Consistent 2-3 bps with "pressurized" DIY CO2

[UnusualSuspect]

I mentioned this in another thread recently, thought it might be of interest.

I decided awhile back to add DIY CO2 to my 29 gal tank and quit using Excel. (I already had pressurized CO2 on my 90 gal.)

I built a 2-bottle rig with a gas separator bottle and diffused the gas thru limewood, letting the bubbles get sucked into the intake strainer of a Fluval 205.

The result was horribly inconsistent. The next morning, my drop checker was bright yellow! A day later, it was bluish-green, and the day after that it was solid blue.

So I sez to myself ... self, we need a way to even out the gas delivery here. I had some pieces-parts on hand from when I first started using pressurized CO2 on the big tank, so I rummaged around. I found an old needle valve, bubble counter and reactor. I picked up a handful of cheapo check valves at the LFS and got to work. The resulting setup is shown here:

This setup gives me a pretty consistent 2-3 bps through the week. I change out one CO2 generator bottle per week. My drop checker stays green all week. (I do give the bottles a swirl or two during the week and tweak the needle valve a little to keep it in the 2-3bps range.)

A consequence of restricting the gas flow with a needle valve is that you build up pressure on the generation side. I worried at first about an explosion, but after playing around with my yeast recipe, I seem to have reached a "happy place". It's been running about 6 weeks now, no explosions.

Part of achieving success here might lie in the size of the gas separator bottle. You want it big enough to hold plenty of gas, but small enough to maintain/deliver good pressure to the needle valve. I started with a 12oz soda bottle, but have switched to a 20oz bottle.

Go to the grocery store and fondle some of the 2-liter bottles of soda. Squeeze them, you'll find they're hard as a rock. Now (presuming you haven't been arrested for fondling soda bottles) go home and squeeze your CO2 generator bottles and your gas separator. How do they compare? They might be fine or you might want to bleed some pressure off the system and re-think your yeast recipe.

DISCLAIMER:
If you decide to try this, remember to keep a close eye on it until you're comfortable with the setup - your mileage may vary. If it explodes and splatters sugar-water, yeast and ethanol all over your shiny new plasma TV, well ... I hate to say I told you so.

You could rig up a pressure relief system. I've seen descriptions on the net for various DIY pop-off pressure relief thingies. Rex Grigg sells a low pressure regulator that I think could work in this application. I'd put it between the gas separator bottle and the needle valve, so it can't get clogged by stray yeast-goo.

There's nothing special about my yeast recipe. Two cups sugar into a clean bottle, add boiling water to just below the curve. Shake, let cool to about 100F. Activate 3/4 tsp baker's yeast, add to the bottle. Mix and hook it up to the system. Good pressure in the bottle in about 2 or 3 hours, lasts me 2 weeks.

The check valves on the generator bottles allow me to remove a bottle without de-pressurizing the system.

In this system, leaks are a killer. I built my soda bottle caps using pieces of the Clippard tubing that Rex sells - it's a very snug fit in a 3/16" hole, no leaks.

Click here to see the needle valve I'm using.

Click here to see the reactor I'm using.

JM2¢
Mike

[Rex Grigg]

Damn for $40 (adding in shipping) you could have gotten a much better needle valve.

Or you could have gotten parts and split your pressurized CO2.

[Orlando]

Originally Posted by UnusualSuspect

I mentioned this in another thread recently, thought it might be of interest.

I decided awhile back to add DIY CO2 to my 29 gal tank and quit using Excel. (I already had pressurized CO2 on my 90 gal.)

I built a 2-bottle rig with a gas separator bottle and diffused the gas thru limewood, letting the bubbles get sucked into the intake strainer of a Fluval 205.

The result was horribly inconsistent. The next morning, my drop checker was bright yellow! A day later, it was bluish-green, and the day after that it was solid blue.

