RE: CO2 Setup

["Eric Wahlig" <ewahlig at earthlink_net>]

Giancarlo,

I don't think anyone's responded to your post yet, so, I'll give it a go. I
have not used either of these units but they seem very similar to each
other. I can not see the cylinder connection in either photo and I'm
assuming its directly behind the regulator. For US cylinders this needs to
be a CGA-320 style fitting and a special (but commonly available) sealing
gasket washer is used with it. Dual gages are nice as the tank pressure
gage will always read about the same (around 800 PSI) until the tank has no
more liquefied CO2 in it. It will then start to drop and a 5# cylinder
doesn't take long to go empty from this point. You might get a couple of
days out of it depending on your injection rate. So, this feature can give
you some notification that you are running low on gas. You can always weigh
the cylinder and subtract the tare weight (should be stamped TW on the
cylinder) to figure about how much you have left.

Hopefully, the needle valve is a good one. By that I mean that it's capable
of fine adjustments from nearly off  to probably way more than you'll ever
need. Many needle valves are not meant to stop the flow so you may not be
able to turn them off completely and doing so can damage them. However,
they can limit the flow so much that even a very small amount of water
pressure pushing back against the gas flow will stop it. Hopefully, this
valve will provide this kind of adjustment; from "effectively off" to lots
and covering, smoothly, all the flow rates in between. Because I don't use
either a timing system (with a solenoid valve) or a controller, I think
this is the most important component in the CO2 system.

I would opt for the diffuser over the bubble counter if you have some way
of measuring either the pH, KH, or CO2 level to find out something about
how it will affect your aquarium. In some filter systems, like back
filters, I just watch the end of the clear filter intake tube to see if the
CO2 is bubbling steadily through it. On canister filters I just listen for
the steady "whoosh" of the gas bubbles being drawn through the impeller. On
the wet-dry I watch the bubbles as they are sucked into the pump. In any
event, the exact bubble count is not critical unless you are using very un
buffered water. Getting the gas to dissolve in the water is more important
than counting the bubbles.

The 5# cylinder should measure about 18" tall. Better give it a couple more
inches to account for the regulator gages. Also make sure you secure the
cylinder. I usually just strap it to one of the aquarium stand legs. You
don't want it to fall over. You can tilt the tank a few degrees to get more
clearance as long as you can firmly and safely secure it in that position.
Do not lay the tank down while it is in use. This causes liquid CO2 to
decompress inside the regulator instead of inside the cylinder and will not
only ruin the regulator but can cause catastrophic failure as well. The
best place to get the cylinder may be locally. If you have the time to
check out garage sales, auctions, or flea markets these can be the best
deals. You need to check the latest test date (stamped on the cylinder) and
be sure the valve is a CGA-320 type. Find out from the gas supplier what a
hydro test will cost if the tank is out of date. The newer aluminum
cylinders cost more but are a lot lighter to ship, so , the shipping cost
is less than for a less expensive (but heavier) steel cylinder. I live in a
metropolitan area so I have an exchange account with a local industrial gas
supplier. That way I don't have to wait to get a refill or worry about when
the cylinder test expiration date is.
 
--- Eric