Thanks for the compliments Clinton. (Sound like I am talking to myself!)
ops:
I say this little reactor can handle a 75gal tank but it's a function of what the livestock's calcium demand is. The chamber holds about 1.5 containers' of ARG media. The effluent drips at a rate of about 2-3 drops per second and it is around 45+/-dkh. My tank is 40 gal and the [Ca] is at 430+/- ppm.
I have another idea for diy reactors... An older model fluval canister filter can easily be modified into a reactor. Just loop the intake and output with some rigid tubing. The feeds for CO2, water in and effluent out can be drilled into the canister top or the rigid tube.
cheers
Clint