DIY CO2 Setup

[Barmy]

Hey guys,

I'm looking for all the information I can on how to set up an effective DIY CO2 system on my 55g tank. I realize that a tank my size is probably getting to the point where DIY CO2 starts dropping off in effectiveness, but cost is the big factor here and I simply can't afford pressurized CO2 right now. Besides which, I know that DIY methods can work on tanks my size, as I have seen it done on several of the Australian fish-keeping forums I frequent. The real challenge is finding out how!

I know the basic rule is that the more lighting you have, the higher the demand for CO2 and micro/macro nutrients. The light I have for my tank is an LO T5 unit, holding two 28w bulbs. I have been advised on other forums that the efficiency of T5 lighting kind of throws out the watt per gallon rule, and that this lighting should do for all but the pickiest of plants (I'm not planning anything particularly demanding, anyway; I think Val is most likely the most demanding plant I'll have).

So, given the size of my tank and the lighting provided to it, what would be an effective DIY CO2 set up? How many bottles should I use at once?; What size bottles should I use?; What quantities should I use in my mixture? I know all about how to build the DIY system, but I don't know what specifications I should be basing my design on to adequately service my tank.

I'm sure there are people on here with the knowledge to help me do this - after all, making this hobby slightly more affordable is a challenge we all face! - so any advice would be very much appreciated.

Cheers,

Joe

[Teacherman]

Hi Joe,

I used to use (and will again soon) a 2 litre coke bottle with brewers yeast in it. Add tank (no chlorine) water to about 1/3 full, and dissolve as much sugar as you can in it. Add a tiny bit of yeast and away you go.

I had an upside-down plastic test tube (from a pH test kit) suction-capped onto the wall of the tank, and the CO2 from the yeast bottle went into there, and could diffuse in as required.

I only ever replaced about half the liquid at a time (with sugary water) when I noticed the bubble rate had slowed.

Hope this helps.

[corza]

I use the method that Teacherman suggests and it works a treat.

I use this recipe for my 40 gal:

2 cups of sugar

1/4 teaspoon of yeast

1/4 teaspoon of baking soda

Then just fill with luke warm water to the top line where the sticker is.

[Barmy]

How much light were you guys running on your tanks? Since more light = greater CO2 requirement, if my light is stronger than what you guys were running then I might have to play with the amounts a bit.

[EddieSalita]

Hey Joe (lovin that )

Can we have the dimensions of your tank? Tank depth is a big factor in lighting. Personally I think 2 28w T5's is nowhere near enough for a planted tank. Unless you are growing only anubias and swords who are happy with low light. Fluros dont 'throw out' the rules so much. 200 watts of T5's wont be much more light than a 200w halide. I have a 40g tank with 4 54w T5's on it. I dont grow particularly advanced plants. But things like HC which like plenty of light are quite happy in there. I could confidently say they would grow even better under 6 globes. I dont think they would be at all happy with a quarter of the light they have now.

I use a similar recipe to the one mentioned and the co2 output is fine. If my tank was any bigger I might consider 2 bottles is all. I think the real advantage of pressurized co2 is the ability to regulate the amount, and the fact that a fill will last several months or more. This recipe mentioned should easily last a week if not 2. Output can also be increased by increasing amount of yeast. Consider how you will disperse the co2. Most use the glass diffusers, ladders or reactors. I plumb mine to the power filter and i Get and ultra fine bubble mist that spends more time underwater than a simple airstone. I have been having no difficulty maintaining 20-25ppm co2 so far.

Anyway, My opinion is that light is extremely important. Not just amount, but spectrum also. Globes also get old and lose their spectrum over time. But there are many low light plants that you can choose from that will do ok in the light you have. They may not grow quickly. But they will survive and maybe grow ok.

I also dont think less light equals lees co2 required. To an extent you are right. But its the co2 concentration you are after. The extra light will just enable the plants to respire at a greater rate. They still need the co2 concentration, they just wont use as much co2. if you have 10ppm co2 with 48w of light you wont get nearly the results of 25ppm co2. So you are right in that less co2 is being used, so less needs to be replaced, but you need a certain amount of gas to get and keep the concentration up regardless.

Alot of your question depends on what type of plants you want to keep. Some dont have big light/nutrient demands. Others do. I would reccomend that if the budget allows, going for another 2 t5's. You will get much better results

Jason

[Barmy]

My light fitting has room for three bulbs, but one currently holds a nighttime bulb. If you think I need more light, I can exchange it for a daytime bulb.

With regards to the watt per gallon rule, I was under the impression it was created with T8s in mind. Given T5s are brighter and more efficient, 1 watt of T5 is better than 1 watt of T8, so the rule is thrown out of whack a bit. I might be wrong; It's just what I've heard.

My tank is 4 feet long, as is my light fixture. The tank is 18 inches deep - a standard 55 gallon.

When selecting plants I want to avoid the particularly needy ones. As mentioned in my first post, some sort of vallisneria is probably going to be the most demanding plant I'll keep.

If there's anything else you need to know, just ask.

[Teacherman]

My tank is 120 Litres, and nearly 2 foot deep. Lit by 28 24W compact fluoros, one white 10000K and a blue one that I'l be changing as soon as I can find a red/white tube to fit.