So I sez to myself ... self, we need a way to even out the gas delivery here. I had some pieces-parts on hand from when I first started using pressurized CO2 on the big tank, so I rummaged around. I found an old needle valve, bubble counter and reactor. I picked up a handful of cheapo check valves at the LFS and got to work. The resulting setup is shown here:

This setup gives me a pretty consistent 2-3 bps through the week. I change out one CO2 generator bottle per week. My drop checker stays green all week. (I do give the bottles a swirl or two during the week and tweak the needle valve a little to keep it in the 2-3bps range.)

A consequence of restricting the gas flow with a needle valve is that you build up pressure on the generation side. I worried at first about an explosion, but after playing around with my yeast recipe, I seem to have reached a "happy place". It's been running about 6 weeks now, no explosions.

Part of achieving success here might lie in the size of the gas separator bottle. You want it big enough to hold plenty of gas, but small enough to maintain/deliver good pressure to the needle valve. I started with a 12oz soda bottle, but have switched to a 20oz bottle.

Go to the grocery store and fondle some of the 2-liter bottles of soda. Squeeze them, you'll find they're hard as a rock. Now (presuming you haven't been arrested for fondling soda bottles) go home and squeeze your CO2 generator bottles and your gas separator. How do they compare? They might be fine or you might want to bleed some pressure off the system and re-think your yeast recipe.

DISCLAIMER:
If you decide to try this, remember to keep a close eye on it until you're comfortable with the setup - your mileage may vary. If it explodes and splatters sugar-water, yeast and ethanol all over your shiny new plasma TV, well ... I hate to say I told you so.

You could rig up a pressure relief system. I've seen descriptions on the net for various DIY pop-off pressure relief thingies. Rex Grigg sells a low pressure regulator that I think could work in this application. I'd put it between the gas separator bottle and the needle valve, so it can't get clogged by stray yeast-goo.

There's nothing special about my yeast recipe. Two cups sugar into a clean bottle, add boiling water to just below the curve. Shake, let cool to about 100F. Activate 3/4 tsp baker's yeast, add to the bottle. Mix and hook it up to the system. Good pressure in the bottle in about 2 or 3 hours, lasts me 2 weeks.

The check valves on the generator bottles allow me to remove a bottle without de-pressurizing the system.

In this system, leaks are a killer. I built my soda bottle caps using pieces of the Clippard tubing that Rex sells - it's a very snug fit in a 3/16" hole, no leaks.

Click here to see the needle valve I'm using.

Click here to see the reactor I'm using.

JM2¢
Mike

Good job! DIY co2 is livin! Thanks for sharing Mike.

[UnusualSuspect]

Originally Posted by Rex Grigg

Damn for $40 (adding in shipping) you could have gotten a much better needle valve.

Or you could have gotten parts and split your pressurized CO2.

Built from parts on hand. I had these things sitting in a junk box, left over from a year ago from my first foray into CO2, when I was truly a lost and desperate aquarist.

When I started with CO2, I was pretty much buying whatever parts the LFS could order from their catalog. They didn't have any other customers doing CO2 at the time, so they were learning along with me. (FWIW, I recommended your regulators to them, gave them the literature that you sent with my Rex-ulator.)

Yes, I considered splitting the pressurized CO2, but (a) it's a long-ish run between the two tanks, and (b) this gave me a project to work on for awhile.

I'll probably replace this tank soon - I'm thinking a 36 bow - and may go pressurized at that time. If so, I'll be in touch for parts.

Mike

[swylie]

Originally Posted by UnusualSuspect

So I sez to myself ... self, we need a way to even out the gas delivery here. I had some pieces-parts on hand from when I first started using pressurized CO2 on the big tank, so I rummaged around. I found an old needle valve, bubble counter and reactor. I picked up a handful of cheapo check valves at the LFS and got to work.

