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It's hard to know what stage of decomposition a purchased soil is in. Cow or any kind of manure might be fine if it is well-decomposed. Earthy smell is always good.

Oxygenation can change everything. A soil sitting in a jar or a tank with no water movement can easily go severely anaerobic. In my tank setups with soil underlayers, I always had water circulation via a pump filter or gentle air bubbling.

Look for potting soils sold for growing houseplants, cactus or other slow growers. Avoid packaged soils designed for growing vegetables, lawns, roses, etc. A low NPK rating is another clue. Look for the soil with the lowest N content. The goal is to find the least fertile soil and then use it sparingly.
 

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Hard to say, because I don't know what those numbers mean and I see lots of variability. For example, the 0.52-1.61 nitrogen? Is that %. If so, it is very high. The soil (MGOC Potting Mix) that I used for my successful shrimp bowls contained 0.10 % nitrogen. [It had an NPK "rating" of 0.10, 0.05, and 0.05 (i.e., contained 0.10% N, 0.05% P, and 0.05% K).] Without other input on composition on the brand you have displayed, I would not recommend it. You would have to mineralize the heck out of it before putting in a tank. (If you go this route, see Michael's mineralization procedure.)

Your kitchen compost appears to be working very well. This jives with my results. Immediate good growth, clear water, and a hint of tannins (yellow tinged water).

I would not fault a brand because it does not advertise its composition. Look for bagged stuff in garden centers designed to grow indoor houseplants. Surely, storekeepers know which of their brands are working best for their houseplant customers. Folks, this is not rocket science or require technical wizardry. People have been growing houseplants for centuries.
 

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Oxygen is the key to keep it from smelling. This can come from plant photosynthesis, water movement, poking substrate, etc. Your choice...
 

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I looked back at photos of your jars. Looked wonderful. Huge plant biomass. Clear water. What has changed?

If the plants are doing well, I would not worry about substrate bubbling. The goal is to have good plant growth not to have a sleepy substrate.

Do you have animals in the jar?

Maybe a new photo to compare plant biomass with previous photo? Has growth been good enough that you have been pruning plants since last photo?

I would wait on changing anything. In general, hardwater is good.
 

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Lovely! Aside from the pleasure of witnessing a hard-won success, the results are very interesting.

R.O. water has no nutrients, so the soil and fishfood alone is releasing enough into the water for your plants. A freshly submerged soil will release plentiful Ca and Mg (my book, p. 131, Fig VIII-6).

It is possible that your tapwater contains high levels of sulfates. The sulfates would percolate into the soil where bacteria would convert them to toxic H2S. (Hard waters from a coastal city with a seawater input would be expected to contain high sulfates.)

In any case, your results are wonderful and worth celebrating. Thanks for posting!
 
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