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need some CO2 tips

5K views 20 replies 6 participants last post by  fish_4_all 
#1 ·
well, I might have to bite the bullet and get some cO2 for my tank. Probably DIY CO2 because I am very frugal. I need some tips from people who have done this before.

A) How can I ensure that my bottle will not blow up?

B) How can I ensure that the yeast/sugar won't get sucked into my aquarium?

C) What is the smallest, easiest-to-hide-the-equipment way to diffuse CO2 in my tank? my tank is very small, 15 gallons ... i don't want to put any more "things" inside the tank if I can avoid it...or if i do they must be very small and easy to hide...

thanks in advance!
 
#3 ·
DIY is rather easy, the only real hard part is to get the whole thing to stay sealed with no leaks.

2, 2 liter bottles sealed with thread tape, the white tape for preventing leaks, with a catch bottle in the middle. I have a drawing somewhere but if I can't find it I will make another one today I hope.

As for a diffusor, what type of filter do you have? If you have a good HOB then you can pipe the CO2 directly into the intake and the filter will do a majority of the diffusion for you. If not, we will work on something else that is small and easy to use.
 
#6 ·
The catch bottle is just that, it is inline from the 2 liter bottles to catch any overflow you might have from the bottles. I used a small peanut butter jar, a plastic one for this when I did mine. I fed the CO2 right into the intake of my AC filters and could get levels up to 50ppm.

As for the bottles exploding, always check to make sure they are not clogged. I have seen pictures of the aftermath from DIY CO2 exploding and it was a nasty mess. That and the smell is not the most pleasant if you can imagine a straight alcohol and yeast mixture all over the room.

Check valves are also recommended by some but I could never get them to work for me.

I will have the picture when I have time and feel up to drawing one if I can't find the ones I have already. Sometimes I hate computers, can never remember where I saved something.

And don't worry about CO2 displacing oxygen, it simply doesn't happen. Fish gasp at the surface because levels get too high, not because of the lack of oxygen. Levels should stay between 30 and 50ppm. Also, make sure your KH is at least 3dKH to prevent major pH swings and stays there. CO2 will lower you pH and a low or non existant KH can cause serious trama to your fish from pH swings.

Download the following calculator to help you keep track of your CO2 levels as well as guidelines for dosing fertilizers.
http://www.csd.net/~cgadd/aqua/art_plant_aquacalc.htm
 
#8 ·
Thanks for the tips and the picture!! would I put the sugar/yeast mixture in both of the bottles on the left? And why 2 bottles, is that to produce more CO2? why is the longer airhose stem needed in the catch bottle?

also this might be a dumb question but is it OK for the bottles to be lower than the tank? I would have to hide them somewhere on the floor because the back of my tank doesn't have any background on it ... it's open so that it can get some window light. i have a hard time hiding my wires and stuff because of that, but the plants seem to like it a lot.
 
#9 ·
2 bottles serve 2 purposes. The first you pointed out, more production. The other purpose is so that you can rotate out bottles instead of making new mixes in both bottles at the same time. As you can imagine, this will allow for consistant levels and less of a drop off when replacing bottles.

The longer tube allows for anything that might get into the bottle to be out of the reach of the shorter tube. That way if you do have any overflow, I never saw any, there is very little chance of any of it fouling your tank.

As for putting it below the tank, yes you can but you will need to use check valves for sure to prevent reverse suction from ever occuring. Make sure not to skimp on the quality of the check valves either as the alcohol mixture and the CO2 are hard on them and cause the cheaper ones to fail quickly.

There is a plumbing fixture called a bulkhead that can make the whole setup much easier to use. They are spendy at $5-7 for a pair but for the ease they would create in changing bottles it would be worth it. If I ever do another DIY setup I will use them for sure.

Also, if you put quality check valves on the tubing for each bottle and on the main feed to the tank you can change out a bottle without interupting the flow of CO2 from the other bottle. It may slow it down but it shouldn't stop that way.
 
#14 ·
Thanks again for the tips ... I'm stoked, I finally got my CO2 set up this weekend and it's working!! :D I have the air tube feeding into the intake of my power filter and I hear it chopping up the bubbles every now and then. I put my yeast/sugar bottle in a fish bucket with some warm water and a heater. Now I just have to sit back and wait for my tank to turn into a beautiful jungle of green....hopefully :)
 
#15 ·
Wow this is all very complicated... Is CO2 absolutely necessary? I thought like air pumps helped with this? I know very little about plants but I would like to learn... After reading this thread I think it would be easier just to buy one of those CO2 things at my lfs... I was looking at it the other day... But if I just bought tabs where would I place them? Just right in the tank? Sorry about the stupid questions...
 
#16 ·
no those are very good questions :)

Is CO2 absolutely necessary?
I am no expert so maybe someone can correct me, but based on what I have been reading I think CO2 helps plants grow faster in high light or medium light tanks. If you have slow-growing, low-light tank then you probably wouldn't need it. Also Flourish Excel is an alternate way to give your plants carbon and you could try that with or without adding CO2.

My tank gets a ton of direct sunlight. Lots of light encourages more photosynthesis, and photosynthesis needs carbon dioxide. Some of my plants were running out of carbon dioxide and trying to get carbon from minerals in the water instead. which is called biogenic decalcification and it causes mineral deposits on the leaves which is not pretty. that is why I started adding Flourish Excel and CO2 to my tank, to get rid of the mineral deposits on my leaves. so far it is working.