I once thought about doing something like this but it occurred to me that it could explode so I never went any farther. As you've demonstrated, if you do it right it won't explode. I guess it's a balance between the amount of yeast you add and the bubble rate you're using. It occurs to me that there might be some negative feedback built into the system though, which is a good thing, and would reduce the risk of explosion. When the pressure builds up in the bottle the water is more acidic from more dissolved CO2. The acidic water might slow down the yeast and diminish the additional production of CO2. Since DIY CO2 can explode this negative feedback can't be enough to completely stop the yeast, but it might slow it down a bunch. I don't know. I suppose I could answer my question by sealing off a DIY CO2 bottle with a pressure gauge attached and monitoring the pressure over time. If the pressure increase is close to linear then the added pressure and acidity doesn't slow the yeast much. If it's a curve, then there's significant negative feedback.

I have a feeling that your setup won't work for many people because it requires more monitoring and a more delicate balance than regular DIY CO2. That said, I think it's awesome that you've got this working for you. Oh, one more thing. Keep in mind that your needle valve is a flow regulator, not a pressure regulator, and that the flow through it will vary somewhat with the pressure across it. I guess this is another built in safety feature, since your valve will flow more CO2 at higher pressures.

Anyway, congrats on showing that it can work.

[UnusualSuspect]

Originally Posted by swylie

Oh, one more thing. Keep in mind that your needle valve is a flow regulator, not a pressure regulator, and that the flow through it will vary somewhat with the pressure across it.

Yep, gotta tweak the valve a little thru the week as pressure in the bottles decreases. Not much, though.

When I replaced one of my generator bottles this morning, the whole system de-pressurized as a result of a cheapo check valve not working properly. There's a drawback to doing things on the cheap.

Thanks,
Mike

[jaidexl]

Glad to see I was understanding you properly in the other thread, nice diagram.

Easy solution to fear of explosion> place the bottles in a covered tupperware container with holes drilled for tubing. Or inside a large plush animal so you're tank would be fed CO2 from a huge fuzzy teddybear with a needle valve sticking out of his head.

[swylie]

Originally Posted by jaidexl

Glad to see I was understanding you properly in the other thread, nice diagram.

Easy solution to fear of explosion> place the bottles in a covered tupperware container with holes drilled for tubing. Or inside a large plush animal so you're tank would be fed CO2 from a huge fuzzy teddybear with a needle valve sticking out of his head.

Your ideas are intriguing to me and I wish to subscribe to your newsletter.

[tropicalfish]

Originally Posted by jaidexl

Glad to see I was understanding you properly in the other thread, nice diagram.

Easy solution to fear of explosion> place the bottles in a covered tupperware container with holes drilled for tubing. Or inside a large plush animal so you're tank would be fed CO2 from a huge fuzzy teddybear with a needle valve sticking out of his head.

"Mommy! My teddy bear is wet and stinky!"
"Go ask your dad...

[jaidexl]

Bwahahahaaa!


There's a huge stuffed monkey sitting here that my fiance wants to get rid of, I think I might blow that sucker up with a yeast bomb.

[UnusualSuspect]

Update: I have not added any stuffed monkeys to the setup.

Two weeks ago, the tank magically morphed from a 29gal with 65 watts to a 36 bow with 130 watts. I used Black Fluorite. Jeez I love this tank!

Anyway, about the CO2 - I switched the gas separator/gas storage bottle from a 20oz to a 1 liter, and it seems to be about the perfect size. For my yeast recipe, I cut back to 1/2 tsp yeast.

This thing has gotten really reliable, I haven't had to tweak the needle valve in about three weeks now, and I'm not swirling the bottles, either. Swap out a generator bottle each week at water change time, and it just stays pegged in the 2-3bps range all week. My drop checker stays solid green at all times.

I (again) considered splitting the pressurized CO2 from my 90 gal, but this thing has settled into a groove and I don't really see the need.

Hard to believe, but DIY CO2 is supplying all the gas I need in a heavily-planted hi-tech 36 bow with 3.6 wpg.

Regards,
Mike