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RE: Dave: On Trickle Filters and CO2 Loss

Date: Fri, 3 Jan 2003 11:11:06 +1100
From: "Adam Shaw" <adams1 at comcen_com.au>
Subject: Re: Dave: on Trickle Filters and Co2 loss.....

>Date: Wed, 1 Jan 2003 10:52:25 EST
>From: Dgrim62 at cs_com
>Subject: Re: Trickle filters and CO2 loss

>This discussion comes up a couple times a year, as anyone who has been
on >the list for a while knows. 
>If memory serves, the inevitable conclusion to most of them is: "CO2 is

>cheap, don't worry about it."

Gee Dave, don't know whether to thank you or not for that one.

For one, Co2 is not cheap where I am - I pay $40aus for a refill.
Aquarium products in general may be cheap in the US (I assume you are
from US), however I can assure you - other places in the world pay quite
large amounts for most of what you take for granted as dispensible.
Anyway - the hassle of having to disconnect the cylinder and have the
tank without co2 for a day - better to minimize the frequency of that
happening. I would not be asking the question in the first place if I
was not in *need* of a constructive answer, or ideally a foolproof
'solution' to it (if such a solution existed).

Secondly, excuse me for asking the question - I am sure it is not hard
to scan over the posts you are not interested in and move on to the ones
you are interested in, rather than reply in an unconstructive way.
Besides, isn't that what the APD is about - new members, old members,
professionals and amateurs alike to 'discuss' and learn together. If the
same topic comes up again then so be it - ignore it and move on if you
are not interested.


Hi Adam,
I'm sorry if I came across as flippant in my reply. I posed the same question 
as you a couple years ago, and I got basically the answer I gave to you.

How is this: 

You will probably have some outgassing as the result of water turbulence in a 
trickle filter. In the US CO2 is cheap, about $13 an exchange for a 20# tank 
in my area, which would last maybe a year or so. Certainly an issue, though, 
if it is expensive in Australia.

One way to minimize CO2 loss is to have a tight fitting glass top on the tank 
and also on your trickle filter. I have open top tanks for temperature 
control, and since I have cheap CO2 it is not an issue for me. I use 
cannister filters so no outgassing there either.

Another way to minimize CO2 loss is to have minimal surface turbulence in 
your tank. I point the cannister returns downward to avoid surface ripples, 
so that would lessen CO2 loss a bit.

For your trickle filter I can suggest a couple ways to avoid offgassing, all 
aimed at making the water flow smoother through it without turbulence. I kept 
reef tanks with trickle filters for a while, and did these to quiet the water 
flow, but the end result will work to reduce offgassing as well. If you use 
plastic media you might want to remove it and try a submerged sintered glass 
type like what Eheim sells. The water cascading over wet-dry type biomedia 
probably frees up much of the CO2 that would otherwise stay in the water.

This last method really worked to reduce noise, and would help a lot to 
reduce offgassing, I'd think. You probably have a plastic top to your wet-dry 
that water enters thru after leaving the tank. Remove the trickle filter drip 
tray if you have one. Plumb in a barbed fitting under the top and then run a 
vinyl tube to the bottom of the wet-dry so the water leaving the tank 
basically travels thru tubing to the bottom of the wet-dry and doesn't splash 
into the water already in the sump. This makes the water entering the trickle 
come in below the water level in the sump. Much more quiet and no splashing.

I personally don't think you'd harm your tank much if it went a day without 
CO2, but what I do for the inevitable C02 cylinder replacement is I keep 5# 
tank in my basement and hook it up when I have to do a swap out. I exchange 
my 20# tank for another at my local gas supplier, so I don't have to leave 
the tank to be refilled. Maybe this is not an option for you in your country.

I hope you find this reply more constructive than my first. No offense 

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