CO2 diffusers vs. reactors
 

After listening to a lot of opinions, I've decided to stick with my
30-35% weekly water changes (at least until I get a python), but to add some
CO2 for my high-load 55 gallon (80watts). I made up a DIY CO2 system with
one 2L CO2 bottle in order to go slowly before adding a second CO2 bottle
(through a t-joint that currently has one arm sealed). I had problems with
the seal at first, but then just made a smaller hole on another cap, so I
now have plenty of CO2 coming into the tank through 1/4" silicon tubing.
In the short term I got an airstone (useless) and a clear plastic bell
to allow passive diffusion. This isn't working too well, as the CO2 builds
up and occasionally bubbles to the surface when the bell fills (the bell is
right beside my large HOB filter intake, I also have a second smaller HOB
filter on the other side of the tank). So my next step is to find a good
way of diffusing the CO2 into the water (I keep the water level high to
reduce surface agitation). I like the ease of diffusion compared to reactor
methods, especially since my wall plug is already bearing a heavy load! So
does anyone know of a good diffuser I could build or buy (in Canada)? I'm
looking at one from Big Al's:
http://www.bigalsonline.ca/catalog/p...3&pcid 1=3349

Does anyone have any experience with how efficient these style diffusers
are? Anyone know of good data on how efficient the various diffusion
methods are? I don't need ultra-high levels of CO2, but I haven't seen any
significant change in my pH or plant growth under my current (and admittedly
half-assed) set-up. As I said before, I prefer the diffusion method, but
I'm open to building/buying a reactor if that's truly a much better way of
going about it. I certainly don't see my current bell set-up doing much if
I add a second DIY bottle of CO2! Thanks,

Tony

"Tony Volk" wrote in message
...
Does anyone have any experience with how efficient these style diffusers
are? Anyone know of good data on how efficient the various diffusion
methods are? I don't need ultra-high levels of CO2, but I haven't seen
any
significant change in my pH or plant growth under my current (and
admittedly
half-assed) set-up. As I said before, I prefer the diffusion method, but
I'm open to building/buying a reactor if that's truly a much better way of
going about it. I certainly don't see my current bell set-up doing much
if
I add a second DIY bottle of CO2! Thanks,

Hi Tony,

I don't have any pesonal experience with this type of reactor, to be honest,
but I have my eye on one at the LFS which is very similar, and about the
same price.

What I have noticed about this type though is that two would be needed at
each end of a tank 50gal or larger.

I am currently using an active reactor, following the Tom Barr design, and
previously to that I was just feeding my dual bottle bubbles directly into a
venturi input of an internal filter.

It seems to me from using these two methods that one factor is actually
critical - and that is the the CO2 bubble has to spend as much time in
contact with the water as possible to diffuse - in the pre-Barr system this
used to happen by the output smashing into the substrate and then being
pushed around the tank to the input of the first filter, where the impeller
would break up any remaining bubbles and push them back towards to filter
with the CO2 on the venturi.

What I have noticed with the Barr Reactor is that while the bubbles are much
finer, the dissolved output water isn't getting as far around the tank as
previously. Short of modifying the main filter to put out a really strong
circular flow around the tank I can't seem to get this reactors output to go
as far.

I am still experimenting with different diffusion systems myself. My
instinct is to just whack the CO2 line onto the venturi of the power head to
get it around the tank, but I think the reactor actually does a great job of
making diffusable sized bubbles.

I guess what I'm getting at is that it's all a matter of experimentation and
customisation for the tank. If you do go with the product you provided the
link for, I'd say you'd need two with a bottle on each one - and get the
water moving as much as possible.