I thought like air pumps helped with this?
Actually any kind of surface turbulence will cause CO2 to evaporate from the water (sort of like shaking soda)

After reading this thread I think it would be easier just to buy one of those CO2 things at my lfs...
Those can be good, then you won't have to deal with making it yourself, it is hard to make an airtight container. I actually caved in and bought a bottle with the airhose attachment so I don't have to mess with making an airtight seal. :)

if I just bought tabs where would I place them? Just right in the tank?
do you mean the Jungle Green Fizz Tabs? Those go in a container that sits outside the tank, the little container produces bubbles and it's connected to the tank by an air hose. Inside the tank is an upside-down plastic bowl where the bubbles can collect. That way the CO2 gas is always in contact with the water and it gradually dissolves.

You could mix and match actually - with one of each:
A) a way to produce CO2 (i.e., yeast/sugar bottle or fizz tabs),
B) an air tube to connect it to the tank, and
C) a way to dissolve the CO2 inside the tank (this can be the upside down bowl, a powerhead or filter to chop up the bubbles, a diffuser, or something else)
 
#17 ·
That would cover it pretty much. I will add that CO2, regardless of your light levels will help plant growth. The normal amount of CO2 in water is about 3ppm. If you do NOT inject CO2 then you need surface agitation to both replenish oxygen AND CO2. The normal range that most shoot for in heavily planted tanks is over 30ppm but under 50ppm. Above 30ppm and a steady CO2 level is the key here. Fluctuating levels can be your worst enemy and actually cause some serious algae problems including Black Brush Algae and other nasty ones that are hard to get rid of. Why it does I don't know but when I did DIY CO2 my levels would fluctuate badly, especially in the winter, and I got the worst case of BBA I had ever seen.

I love Flourish Excel, it not only helps immensely with growth but you can spot treat any algae you have to kill the algae. The company won't admit it is an algaecide but trust me, it works extremely well.

Some will say anything over 2 w/g and you need it, some say 3 w/g, I say if you can set it up, then go for it. As for effectiveness, here is MHO about that:(in order of least to most effective).
Any tab reactor
DIY
Excel
Pressurized
 
#18 ·
Lol this is all a lot of information to absorb. But I think I get the basics... I didn't realize how much went into the live plants :checkedout: It's a whole new ball game but I hope I can get better at this. Thanks so much for your reply! Yes I was talking about the jungle tabs... Lol okay I completely understand how the CO2 container functions... So is the air pump "evaporating CO2" Is kind of the same thing as the container and tablets "dissolving CO2"? I thought fish were complicated. I suppose it's pretty basic I'll just read up on it some more. I suppose my only question now is... Testing for CO2? I suppose it's another test kit I'm going to want to invest in? Thanks for your help!!! I hope my not fully understanding this isn't to painful. I know it's hurting my brain.
 
#19 ·
If you already have a pH and kH test kit then you could figure out the CO2 level based on that. (assuming you don't add any water hardeners or softeners to your water.) I read about that here - it has a calculator too:
http://www.csd.net/~cgadd/aqua/art_plant_co2chart.htm

I am a little confused about the gas exchange thing ... I thought that using an air pump with regular air causes CO2 to leave the water. but fish4all says that the surface agitations helps to replenish CO2 and I will be the first to admit he has been doing this for a lot longer than I have :) fish4all how does that work? maybe does the air pump cause the CO2 concentration in the water to match whatever is the CO2 concentration of the air? so it would add CO2 if you have no CO2 in your water and remove it if you have a lot of CO2 in your water? i am just guessing but that would make sense to me.
 
#20 ·
Ah! Okay, I don't have a test kit for kH but I've been thinking about getting one. I know that it's not absolutely necessary but if I'm getting into the live plants it will be a good idea to invest in. Thank you for the link, I put it on my favorites. I'll be waiting to see what fish4all has to say. You have been a great help! Thank you!
 
#21 ·
Ok I just want to make sure it is clear. IF you DO NOT inject CO2 then surface agitation helps replenish both CO2 and O2 if levels drop below normal levels. If you inject CO2 in any way then surface agitation is your enemy because it will gas off the CO2.

As for gas exchange, surface area is the best friend for gas exchange. A minimul amount of air is absorbed by water from an airstone even if you are pumping massive amounts of air into the water. The surface area of the water, which can be increased by 5-10 fold with surface agitiation, is where most gas exchange takes place. The amount of O2 and CO2 that wants to be in the water is determined by the water chemistry and temperature.

Is why when you inject CO2 you need to make sure that the CO2 gas is in contact with the water as long as possible before it reaches the surface. O2 is the same way. If you really want to increase the levels of O2 in your tank then you would need some sort of gas reactor for O2 just like you would for CO2.

The best example I have is in summer when the wind dies down and there are no waves on the smaller ponds. This is when some of these ponds can become stagnant and utlimately completely lose all the oxygen in the water killing most life in the water. If thw wind blows then the surface agitiation will allow for faster gas exchange and higher O2 levels. Is why as long as river flows it can not go stagnant. Fish farms will run huge fountains to agitiate the waters surface and help in CO2 absorption.

I know my explanations isn't scientific but I hope it helps.
 
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