# how to limit CO2 with the DIY system



## titan97 (Feb 14, 2005)

I haven't the $$ to invest in a pressurized CO2 system. Maybe Santa will be nice to me this X-mas. Anyway, I'm therefore using a DIY system compromised of 2x2L bottles connected to the intake of my Eheim. I went from 10ppm with my simple bell diffuser to way over 60ppm with the Eheim. Of course, now my fish hover near the surface of the tank. I have hooked up an air stone to a timer that turns on when the lights turn off at night, blowing off a large portion of the CO2. The air pump runs only for 2 hours, allowing the CO2 to build up for the remainder of the night and be near optimal conditions in the morning. My question is this:
What can I do to reduce the CO2 during the day, but still to a good amount for the plants? I thought of moving the spray bar output of the Eheim closer to the surface and/or pointing it in a direction to get more agitation? Or perhaps install a Tee in the airline for the air stone and use a valve to bleed off some of the air, reducing the amount that gets used to agitate the tank?
In the near future (2 to 3 weeks), I'll be finished with my DIY ODNO lighting system and go from 1.8WPG to over 4WPG. I hope this will increase the rate of photosynthesis in the plants, and use them to generate more O2 for the fish. Assuming that will help, what do I do until then?

Anyone, anyone? Bueller, Bueller?  

-Dustin


----------



## czado (May 26, 2005)

How about using one 2L bottle? If you want the better stability that comes from multiple bottles, use two 1L bottles with appropriate mixes. You could also do some experiments with the mix, or run the air pump during the photoperiod.


----------



## Simpte 27 (Jul 16, 2004)

I would love to know what mixture you're using to get 60ppm with diy CO2. I use 2-2litres also and have a hard enough time keeping 20ppm let alone 30.


----------



## dinajel (Jun 7, 2005)

Try using less yeast. Less yeast gives a slower "brewing", so you will get fewer bubbles per second, but your DIY CO2 will last longer. This is in my experience. Others may disagree, but it might be worth a try.


----------



## PascalvdN (Jul 22, 2005)

I'm afraid that these DIY bottles cannot be controlled properly in the setup you are using at the moment. What I use for smaller tanks where I also make use of bio-co2 is the inverted cup method. This way you can accuratly control the amount of CO2 in the tank.

Pascal


----------



## titan97 (Feb 14, 2005)

My DIY mixture is ~2 cups of cheap, granulated sugar and 1/2 to 3/4 tsp of yeast. I replace the 2L bottles once every 3 weeks. And I rotate the bottles so that I replace one, then the other the next week, then I have a week off, repeat. Going into the Eheim I usually see about 1 to 3 bubbles per seconds, and I have little-to-no other agitation in the tank. I like to keep my KH high at about 12 to prevent huge pH swings that I would get when the CO2 gets really going. In the morning I see a pH of about 6.8, and it get down to about 6.6-6.7 towards the evening. Once the air stone kicks on, the pH jumps to about 7.0 to 7.1, maybe higher but I am usually asleep by this time. I should also mention that I just moved to Yuma, AZ, and my house temps are in the mid-80s. I'm sure the higher temps here versus in San Diego are causing the yeast to grow faster.
I'm due to change one of the bottles this weekend. I'll try to reduce the amount of yeast in the bottle and see what I get there. I guess anything that reduces my bubbles per minute will reduce my CO2 concentration.
I'd think about using the air stone during the photoperiod, but it really knocks the concentration way down.
Well, I think I have some ideas. At least enough to get me started. Thanks amigos.

-Dustin


----------

