[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

CO2 setups and Nitrogen uptake

At 03:48 PM 9/28/98 -0400, Jenn wrote:
>I also do not understand C02 reactors/bubble counters.  A man at a pet
>store told me I do not need a reactor, just a bubble counter to get the
>CO2 to disolve into the water.  I can't see how this could be true, but I
>don't really know much about the CO2 system and how all the pieces work.
>Any preferences out there for which brand of reactor/bubble counter to

Well, Jenn, I am in the process of putting together some CO2 systems for
sale.  Now you know my bias because I will share what I have learned so
far.  I suspect you will reach similar conclusions. 

There are two basic systems:

High pressure:  Tank->regulator->check valve->bubble counter->sintered
glass diffuser
This is the simplest and cheapest.  Our version will sell for $70 including
shipping, without the CO2 tank.

Why we don't sell CO2 tanks:

CO2 tanks are heavy (60# for a full 20# tank) and therefore are
expensive to ship.  The shipping costs almost as much as the tank.
And they are considered hazardous materials because of the pressure
so they are even more costly to ship.  Better to get one locally.
That way you can also be sure your local guy will service it.

How to buy a CO2 tank.

There are two main sources of CO2 tanks:  welding supply companies
and beverage industry suppliers (for carbonation of soft drinks).
Generally, a tank costs about $50 for a 5# tank and $75 for a 20#
tank.  Some suppliers also rent tanks.  $1 per month is a frequent
figure.  You may decide it is more economical to rent.

CO2 comes generally from the same source as your tank.  A refill of
20# is about $15, 5# costs a little less.  You usually exchange your
tank when you refill.  For this reason, it is perfectly OK to start
with a used tank that has been checked out for safety by the seller.

A little CO2 goes a long way.  One pound of CO2 is about 60 gallons
of gas at room temperature and pressure.  That will supply most tanks
for about a month.  Two gallons a day is a heck of a lot of CO2.

and Low pressure systems:

Tank->regulator->needle valve->check valve->bubble counter->reactor

These systems are more expensive, I think ours will end up costing about
$85 without the tank.  We will be making our own bubble counter and reactor
as these cost much too much commercially.  The low pressure systems will be
ready about Christmas, I think.

Anything else I can tell you?
Writing on Nitrate reduction, Frank I. Reiter said:
>>  Denser planting may help, if the tank density is not
>>already maxed out, as might the addition of a few fast growing plants if the
>>tank includes mainly slower growing ones.  Addition of some other limiting
>>nutrient might also enhance nitrate uptake.
Karen Randall replied:
>This may be true in cases where you have a slightly elevated slowly
>creeping nitrate problem.  The person who wrote in was, I think, running at
>60 ppm nitrate.  You're going to need a _boat load_ of fast growing plants
>to keep up with that input.

Karen, I find that floating plants do a pretty good job of stripping N at a
pretty high rate.  Back when I had a ton of fish in a 50 gal, I was tossing
2-4 POUNDS of frogbit a month.  I have to believe there was a lot of N in
that frogbit.  I also ended up with leaves the size of a 50 cent piece!

Dave Gomberg, San Francisco            mailto:gomberg at wcf_com
FormMaestro                              <http://www.wcf.com>