Quick update, my azolla is getting very dense and the water is deep green with healthy algae, the duckweed is nitrogen starved

[jaykrown@lemmy.world]

I've been turning the pump on to oxygenate for about 10 minutes a day, seems to be working fine, no gross smell or rot. The azolla is starting to look matted, growing on top of each other thick. This is my suspicion, that azolla per horizontal space, can actually take up more mass than duckweed, given that duckweed is very thin and flat, while azolla is thicker and "stockier".

So still, even though the duckweed competes strongly with the azolla, I've completely stopped putting nitrogen in, and only put phosphorous, potassium, and iron chelate. The duckweed is still mixed in there, but severely limited in size due to lack of nitrogen, which is where the azolla is succeeding, although the azolla grows slightly slower.

If the goal is to get the most consistent robust growth just using P, K, Fe, then azolla is the massive winner by far. If you have any questions please let me know. The biggest insight is that the azolla started growing faster around 5 pH (slightly acidic), better than when it was around 7 pH (neutral).

I also suspect that the algae in the water has been fixing all the nitrogen in the water, further starving the duckweed, while the azolla has been minimally impacted by it.