"Perfect" Fertilizer?

[HappyGuppy]

 I make my own organic fertilizers for my garden, and even for sprouting (my food).  A common thing for sprouting is to use kelp fertilizer, and some people even use it for their homes.  It's cheaper & super easy to make oneself.   

I had a thought. Why not grind up some dry seaweed from an asian store, blend in water, let sit for a couple weeks, and then use this for fert dosing in tanks.  I can't see why this wouldn't work for freshwater plants too (salt = minimal).  I am trying to grow saltwater macroalgae, and though I have chemical powders I figured that seaweed tea already has *EVERYTHING* that seaweed needs to grow, so no calculating chemical ratios, etc.

I am extremely confident that this should work.  I'm "trying" it myself this week.  Just sharing a new idea.

[HappyGuppy]

Perhaps I should add that dosing would be in drops, and thus should not be enough to negatively affect fish.  I am aware that too much = dead fish.

[HappyGuppy]

I had an additional thought.  Normally when making fertilizers (or even garbage enzyme - google it) I do it in a closed container to get anaerobic breakdown.  Some other things I do for personal consumption (ie vinegars, kombucha, etc.) are more aerobic, but produce more organic acids.  There is a third way, for the minerals mainly, would be to boil it and use the "tea".  A fourth way would be to simply grind it and just sprinkle it in - if fish/animals eat it, or bacteria in the tank, the same goal is produced: nutrients.

I think that overall the simplest solution might be the best (K.I.S.S. principle).  I think that option 4 may be the one I'll use.  I'll simply grind in a blender to a powder some kelp, and just add a pinch into the tank every few days, kind of like feeding flake food.

I don't plan to use much as I'm not going for a saltwater equivalent of a CO2 injected high light & fert planted tank.  The algae supplement, in my theory, would provide the macroalgae nutrients that might possibly be the limiting factor for their growth (ie. is there enough phosphates & iron in the fish foods?  Other traces?).

Hmmm... while writing the above line I just had a thought... why not use some of the existing plant matter from the pruning for this.  I often did that before with my freshwater tank - nuking some excess duckweed or other suitable plants (not all are good) and then fed it back to the snails.  I know that some macros are grown to feed their fish (ie "Tang Heaven"), so this idea is not off-the-wall.  In the end more plant matter must be removed than recycled into the system.