Re: [APD] Re:CO2 Reactor Questions -- or - I'm for never blowingbubbles

["S. Hieber" <shieber at yahoo_com>]

--- Robert H <robertph3 at comcast_net> wrote:

> I can't say how well a cannister works, because I have
> never done it, but
> the point of a reactor is to hold the gas and the water
> together long enough
> so that the gas stays in contact with the water and
> becomes absorbed. If C02
> bubbles are allowed to escape, they float up to the water
> surface and
> disapate. I have pumped C02 into a powerhead and can see
> many little bubbles
> rising to the surface.

You mistake my meaning. I've been a fan of external
reactors since the first time I used one. I've used some
other methods but once I tried that I never had an interest
in doing it any other way. But some other ways are much
easier (and sometimes less costly for folks). running CO2
into a powerhead that outputs into an external reactor is a
very good way to make a small reactor with a low waterflow
work very well even for relatively large tanks.  That's how
Tom's design works. In my posted from which you quoted, I
mentioned using a powerhead to drive water and CO2 into an
external reactor. You can get 100% absorbtion that way.
With an external reactor you don't have to blow any CO2
bubbles into the aquarium where they rise to the surface
and pop into the atmosphere. But the reactor doesn't care
if the pump sending it water is a canister or powerhead or
sump ;-) . I've used all three and the reactor really
didn't perform diff with diff kinds of pumps.

But while we're on the subject of forever blowing bubbles,
I've seen CO2 lines run into powerheads that output diectly
into the aqurium. It's effective at acheiving CO2 levels
but not especially efficient; a lot of CO2 goes up to the
surface as bubbles and out of the tank. There's nothing
wrong with that method -- it's has advantages and
disadvantages: It's cheap for startup costs, especially if
you're running a powerhead anyhow and doesn't risk locking
up your canister, which some folks have complained about
the direct to canister method. Otoh, it uses loads more CO2
than, say, my favorite, an external reactor.

> >>I have a reactor from Tom Barr that works that way and
> it
> cut my CO2 use by about 4-fold compared to some other
> devices I had tried. 5 pounds of CO2 can easily last more
> than a year.<<
> 
> Scott, you also have at least two Aqua Medic reactor
> 1000s that I know of!

Believe it or not, I already knew that ;-) but it never
hurts to be reminded.

> Whether you use a homemade reactor like Tom's or
> Ghazanfar's, or a brand
> name like Aqua Medic, it basically works the same. The
> gas comes into the
> reactor chamber along with water and is forced thru bio
> type balls or some
> other material where the bubbles are broken up and
> churned around until they
> are absorbed. Any reactor will cut C02 use 4 fold
> compared to a diffusor, 

Whether 4 fold in each person's case or not -- hmmm, lots
of factors are at play. But within reason, I agree. I mean
someone could build a really bad reactor that's way too
short or way too narrow or something and that might not
work. But an external reactor is a very simple thing -- a
box or cylinder with some plastic stuff or rocks in it to
diffuse the water current, water inlet and outlet fittings,
and may (Aqua Medic) or may not (Tom Barr's design) have a
CO2 inlet fitting. The biggest diff between an external
reactor and a canister filter as a CO@/water mixer, aside
from the filter media, is that the reactor needs to have
water fed in at the top and outlet at the bottom (that's
what traps the CO2) -- canisters usually have the outlet at
the top to ensure that they burp any bubbles that collect.

> an
> airstone or such device. How good a job a cannister
> filter does in
> comparison I have no idea. Could C02 bubbles get trapped
> somewhere in the
> filter and not get absorbed? Like air gets trapped?
> 
> >>I didn't think he meant that, but you're right. Surface
> turbulence can knock an awful lot of CO2 out of the
> water.<<
> 
> There is a difference between water movement and surface
> tension or
> splashing. I think it is doubtfull that a water current
> set below the water
> surface would burn off C02. 

Well, if the CO2 rich water goes across the top of the
aquarium before it get to the other places in the aquarium,
you might be shedding some CO2 into the atmosphere before
it passes by many plants. After all, the atmosphere wants
the CO2 that's in the water.  I point my CO2 enriched water
down. I think Tom has said that he actually puts the spray
bar down at the bottom. That might be for other circulation
reasons, but I like the plants to have first crack at the
CO2 rich water.

> George Booth even claims
> somewhere on his WEB
> site that Bio wheels do not interfere significantly with
> his C02. 

I didn't know he had done anything with biowheels. I ahve
to get back to George and Karla's excellent web site. I
know I'm gong to here from George but here goes: my
measurements must be diff because I had significant diffs
when using biowheels. These were the spraybar type
marineland Biowheels. The underflow type biowheels (such as
on the Penguin and Eclipse Hood filters) might not be as
aggressive at driving off CO2. I've heard that Hovenac
thinks so -- but that's second hand info and I haven't
measured the underflow type.


> If you
> were just bubbling your C02 into the water, like with
> Eheims ceramic
> diffusor, then it may have some affect, but using a
> reactor, minimal surface
> movement wouldn't have much of an affect.
> 

You mean biowheels won't have much effect? The whole point
of the biowheel is to give lots of exposure of the wheel's
surface to the atmosphere, but that's where you don't want
the CO2 to go. I supposed if you sealed them reasonably
well, that would help. The helps with a wet/dry -- doesn't
solve things but helps. So I tried a few simple things like
covering the biowheel chamobers with plastic, foil --
didn't make much of an improvement in CO2 consumption when
using biowheels.

Getting back to methods, I did it three ways:  with
diffuser and biowheels, with enternal reactor and biowheels
and with external reactor and no biowheels. The first was
least efficient use of CO2 among the three ways. The last
was the most efficient, each improvement an order of
magnitude of roughly 100% or more. I started out with 5
pounds of CO2 lasting about 2-3 months, then I doubled
that, then I more than doubled that again with the third
change. Total savings in CO2 costs, roughly $30-$40 per
year (totally dependent on local costs for CO2) -- not much
when I think about what I spend on these tanks.

If others have diff info, I'm glad to hear it. (I guess
George and Karla are one example.) Maybe it'll all get
sorted out or maybe there's too many factor to control.  

Lastly, let me say that I am not saying biowheels are bad.
I think they're fine for aquariums without CO2 injection
and fine for aquariums with CO2 injection if you don't mind
the higher CO2 consumption rate -- and I can think of
reasons why some folks wouldn't mind.

Scott H.

=====
S. Hieber

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