Re: CO2 reactors in sump, wet/dry filter

[Thomas Barr <tcbiii at earthlink_net>]

Scott, it's difficult to explain verbally here. I think this is were the
confusion lay. 

The design is similar to that of an external reactor, but the bottom portion
has no back pressure since it simply falls right into the sump. The reactor
can be above the water level on the side or sitting on the bottom of the
sump etc. So it can be sort of external(hang on the side of the sump) or
internal(sitting into the sump) really. You'll have a longer return tube if
you fed it back to the sump pump return.
 
If you use an external without a sump, the water needs to be forced back and
up to the tank. This reduces flow rate.

If you are branching and teeing off a return pump that has plenty of excess
flow, and you use this flow, then reduced flow not an issue.

You can make a U shaped loop in the return pump for the CO2 reactor if you
want. But unless you have a solenoid(40-80$), the CO2 cannot be turn on or
off at night or used with a controller. You also will need and should have a
GOOD check valve due to the back pressure created in the pressurized set up.
These are two things folks have issue with but if you are a good DIYer
generally you wouldn't want to buy a solenoid/check valve but you might not
care about having the CO2 on 24/7 or not using a controller etc. The design
I use and many other makers allows for controllers/semi automated use
without solenoids/check valves in some cases.

A tee off design from the return pump might be suitable for some folks. I
don't like solenoids/check valves and want to be able to turn the CO2 off at
night like many folks. Using a powerhead to accomplish the same thing is a
better and less costly design. The added impeller atomization of the CO2 gas
prior to going to the reaction tube improves the efficiency and reduces the
size needed for the reactor.

It gets down to the right design for the user's desires.
I was thinking about comparing an independent hang off the back external
model vs a sump model sitting in the sump.

Regards, 
Tom Barr