Okay, to revisit the Low-Tech Challenge.
Here's my plan so far.
*I plan on using a 12-inch Cube aquarium.
*Powerhead / sponge filter attachment. (basically just a pump).
*No Co2 or excel.
The Substrate System Plan:
Since I will need to rely even more so on the substrate for biological filtration, I'll use power sand with the addition of Bacter 100 and Clear Super. The actual substrate itself will likely be something like just sand or oiso gravel.
I don't want to overload the substrate with nutrients - since it will be a precise balance game. I can supplement with liquid fertilizers to make up for the gap, or deploy root fertilizers in certain spots if need be. The substrate's most important role at this point will be biological filtration.
The Co2 Plan:
DIY Yeast: eliminated as option, the inconsistency of the yeast system is a problem I don't want to deal with - BBA, namely, would show up with such a system. Also, it wouldn't be able to turn off at night, preventing oxygenation.
Excel: eliminated as a primary option, may be a secondary option, but the fact that it dissolves after 24 hours is a bit concerning. I may come back to this one, but I still consider it a last resort.
Excel is kind of an emergency go-to for me; if a tank is just way out of whack, then it's a good back up. Otherwise it's not really necessary.
The current plan is to basically do small water changes daily using carbonated water. We'll see how that goes.