DIY CO2

[wendyv]

Hi everyone, I have decided to start up my DIY CO2 system and the instructions I have say to mix 2 cups of boiled water with 2 cups of cane sugar; let cool, then mix 1/4 teaspoon of yeast with some tepid water and a little sugar and add that. Now the picture that came with the article shows the pop bottle 2/3rds full, to the line on the pop bottle. So I am confused as they say to only add 2 cups; are they forgetting to say to later fill to the line on the bottle? Does it matter how much water is put into the bottle; will it work the same?
Thanks for anyone clearing this up for me.
Wendy

[Wasserpest]

You should fill up the bottle until the line where it starts to narrow. Leaving it half empty/full will make you have to redo it more often, and it will take longer until it really starts to push CO2 into the tank, because all the air volume above needs to be displaced first.

[cich]

Also, recipes aren't THAT important. I use approx 2 cups white sugar, a pinch of yeast, and that's it. Non-boiled water seems to work fine too. Boiling it probably works best, but I'm saying, if you're like me and just couldn't be bothered, take the easy way, hehehe.

--cich

[malkore]

boiling just ensures the sugar is totally dissolved, and that there's no foreign yeasts/molds in the water that might cause problems.
I tend to use 1.5 cups of sugar for a 2liter setup. If you've got 1 gallon jugs, you can use 2 cups.

[wendyv]

Thanks everyone I didn't realize I had any answers. Set it up yesterday with 2 cups cane sugar and the water plus 1/2 teas. yeast. Looks like condensation on the tops of the bottles (I made two 2 litre bottles with a smaller bottle at the end of them) and condensation in the smaller bottle. I just put the airline to the end of the intake of my filter; so really can't see any bubbles going into it. Is this an okay way to get the CO2 into the tank?
Also if no one minds another question; I have to Penquin 300 bio-wheel filters one on either end of the tank, which from what I presume switches the water at 600 gph for the two. There is quite a lot of movement on the top of the water and you can see the oxygen (presume?) bubbles from the out takes going into the water. Do you think that this is too much oxygen going into the tank? I want my 9 not full grown Orandas to be safe but still want beautiful plants. So want the oxygen and CO2 to be just right.
Thanks for any replies.
Wendy

[Wasserpest]

The bio-wheels and surface agitation will ventilate out all CO2 that you are trying to add. A soda bottle on a 75 gal tank will not have a big impact anyway. Good news is, there are still a lot of plants that grow without added CO2!

[wendyv]

Thanks for replying. Well I am getting frustrated I am afraid:-(. I put in these two Envirolites which are full spectrum, look like compact flourescents for the house; 95 watts each; one on each end of the tank plus have another 2 - 3ft. flourescents in front of those - 30 watts each; thought these lights would work really well as they are for growing indoor plants and don't get hot. Anyway seems now the green algae is growing more on the plants. I add liquid fertilizer; Leaf Zone by Aquarium Pharm. weekly, have some laterite in the gravel along with added iron tabs from Aquarium Pharm. too. My ph is around 7.4-7.6 and hardness is 6ppm. as using rainwater for water changes. On another forum someone told me I am trying to do two different things at one, have orandas which need lots of o2 and have plants that need lots of co2; so from what I am figuring, I will probably have to decide one or the other:-(. I love my fish, so guess that is what I have to keep alive more. I do love plants too though and these are looking stunted and have green algae all over the leaves; except for the cobomba and that hasn't any; nice green growth on top.
Just out of curiosity I have read all over the forums that these DIY co2 two bottles systems work; maybe not as well on a larger tank but do work. I have a magnum cannister sitting around that I could change over one Penquin biowheel to that; that way there is still lots of filtration for the fish but less agitation to the surface of the water.
What to do, what to do.........
Anyone with pointers, I would sure appreciate it.
Thanks
Wendy

[Wasserpest]

Plants produce a lot of O2 under the right conditions. For example, every day around 2 pm my tank starts to fill up with tiny oxygen bubbles. I guess this is when oxygen saturation is reached.

CO2 and O2 are not mutually exclusive. I bet if you have two identical planted tanks, one with CO2 injection, and one without, you will find the higher O2 levels in the tank with the CO2 supplementation.

The other guy in the other forum was kinda right though, if you have an overstocked, lightly planted tank, O2 levels might go down, and especially at night, when plants don't photosynthesize, reach critical levels. Some people advise to either turn off CO2 injection (with high pressure systems) or increase surface agitation, by means of additional power heads or even an airstone.

But as I said, the biowheels will reduce the CO2 to the same low level of the surrounding air, and you don't have to bother with CO2 at all. It simply has no effect. Of course the DIY method works, but it is not magic. On a smaller tank, without surface agitation, it would be effective.

Don't limit yourself by assuming that without CO2 you can't grow plants. There are plenty of them that will grow, and a nicely planted tank is possible without CO2 addition. It's when you want high light, high fertilizer dosing, maximum growth... then it becomes required.

[digger]

CO2 and O2 do not displace each other when dissolved in water. If you have healthy plants from adding CO2 your plants will make a lot of O2 for your fish.

You have 250 watts over 75 gallons. That's a lot of light. If you want to avoid algea with this much light you are going to have to get serious and start testing your co2, nitrate, and phosphate levels. You have to keep these elements (light, co2, nutrients) in balance to avoid algea.

I think your measurement of hardness is wrong. Do you mean degrees KH (dKH) instead of ppm? 6 ppm is very soft water. Did you see a ph change after adding the co2? If 7.4 is your ph after adding the co2 and your KH is 6 dKH you have 7.2 ppm CO2. About half of what you need.

Here is the co2 calculator:
http://www.csd.net/~cgadd/aqua/art_plant_co2chart.htm