Oz

--
My Aquatic web Blog is at http://members.optusnet.com.au/ivan.smith

Tony

"Tony Volk" wrote in message
...
I certainly don't see my current bell set-up doing much if
I add a second DIY bottle of CO2! Thanks,

Tony

Try 1 gallon juice bottles. Make you health ;-) and the cat can't tip
them over as easily. The bigger allow installing brass bayonet fittings.
Much better seal. I get them with an O-ring and brass nut for a couple of
dallors a set at a plumbing supply store. I run three 1-gallon jugs per 55
gallon tank.
Bob

"Tony Volk" wrote in message
...
After listening to a lot of opinions, I've decided to stick with my
30-35% weekly water changes (at least until I get a python), but to add
some
CO2 for my high-load 55 gallon (80watts). I made up a DIY CO2 system with
one 2L CO2 bottle in order to go slowly before adding a second CO2 bottle
(through a t-joint that currently has one arm sealed). I had problems
with
the seal at first, but then just made a smaller hole on another cap, so I
now have plenty of CO2 coming into the tank through 1/4" silicon tubing.
In the short term I got an airstone (useless) and a clear plastic bell
to allow passive diffusion. This isn't working too well, as the CO2
builds
up and occasionally bubbles to the surface when the bell fills (the bell
is
right beside my large HOB filter intake, I also have a second smaller HOB
filter on the other side of the tank). So my next step is to find a good
way of diffusing the CO2 into the water (I keep the water level high to
reduce surface agitation). I like the ease of diffusion compared to
reactor
methods, especially since my wall plug is already bearing a heavy load!
So
does anyone know of a good diffuser I could build or buy (in Canada)? I'm
looking at one from Big Al's:
http://www.bigalsonline.ca/catalog/p...3&pcid 1=3349

Does anyone have any experience with how efficient these style diffusers
are? Anyone know of good data on how efficient the various diffusion
methods are? I don't need ultra-high levels of CO2, but I haven't seen
any
significant change in my pH or plant growth under my current (and
admittedly
half-assed) set-up. As I said before, I prefer the diffusion method, but
I'm open to building/buying a reactor if that's truly a much better way of
going about it. I certainly don't see my current bell set-up doing much
if
I add a second DIY bottle of CO2! Thanks,

Tony


Tony,

I used to do the DIY yeast CO2 injection directly into the uplift tube of my
HOB filter for my 39 gal tank. With that setup I was able to achieve about
18 ppm CO2 saturation. I found that I could get a good 8 days of production
from a 64 oz mixture (juice bottle) and so I would change the mixture out
every weekend with a new batch that was started 24 hours prior (new batch
usually mixed up on Friday night). That way, every Sat or Sun the aquarium
got a new charged up batch of CO2 that *could* last 8 days.

I upgraded to a 70 gal tank and tried to keep up the CO2 saturation with two
bottles of DIY yeast mixture and couldn't do it. To this day I do not know
why but the advice on this newsgroup was that beyond 39 gallons, DIY is not
worth it.

On my 75 gal I had about 2.5 wpg of lighting and so stable CO2 was crucial
to steady growth and nutrient uptake. As you can imagine, I had a
disastrous break out of algae due to fluctuating CO2 and corresponding
fluctuations of nutrient uptake by the plants. I broke down and spent US
$125 for a pressurized system and have never looked back. I recommend it if
you can afford it.

As far as a reactor goes, I had the best success with a power head and
gravel vac tube combination. There are many sites that describe the DIY CO2
reactor. The best efficiency was when I angled the vac tube at about 45
degrees. I think the reason for this was two fold. 1) the bubbles seemed
to stay in the reactor tube longer at this angle and 2) the angle promoted
the dispersion of the saturated CO2 water around the tank. Vertical seemed
to concentrate the CO2 in only a portion of the tank.

You might experiment with your DIY CO2 setups using a power head reactor but
I believe your success will be marginal because of the size of your tank.

HTH,

DJay

I used to do the DIY yeast CO2 injection directly into the uplift tube of
my
HOB filter for my 39 gal tank. With that setup I was able to achieve
about
18 ppm CO2 saturation. I found that I could get a good 8 days of
production
from a 64 oz mixture (juice bottle) and so I would change the mixture out
every weekend with a new batch that was started 24 hours prior (new batch
usually mixed up on Friday night). That way, every Sat or Sun the
aquarium
got a new charged up batch of CO2 that *could* last 8 days.

