhere near airtight. At least mine weren't - the only reason they work for pumps is that the pump is putting out a ton of air compared to the DIY CO2 system.

Also, to Andrew, I don't think splitting one system to two tanks will work. The CO2 will probably all go to your 2.5gal, but none of it will get to the 10gal since there'll be more pressure on that side of the line.
LC Scotty
  • #69
Tubing seal

I've read here that folks have trouble maintaining a seal with the tops of the 2 L bottles. I decided to go threaded when making my first CO2 reactor.

The problem is that the smallest threaded fitting is too large for a typical 2 L pop bottle. However, a 2 q juice container (Welch's grape in this case) is much wider. So I went to Home-D and picked up an "Ander-Lign compression connector" for 1/4"od to 1/8" MIP. Basically, it has a threaded body-one side is 1/8" pipe threads and the other has threads that are part of the compression fitting. All you need is the body, you can chuck the ferrule and compression nut.

Then I went over to the lighting section. It turns out that the washers and nuts used in various lighting fixtures are pipe threads (yeah, I was surprised too) so I picked up a locknut and washer kit. Total cost at Home-D? About 3 bucks.

So, now I drill a hole in my cap, put one lock nut on the pipe thread side (pipe threads are tapered, for this connector it was the side of the body with a longer threaded section), seat that against the outside surface of the cap and then screw the other lock nut on the threads that protrude to the inside of the cap. Alittle bit of silicone to seal it up and away we go.

Basically, I think any 1/8 pipe nipple and two of these lock nuts will work. The end that the tubing will attach to will be too large for airling tubing, but a short piece of tygon and some barb adapters will get you down to the right size.
  • #70
Hey thanks for the info... I used a 1 liter bottle with another 1 liter bottle with water in it as a bubble counter and so if the other bottle over flows it doesn't go into my tank. And also I have decided not to run CO2 into both tanks..

Thank You.
  • #71
So I would love to upgrade to a co2 cylinder but until I get some $$$ for such an investent heres where I stand. I have 2 DIY co2 injector systems placed in my aquarium so that the tiny bubbles are sucked into my canister filter. I have it kinda on a schedual I started last week heres what I do: diffuser 1 is mixed and in action.. diffuser 2 is mixed 3 days or so after when diffuser 1 starts to dwindle in bubble production.. So its like 1 is really pumping and the other is 50%. I'm guessing its doing its job, all my plants are really flourishing. Except for my moss- Iv had for about 2 weeks, still thriving though! It really is tough to measure co2 without a bubble counter/co2 guage ect. Any 1 else with experience use multible DIY diffusers like my setup?
  • #72
I think you mean multiple yeast generators rather than multiple diffusers but that's niether here nor there. I run all my DIY co2 rigs with multiple generators so that I can have a more consistant supply of co2. Depending on the recipe you use you will probably find that when you first make up a mix, it will produce large amounts of co2 for a few days before settling down into a more normal supply for 10-14 days & then it will start to taper off slowly until there is no more bubbles being produced. Assuming a mixture produces for 14 days before the bubble production starts to die right off, You would make a new mixture in alternating bottles every 7 days. That way you are getting close to the full life out of your mixture while keeping the supply of co2 fairly consistant.

You can make a bubble counter out of a small coke bottle or the like. Just make it up the same way you would the yeast generator, except put two holes in the lid. Put the co2 line from the yeast generator through one of the holes & pull it right through so that it will extend close to the bottom of the bottle when the lid is put back on. Through the other hole in the lid you put your co2 line that goes to your filter. TrI'm that line close to lid just like you did with the generator. Fill the small bottle half full with water & put the cap back on it. You will now have the co2 line into the bottle under the water allowing you to count the bubbles as they come from the generator. The other line should be well above the water level in the bottle & will carry the co2 to your diffuser, (filter).
  • #73
I'm trying to make sence of your bubble counter.. hahah I have to think it through or see a diagram
  • #74
I found a helpful video on youtube. maybe il try it tomorrow, looks like another blizzard so far! I should have all the time I need while I'm snowed in tomorrow and I also need to look into check valves. my co2 generators are above the tank so I'm not so worried about draining my tank or anything but would it be smart to stop the bubbles at night when lights go out. ( using some sort of check valve if I can find 1) Keeping in mind I don't want my generators to explode!
  • #75
Much easier just to leave the co2 running 24/7 & have an air stone running when the lights are out to avoid large PH fluctuations & possible oxygen shortages. A timer on an airpump makes it nice & easy. Check valves are usefull on co2 set ups but in a different way. If you have multiple generators that all run into one airline going to your tank, put a check valve on each individual line between the generator & the place where the lines merge. That way when you need to make up a new yeast mix, you don't lose pressure through the whole system & the other bottles can keep pumping co2 into the tank. Here's a link to someone else's thread on diy co2: Scroll down the page a bit & you will see an entry from me that has pics of the bubble counter/sump arrangement & the placement of check valves on the system.
  • #76
that's also a good point Id rather run the co2 generator 24/7 to avoid ph fluctuations. I'm still gathering info on how to build my bubble counter, still confusing I need a pic or a diagram. also what is the best way to add co2 into the aquarium? straight into the canister intake like iv been doing? It seems like the most benificial way to go about it but is there a better technique? thanks guys!
  • #77
Running the co2 into a canister filter or internal filter works pretty well & is what I do on most of my tanks. You can buy proper diffusers but many of them are not that great. I've tried a few different sorts & havn't come across one that I'm hapy with yet.

Bear with my poor skills using Paint. Here are a couple of very basic diagrams of a diy bubble counter & a diy inline CO2 diffuser. The first diagram is the bubble counter & shows the principle only. You need to apply the idea to a small bottle. The second is the co2 diffuser & is fairly self explanatory & goes inline before the canister filter. Most people put them on the outlet side of their filter but I find mine works best on the inlet side. Sorry I'm without a camera at the moment so I can't take pics of my arrangements.


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  • #78
I think I got this but I have 2 generators. Is it possible to connect them both to one bubble counter? Diagrams are very helpful, post them up everyone!
  • #79
I jus saw a bubble counter made out of a seringe it looked pretty cool
  • #80
If you click on the link I provided in post 5 of this thread, it will take you to another thread. Go to post 6 in there & you will see my diy rig along with close up pics of the bubble counter that I use. There are 3 lines in the lid of the bubble counter bottle. 2 or those lines go to co2 generators, (big black containers), & the other line goes to an internal filter as a diffuser.

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