I'm hoping this will be quite sufficient for my amazon sword (radicans, I think) crypts, hygophila, anubius and java fern. The Co2 should get them going.

I have a river sand substrate over laterite, and have usd fertiliser tablets (seachem flora I think).

[EddieSalita]

I imagine it will be more than ample for those species teacherman. Are they just normal comact fluros or are they 'daylight' ones? IME when you use just normal room globes they are too rich in the green spectrum and can cause algae problems sometimes. If you have plenty of fast growing plants, you may outcompete the algae. You should see some big growth when you toss in the co2 as well. Be interesting to see how they go. Plenty of light though. Any room left under the hood for a hatch

See how you go Joe. For val and anubias, java fern and some swords and stuff like that you will probably do ok I reckon. T5's do put out more lumens per watt than T8"s generally. Were not talking a massive amount here though. 50 watts of T5 might me about 5000 lumens, and 50watts of T8 might be about 3500 lumens.... depending on globe type. These are off the top numbers. 18" is cool. I just wanted to make sure you weren't talking 2' or 2.5 deep as that would make a fair difference. If you find you dont get good growth, just whack in the extra light!

Jason

[Barmy]

My tank is 120 Litres, and nearly 2 foot deep. Lit by 28 24W compact fluoros, one white 10000K and a blue one that I'l be changing as soon as I can find a red/white tube to fit.

28 24w fluros? I assume you meant that the fluros were 28" in length, otherwise that would be crazy.

So you reckon just stick with the two globes and see how I go? Alright, I'll go with that.

[Teacherman]

Well picked up: 2x 24w fluoros!

[Barmy]

Alright, so I decided to try this on my 15g tank instead of my 55g. A smaller, empty tank should be easier, right? But I'm having problems.

First of all, it's barely making any CO2. I'm getting maybe (maybe) one bubble every six minutes. My mixture was 2 cups sugar, 1/2tsp yeast, and filled to above the Coke sticker with lukewarm water. I can see the CO2 in the tubing in the tank, slowly pushing the water down and out of the tube, but it is going agonizingly slowly. When a bubble finally does get released, the water rushes back up into the tubing until it hits the next CO2 bubble, then the slow process starts all over again.

My second problem is aiming the CO2 into my filter intake. I'm using a simple internal canister, and I've got the airline secured underneath it via a rubber band. But the pipe is pointing at the substrate rather than up into the intake. Plus, the rubber band doesn't seem like the most stable solution long-term.

Anyone have any ideas? The first problem is obvious the most pressing.

[Barmy]

And the first problem is solved with better placement of the tubing.

But the second problem has now become more concerning. Bubbles from the tube aren't being sucked into the intake of my filter, they're just bouncing off the side and floating straight up to the surface. It looks like the little slits in the filter are too small for the bubbles to fit through. So, as far as I can tell, I wont be able to get the CO2 through the filter without drilling a small hole in it for the pipe to go through, and I'm wary of doing this in case I crack the plastic.

Any suggestions? I could hook up an airstone for diffusal and see how that goes. Maybe it'll make the bubbles small enough for my filter?

[Teacherman]

I have used a plastic ph test kit test tube, inverted. So I have a permanent big bubble of CO2. It's not near the filter at all. If I take the airhose from the coke bottle out, the test tube empties over a couple of days- I assume by dissolvbing into the water.

My point is that the bubble doesn't leave the water straight away, and dissolves into the water.

Hope this helps.

[Barmy]

That sounds easier.

I take it you put the test tube underwater before inverting it, so that there's no bubble of air trapped in there?

[Teacherman]

Yep- underwater, and inverted to start with. Shake the bottle, and it yeilds extra CO2, which gets it started pretty quick. Dont squeeze the bottle though, or you get a bottle full of tank water! I've been meaning to put a one-way valve in the air line but haven't got around to it.

[EddieSalita]

It seems to me there is something wrong with your yeast or you are using water that is too warm. You should be getting much more gas than that with the recipe. Dissolve the sugar in hot water, but make sure the water is room temp or just above before you add the yeast. Some yeasts really dont like it too hot. My batch seems to just die if the water is much over 30-35 degrees when i add it.

[Barmy]

Yeah, the CO2 started coming out regularly and consistently given time and better placement of the airline tubing in the tank.

I took your idea teacherman, now I've got the airline pointing up into an inverted tube as well. It didn't take long for the tube to completely fill with CO2, and now I get at least one "overflow" bubble rising up from the bottom of the tube every minute or so, usually its more than one per minute. I take it the same thing happens in your setup?

[Teacherman]

Yep, that's how mine works. Primitive, but it seems to work!

[Happy]

I may have incorrectly read what you wrote but...

If you have one bubble every minute or so and water entering the airline after the bubble has escaped you have a leak somewhere...there should be more than enough pressure to keep the airline full of co2.

I'd suggest checking your seals and if you haven't already- silicone in the airline to the bottle cap.

[Barmy]

Hey guys,

It looks like my mixture is starting to run out of steam, as the time between "overflow" bubbles is getting further and further apart. What is the best way to get it going again? Should I re-do the whole mixture, or just add a bit more sugar and yeast to what I've already got going?

[Teacherman]

tip half out, add more cooled down sugar/water mix. Don't forget the chlorine neutraliser if you use tap water. You don't need to add more yeast- they're already in your "brew"