Been thinking of small tanks more lately and I think I see something that might also help those who do not like DIY very much!
For a reactor, we need to add the CO2 into a chamber where it is exposed to the water before it goes into the tank. Grigg's and Cerge's both use this idea but then they take a fair amount of fussing if one is not into the whole DIY thing. Too much figuring on fittings, too much cutting and gluing to make it fly for some so we need to cut those questions down. For small tanks which require low flow anyway and as a way to avoid cutting the flow through our main filter, how about this idea?
The new, cheap, simple filters from Sunsun that are designed for small tanks are really as cheap as most DIY reactors. The Sunsun 602 0r 603( slightly larger) can be had off the auction for 20-30 dollars!
That includes pump, tubing, and plastic parts for about the price of supplies to build a Cerge's or Grigg's but do not require near the level of work.
Buy a 602 and add a fitting to let the CO2 into the top or into the tubing before the top of the canister and run it as a powered stand alone reactor.
Advantages besides price and simple build?
Can be cleaned as it is made to run as a filter, does not cut flow on your existing filter or could be added on tanks using HOB. They also come with a valve which can be adjusted to better match water flow to the amount needed to avoid blowing bubbles into the tank.
The pump on these are down low so that any build up of CO2 in the canister is not likely to create any problems for the impeller or noise as can happen on other filter designs.
This is a link to the filter but not the price I would pay as they can be found much cheaper. As low as under ten dollars if tubing, plastic, or media are needed.
Just a thought to set your mind abuzz!