I never boil
I never boil the water, just use tap water, not hot, not cold, just skin temp-ish.
If the mix smells "like death" then you need to clean everything well, you've gotten some bacteria in there that is not good.
If you shake the unit to mix, you risk getting yeast in the tubing and you will have more yeast-snot form on the end of the tubing in the tank where it can interfere with the bubbles staying on the ladder. If you get much snot, clean the entire cap and tubing well in hot water.
Check your phone book for home beer brewing supplies, you may be surprised how many there are. They will carry probably a dozen or more types of yeast and various yeast nutrients that have assorted chemicals. I tried testing a few and gave up. Some like cold, some tolerate heat, some float as they are used up, others fall to the bottom as they are used up. Bread yeast plus baking soda works fine. Wine and beer yeast don't seem to like baking soda, I suspect they have different tolerances for alkalinity/acidity. The mix goes very acid as it is used up -- do not open a canister and add baking soda after it has been going! (scenes from the old erupting volcano trick)
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110G, 10 adult discus, barebottom with plants on wood
58G, 3 adult discus, barebottom with plants on wood
59G thickly planted tanks, rummey nose tetras, kuhlies
300G goldfish pond outside