with 42 gallon tank i wouldn't worry about metering CO2 with one DIY bottle.
just let the bubbles get picked up by the 2026 intake and you should be
fine.

i doubt that you'll ever see 20ppm.

jtm

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"Prakash" wrote in message
...
Hi,
I've just set up my tank. 42 uk gallons, Eheim 2026 filter, sand substrate.
The ph is 8.2 (seems to hover at 8.0 and thereabouts). Quite a few plants
(though I can identify only the Cabomba yet), and 6 zebra danios.
I have started building a DIY CO2 system. Following questions:

1. How do I control the flow of CO2. I've put a 2 way gang valve at the
outlet of the generator, the idea being I simply throttle back to the
required level. And then I read this post about exploding DIY Co2 bottles.
Can I use the other valve on the 2 way gang to bleed excess CO2 ? I also
have a non reurn valve after the gang valve.

2. I have designed a reactor using a useless gravel cleaner (useless because
it never worked as advertised!). The design is at the bottom of this post
(really crude diagram, but roughly to scale). The idea is that I can
maintain a column of CO2 in the tube that helps dissolution, and make the
excess bleed out of the hole in the side. If the CO2 dissolves at a faster
rate (or production drops), there will not be a column. Is this likely to
cause a problem ? I plan to put this reactor near the intake of the filter
so there is flow of water around the bottom of the reactor.

Any other ideas on how to control the injection of CO2 will be gratefully
received. I do not want to kill the fish.

TIA,
Prakash.


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/ \---- CO2 Injection here. 4 mm tube.
/ \