Requesting reply from Aquatic-Store, et al.

[CJhearsu]

I noticed Aquatic-Store's post concerning Eheims as a good CO2 reactor, and hope I can get an answer to my question. I just bought an Eheim 2213 Classic and set up a DIY yeast-based CO2 generator. I fed the CO2 airline to the basket on the Eheim's intake tube. My generator is producing LOTS of CO2 (1 bubble every two seconds, but that may slow down, of course). What is happening is that the CO2 gas is being trapped in the filter media that came with the Eheim, then every few minutes, the CO2 builds up enough that the canister has to release it, causing a rush of CO2 bubbles into the output tube/spray bar. I'm not sure that any of the CO2 is actually being dissolved, and I'm also concerned that this all-at-once release of the gas is going to damage the impeller. It certainly causes the Eheim to produce some noise.

Any and all input will be greatly appreciated, as this is my first aquarium in many years, and I'm trying to do this right the first time (but on a budget!)

Thank you,

CJ

[RTR]

Many folks do use Eheims as reactors, as they are engineered to avoid air-locking (many canisters are not). but noise is associated with the impeller breaking up the bubbles, and some bubbles being pumped into the tank is common.

The trapping of the CO2 by the media is not uncommon either. I object to it as it could alter the flow through the filter, especially from DIY CO2, as some of the trapped gas is likely air - which will not dissolve as CO2 does.

I do not use my Eheims this way, I don't like the noise. I'd use a reactor, or at least the little "ladder" device from the Hagen CO2 generator units (commercial version of DIY).

[CJhearsu]

Many thanks for replying, RTR. What exactly does air-locking mean? I removed my CO2 generator last night because after a few dozen "burping" sessions, enough air built up in the output line from the Eheim (or within the cannister, or both) to interrupt the water flow. Is that what you mean by air-locking? Also, since the Eheim theoretically should be an airtight closed system, how does any other air besides the CO2 injected at the return tube basket get into the cannister? Are you speaking of other gases produced by the yeast along with the CO2, or gases (oxygen, hydrogen, nitrogen, etc.) that are released from the water within the cannister as part of the filtering process? Is my Eheim working properly, or could I have made a critical error in setting it up? It seems to work great without the addition of the CO2.

I do not mind the occasional noise from the Eheim, and view the gush of bubbles as a good thing in one way: I have a 30-gallon hex and the spray bar is too long to mount horizontally on any of the equidistant sides, so I get zero surface disturbance on the water since the spray bar is totally mounted under the waterline in vertical position. At least the bubbles disturb the water surface occasionally to mix in a little oxygen, although the number of plants I plan on having will probably suffice as oxygen producers anyway.

I thought I'd try reattaching the generator today to see if the initial CO2 production had slowed any from the extreme 30 bubbles a minute. Perhaps at a slower production rate (say 4 to 8 bubbles a minute), the CO2 would have more time to dissolve into the water while trapped in the filter media, then the Eheim would burp a lot less often.

Any replys will be appreciated.

Thanks,

CJ

[beviking]

Airlocking, in the text RTR was refering to, is any air that would get into certain canister filters would not be ablt to get out. The filter simply was/is not designed to expell air. The air would interupt the flow of water - generally b/c the impellar is at the top which is where the air ends up and an impellar spinning in air does not pump any water.
By definition, air lock would be air causing the flow to stop, so you do have an air lock, just a little different than what RTR was talking about.

Once the carbon (C) dissolves out of CO2...you're left with...O2. No matter how long it stays in contact with the water, the air will not mix completely, you'll always have bubbles. Sounds like your filter is set up correctly. Fermenting yeast does stink though and leads one to believe there MUST be some other gasses produced!:D

[CJhearsu]

Thanks. I kinda thought that's what it meant. Think I'll just post a request for best suggestions on non-DIY diffusers and buy one.

CJ

[RTR]

Eheims have a small vent from the impeller chamber to the output line to avoid air-lock. So long as that is not blocked , the impeller will not air-lock. Densely packed fiberfill type media can block from gases as well.

When DIY is first set, the top of the bottle and the lines are full of plain ordinary air - that all is pushed into the filter/reactor/whatever is downstream of the fermentation vessel and lines, and underwater air will not dissolve ordinarily. CO2 will dissolve - it is quite soluble. It leaves the air behind.

[beviking]

Originally posted by RTR

The trapping of the CO2 by the media is not uncommon either. I object to it as it could alter the flow through the filter, especially from DIY CO2, as some of the trapped gas is likely air - which will not dissolve as CO2 does.

I do not use my Eheims this way, I don't like the noise. I'd use a reactor, or at least the little "ladder" device from the Hagen CO2 generator units (commercial version of DIY).

RTR, does pressurized CO2 causes less problems when using the filter as the reactor? I plan on using my XP3 as the reactor - unless it drives me nuts which sounds likely.
The Hagen "ladder", does that require a power head? It seems to me to be a passive device - CO2 enters the bottom and is allowed to gradually work its way up. I would rather go with something like that than running a power-head/reactor hook-up.

[RTR]

No, the Hagen device is for small-scale DIY setups - I don't know if it could handle much output. It is not very big - a very small upside down marble raceway for CO2 bubbles inside the tank - I think they limit size to 20 gallons.

IME, pressurized CO2 is much "cleaner" in that there is only airline tubing with air at bottle change (which is only every x number of months, not every couple of weeks), not the top of a fermentor vessel, so purges much more easily. But I still prefer a reactor myself.

[beviking]

Thanks again! I might as well make one now!:)

[125gJoe]

I'm using this one from Floridadriftwood.com

http://www.floridadriftwood.com/images/products/Power_reactor.jpg

I'm not wasting any CO2 bubbles. They are completely diffusing.