I am now using Tom's venturi design furnished to me by one of the boards gracious members, that esteemed gentleman and fellow aquarist (feverish applause and loud clapping), Cornhusker. Works great!! My previous reactor was a Reactor 200, but it is not as good as Tom's design. My solenoid is not turning on and off as frequently as it did, even with a higher KH setting. Has anyone else had experience with this and how does your reactor compare? As well, I believe Cornhusker made some mods to the original design, so he might want to list the improvements. Sorry to put you on the spot, buddy.
I received the version you made.
The venturi is a bit lower than need be and the burp hole is much higher than need be.
You may wish to lower the pump input and place the venturi slightly above that and then place the burp hole at this same level or slightly lower.
Placing the venturi hole below the pump input is a good idea though since you can directly feed the CO2 in to the pump's impellar with the pump mounted on the side.
It tends to make less noise and seems smoother if there is a venturi on the pump's output, but nothing wrong with feeding it into the pump's intake either.
There are a few modifications that could be done to any design, most are minor.
The biggest issue here is the placement of the burp hole being too high.
The CO2 will burp out before the CO2 gas bubble will ever reaching the low venturi level, it's almost 2 inches away and the pressure from the gas bubble will burp out the gas instead of building it.