Hi Roberto; sort of a late reply. I use chem fertilizers for seedlings indoors.
And Try to use Natural fertilizers outdoors, for food production!
When I use organics indoors, I get those little yeast gnats.~~~
I have issues a lot with chemical fertilizers locking up nutrients. I think it is Phosphorus building up and blocking trace elements for Chlorophyll production.
Sometimes I experiment with very low Phos fertilizer, and use a colored marker in one corner of the pot. Then I always give the phosphorus in that same spot, hoping the rest of the soil keeps emitting nutrients normally.
Fossilized Seabird Guano: I have had really good luck with Fossilized Seabird Guano. It's a good natural Phos' source. But I think it has something very alkaline in it. And if it is really coarse grained; perhaps the nutrients are not available for a long long time. Powdered mixes w water - but it can make the water pH very high.
I have had the best luck with Dr. Earth brand organic fertilizer. But $10.00 for a cereal box full is V expensive. I used jobes, but got tall tall veggies, and little flowering.
The fert with the inoculants, seems to help reduce root-rot a lot. Low numbers are safer .. high numbers might be un-fermented proteins. That will produce excess ammonia breakdown. And deplete root O-2 availability.