We have a moderately successful family fish tank: The fish seem to survive, the plants do not.
(Also we’re really good at growing algae, and may start feeding it to the children.)
With a coding problem, you Google it and get several excellent solutions. With a fish tank problem, you Google it and get several excellent solutions that contradict each other.
So the excellent solution we’ve chosen to make the plants happy is to add carbon dioxide to the tank. Plants need it, and one of my favorite in-store tanks uses it. So it's settled.
I thought I’d need to pick up a heavy tank of CO2, like when I rented a tank of helium.
Turns out you can coax yeast to make it for you. This Instructable describes how, and is what I used to make ours.
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