How many 2L's to use?

[evercl92]

Basically I'm looking for imput on how many 2L bottles to connect to provide sufficient CO2 for my tank.

tank specs:
125gal - 48in x 24in x 24in, 390wt CF lighting, using Greg Watson ferts, very heavily planted (pictures here)

I currently have 2 2L's setup up, running well, but I'm assuming I could probably use some more. I would like to stick to using the single glass diffuser that I have, (though I don't think it would have an issue handling 8 bottles), and using T-pieces to connect the system. TIA

 

[875mill]

I would start with a min of 6 ,but you will prolly need more. Would prolly be better in the long run to go pressurized to maintain a constant c02 level.

 

[rkilling1]

I think you would be best going with a pressurized setup also, but going the diy way imo i would setup two power reactors with 2 2L bottles (4 total). i am currently running 1 2L bottle on my 28 gal tank with a power reactor (plantbrain type) and getting 30 PPM CO2. so i think you should be able to get around 25 ppm CO2 with only 4 2L bottles that way.

 

[fish_4_all]

If you need to stay with DIY CO2, 6-8 bottles set up with 2 cups of sugar each and the best yeast you can buy, probably wine yeast. One DIY reactor for every 2 bottles. Feed the CO2 into different parts of the tanks if possible. Make sure to have good circulation so if one isn't working really well then the other two could compensate.

Personally it's hard enough to get high enough CO2 using two 2 liter bottles on a 10 gallon tank and maintaining it so I don't have BBA outbreaks. Pressurized would definatly be the way to go and would save you a ton of money in the long, well not so long run.

 

[Lonewolfblue]

For 125G, I would say more than 8, lol. Had to vote 8, as that was the highest. More like 10.

 

[mr funktastic]

pressurized will be cheaper lol. 8 i think would be good but thats assuming u have a wicked diffuser. a regualtor is about 100 bucks and a co2 bottle is about 80 for a 5-10 pound bottle. so lets say 200 after reactor bottle and line and all that stuff. then only lik 10 bucks to fill it every 3-4 months. u will spend 10 everymonth in sugar and yeast atleast and be lucky to hit 30 ppm of co2. it just becomes impracticle after about 55 gal.

 

[Burks]

Once you get past maybe 55g the only way to go is pressurized. In the long (in this case, probably short) run of things it will save you money, time, and effort. With luck you can get 3 weeks out of a bottle, that's a lot of money each month on yeast and sugar.

Spend the extra money on a pressurized system and you'll be very, very happy. Personally I won't use yeast CO2 on my 40g breeder. Easier to use a pressurized system and be done with it. Spend my time worrying whether or not that crypt looks better here or there rather than if my CO2 will last another day.

If I had to choose, 10 bottles would be ok.

 

[Lonewolfblue]

For a 10lb, it will cost about 20.00 per year to fill. The bottle will last a year. My 5lb on my 75G lasted 6 months.

 

[evercl92]

I'm hopefully getting some equipment (CO2 tank, 2.5lbs I think, regulator, and reactor) for free here soon. I just need to work out the details. Sounds like I need a lot of bottles to have decent CO2 levels.

 

[7Enigma]

It all comes down to your diffusion method. The efficiency that you can get the CO2 into and stay in the water will completely determine the amount of bottles you need. I would say at least 1 bottle per 20 gallons, and I'd stagger them at least 50/50 (so 1/2 you change one week, 1/2 the next).

I'd use cheap bakers yeast and reuse it, with only replacing the sugar. Most bakers yeast will settle at the bottom when it peters out, and you can simply drain off the top, and add new sugar water.

This is quite an ambitious goal, but I think with the right method of deployment you can *possibly* get adequate levels (20-25ppm).

Cheap plug for my thread currently discussing diffusion methods...................

 

[maxwell1295]

For 125g, you'd probably need a least (4) 1 gallon containers. For a tank that size, it would be much cheaper to run a pressurized system. The amount of sugar you'd have to buy would cost you more than filling a 20lb CO2 bottle a couple of times a year.

 

[evercl92]

I have the CO2 going through the diffuser, which then directly flows up into the output of my powerhead. That then blows it most of the way across the tank. Bubbles are pretty close to gone before hitting the water's surface.

Pictured is the diffuser that I have:

 

[maxwell1295]

I have those diffusers. They are fine as long as the disk is intact and keeps a tight seal with the glass. What normally happens is that they somehow lose their seal and you get these huge bubbles that are pretty much useless. I bought a bunch of these cheap on eBay and have 1 or 2 left. I figure I can get another 6 months out of them before I need to start looking into something better. Now that I have a canister running on my main tank, I may end upp going with an inline reactor like the one designed by Rex Grigg.

 

[Purrbox]

I would guess that you would need either 10-12 2 Liter bottles or 5-6 1 Gallon bottles to have a chance at getting high enough CO2 levels. Might be able to reduce it slightly if you improve your diffusion method.

 

[evercl92]

Can I assume my CO2 levels using Chuck's Calculator with pH and kh values? If you aren't using that method to determine CO2 ppm, then what do you use?

 

[Purrbox]

You can use Chuck's Calculator to calculate your CO2 levels if you verify that you water doesn't contain any buffers/acids that throw off the pH/KH relationship.

1. Collect a glass of source water used for water changes
2. Let sit 24 hours or aerate for an hour (This will gas off any extra CO2 injected into the water by water treatments)
3. Test for pH and KH
4. Calculate CO2 levels

You results should be approximately 3ppm, which is the ambient CO2 level. If not, you will need to use an alternate method to calculate your CO2 levels.

 

[Burks]

Problem with the type of diffuser you posted is they can clog due to using yeast. You'll have to keep up with that as you'll be pushing a lot of bottles through a few diffusers.