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Gary Pimm


  1. CO2 addition rate
    by (Gary R Pimm) (26 Aug 93)

CO2 addition rate

by (Gary R Pimm)
Date: 26 Aug 93

In article <> writes:
>George Booth (booth-at-hplvec.LVLD.HP.COM) wrote:
>: Make sure the output of the regulator is in the 10-20 psi range.  They don't
>: do well with very low pressures.  
        More excellent info from  George deleted....

>: ------
>: George
>depending on how many fish you have in your tank it may make sense to
>shut CO2 off during the night; otherwise pH may drop quite a bit if you
>keep adding it. There are electric valves that can be switched on/off
>with your light. 
        More excellent info from Uwe deleted...

I have run 3 different tank setups with manual CO2 injection over the last
2 years.

Tank 1 was a standard 55 gal with ~4 sq ft surface area, open top,
submerged inlet and outlet on the canister filter systen, low surface water 
curent, CO2 injected into the input of the filter system. Lighting was
160 watts of mixed flouresent.

Tank 2 is a 60 gal with ~5.5 sq ft surface area. all of the other details are
the same as tank 1. Lighting varies with local weather conditions, tank is 
in front of a large south facing window. Their is 40 watts of philips agro
for lighting in the evening.

Tank 3 is a 10 gal with about 90% of the top covered by the hood, surface
skimmer on the filter input, low curent at the surface of the water with the
exception of the water near the skimmer, and a CO2 reacter in the filter.
The filter is a aditional glass box (sump) that is glued to the back of the
tank. The height and width are the same as the tank and the front to back
depth is the same as an aquaclear 500/2000 sponge. Their are 2 1.25" holes
drilled through both the tank and the sump. One feeds water trom the skimmer
box into the filter sump the other returns water to the main tank. The water
is punped back into the main tank by a ancient aquaclear 200. 90% of the water
is pumped into an under water spray bar that is at the bottom of the tank 
blowing twards the front and the other 10% goes into the CO2 reactor and back
into the sump. Lighting is 26 watts of 4100K tri phospher (2 pl13's) and 15
watts of penplax aquarialux.

Tank 2 is the only one in operation now. I had to shut down the others when we

I tried to keep all the tanks at 18ppm CO2. In tank 1 it took about 48 bubbles
per minute, in tank 2 it takes about 60 bubbles/min and in tank 3 it also took
about 48 bubbles/min. 

The CO2 injection in all 3 tanks was on all the time. I was not able to measure
any pH shift between before lights went on in the morning and at the end of the
day. Granted the only test I have uses bromo.... blue indicator and has lousy
resolution. It just showed that their was not a large shift.

I think that the fact that the 10gal with the surface skimmer lost as much
CO2 to the atmosphere as the 55gal with submerged inlet shows that the water
movement plays a large role in how much CO2 is lost. The fact that I don't
see a large shift in pH says that the CO2 lost to the atmosphere is >greater
than the amount used by the plants. Don't get me wrong, I do want to get 
a test kit or pH pen that will set me see the shift caused by the plants 
using the CO2.

My tank that sits in the south window is by far the most succesfull tank I 
have run. The sun was out yesterday and WOW! Their were so many streamers
of oxygen coming off the plants that you could loose some of the smaller fish
in the tank. I think the fact that we switched to Duplaplant and Duplaplant24
for our fertilizer 1 month ago has something to do with this. (Shameless

The only way that I could see anyone having a problem with manual CO2 injection
would be if- Very heavy planting
             Very bright lights
             Very tight fiting hood that can concentrate the CO2 level in the 
                air space directly above the tank.
This type of a setup would be more dependant on how much CO2 the plants use
and not have the stablizing effect of losing CO2 to the atmosphere.

Enough of this semi mindless wandering.
Gary Pimm

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