Thanks for the replies everyone. How long did you inject into your
filter input tube? I've heard that the bubbles can play havoc with the
filters propellers and rubber fittings, plus they make more noise. But that
most mostly with injecting directly into the input and skipping the tube (at
least, that's what I remember reading). That was one of my first instincts,
but I'm cautious about damaging the filters. On the other hand, did you
notice if the increased suction from the filter input had any negative
effects (e.g., did it ever suck any fluids from the CO2 canister when its
pressure dropped towards the end)? Cheers,

Tony

p.s.- I've been calculating my water changes based on tank size- is that
correct or should I calculate the % based on the actual volume of water in
my tank (e.g., my 55 gallon tank probably only has about 45ish gallons of
water, so a 30% change is actually a 35% change, etc., meaning I'm changing
35-40% of the water each week-closer to Tom's suggestion).

Tony Volk wrote:
Does anyone have any experience with how efficient these style
diffusers
are?


Tony, I'm running that exact same product on my 55g tank with
pressurized C02. At up to 80-100 bubbles per minute, the diffuser was
about 90% efficient with a very small amount of bubbles being able to
collect at the top only to finally escape to the surface. I was able
to obtain about 15-20ppm C02 at this rate. Since then, I've jacked up
the bubble rate to 130 bubbles per minute and calculate the C02 at
26ppm which I like better. At this rate though, more bubbles collect
at the top of the unit and escape.

Overall, my evaluation of this ladder is very positive. The bubbles
start out at the bottom at about 1/8 or 3/16 inches diameter. As they
flow up the ladder, they gradually reduce in size to about 1/32 in dia.
It reminds me of the incredible shrinking machine they used to have at
Disneyland. :)

steve

"Tony Volk" wrote in message
...
I used to do the DIY yeast CO2 injection directly into the uplift tube of
my
HOB filter for my 39 gal tank. With that setup I was able to achieve
about
18 ppm CO2 saturation. I found that I could get a good 8 days of
production
from a 64 oz mixture (juice bottle) and so I would change the mixture out
every weekend with a new batch that was started 24 hours prior (new batch
usually mixed up on Friday night). That way, every Sat or Sun the
aquarium
got a new charged up batch of CO2 that *could* last 8 days.

Thanks for the replies everyone. How long did you inject into your
filter input tube? I've heard that the bubbles can play havoc with the
filters propellers and rubber fittings, plus they make more noise. But
that
most mostly with injecting directly into the input and skipping the tube
(at
least, that's what I remember reading). That was one of my first
instincts,
but I'm cautious about damaging the filters. On the other hand, did you
notice if the increased suction from the filter input had any negative
effects (e.g., did it ever suck any fluids from the CO2 canister when its
pressure dropped towards the end)? Cheers,

Tony

p.s.- I've been calculating my water changes based on tank size- is that
correct or should I calculate the % based on the actual volume of water in
my tank (e.g., my 55 gallon tank probably only has about 45ish gallons of
water, so a 30% change is actually a 35% change, etc., meaning I'm
changing
35-40% of the water each week-closer to Tom's suggestion).



You should calculate the volumn based on your actual volumn. E.g. (total
volumn - substrate etc) * 35%.

I'm not exactly sure of your question regarding the HOB intake tube and the
DIY CO2 injection... What I did was rubberband the air hose (coming from
the DIY CO2 juice container) to the intake tube of my AquaClear filter so
that the opening of the air line tubing was just below the intake. I'd also
cut the airline tubing so that it was at a 45degree angle. By putting the
angle cut side toward the intake tube the bubble would come out right next
to the strainer on the intake tube and that would help insure that the
bubble was sucked up into the filter. I never had any problem with the
filter at all. There was an audible "crashing sound" as the bubble was
smashed by the impeller. I also kept the water in the tank very high as to
accommodate the return from the filter so that there was not a lot of
surface agitation (I think you mentioned that you were already doing this).
When the DIY yeast mixture was due to be changed out, I simply unscrewed the
juice cap (with the tube coming out of it) and screwed it onto the new DIY
yeast mixture in the second juice container. Worked great.

HTH,

Djay

I note with Barr reactor, when the bubble is more sophisticated, soluble in water is not getting the output as close to the tank as before. Major changes to the short filter out really strong flow around a circular tank, I can not seem to get this far from the reactor output.

I accept noticed with the Barr Reactor is that while the bubbles are much finer, the attenuated achievement baptize isn't accepting as far about the catchbasin as previously. Short of modifying the capital clarify to put out a absolutely strong circular breeze about the catchbasin I can't assume to get this reactors achievement to go as far.