"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.


I'd be very careful about trying to control DIY CO2 by restricting the flow
from the generator for the reasons you have outlined. If you are going to
try & do it then I think the way to achieve it safely would be by varying
the contents of the mixture - presumeably either use more (or less) yeast to
try & control the rate of CO2 production. I think trying to restrict the
flow out the bottle would be a recipe for disaster - the pressure will
gradually build up and then , well, Kaboom!

OTOH. I doubt that you would be able to produce enough CO2 out of a DIY
setup (unless you used multiple generators) to cause your fish a problem.
What you could/maybe should do is to install a valve in the line that allows
you to switch over from putting the CO2 into the tank to letting it escape
to the atmosphere. You could then use this at night.

Saying that, I suppose you could use a similar kind of arrangement to try &
control the flow into the tank. If you had a bleed valve that would allow
very fine adjustment, you could maybe control the flow into the tank by the
amount you let escape if you follow me. If you use std airlline fittings I
have a feeling it might be kinda on or off though! Also bear in mind that if
you use std airline (especially the silicone variety - the soft green stuff)
it will leak CO2 itself.

These are some of the reasons I went for a gas bottle system. See my post
yesterday about how to get your hands on cheap bottled CO2 & then maybe look
at what you could do to build your own system. There are plenty of posts in
google about picking up regulators & needle valves etc. The 3.5 kg bottle
that's under my tank (75 UK gallons) will last the thick end of a year I
would guess.

Not as cheap as the DIY version but less mess & hassle and less likely to
make a major mess. I know there are loads of people who use DIY but I
decided it wasn't for me!

HTH

I.