[mistergreen]

Soil high in organic matter will always go anaerobic. You can help by sifting out big bits of organics and adding in sand to reduce the organics.

 

[mistergreen]

No need to add bone meal and fish meal in the soil. It’s a recipe for disaster. The smell is awful too.
You can add a little bit of limestone or coral to add calcium and balance the pH in the soil.

plants are an important ingredient in a dirt tank. You need plants.

 

[mistergreen]

You can always add a little root tabs in the soil if you worry about nutrient levels. I’d pick one that doesn’t go anaerobic in your test.the sand cap is a bit high though. It should only be 2 cm.

 

[mistergreen]

Seems like adding bone meal and manure are a hassle.
if you’re seeing NO3 => NO2 reaction, there might be anaerobic conditions in your substrate.

 

[mistergreen]

Poke your substrate with a stick and smell if the bubbles smell like rotten eggs. If not, it’s CO2 bubbles.
Your plants look great though.

 

[mistergreen]

Hydrogen sulfide smell indicates anaerobic conditions in the soil. Poking introduces oxygen into the area which helps. Plants have a difficult time growing in anaerobic soil and hydrogen sulfide is toxic to fish in large enough quantify.
It sounds like you’re good.

 

[mistergreen]

The Forrest soil looks pretty low on organic content. You wash away the clay content it seems. It looks really natural though.

 

[mistergreen]

Yeah, you can mix in the new compost soil into the forest soil. No need to add anything else. Compost is rich in N & P.

 

[mistergreen]

Pull out the affected plant to see if the roots are black or melted. It’s a sign of anaerobic soil I mentioned.

 

[mistergreen]

The bubbles with no smell is CO2. You want to leave that alone for the plant.
The anaerobic tank, you want to poke everyday to introduce O2 into the soil. Hopefully the condition goes away over time.