Yet another example of "Less is More" with Feeding

[Ray]

First, I want to apologize for not responding. I somehow missed Paphlover's post.

Most fertilizers are inorganic salts, so extremely chemically stable. When I make up a batch of concentrate for my greenhouse, it lasts several months.

Yes, the chemistry in the S/H pot changes petty rapidly, but due to nutrient extraction by the plant, but also by it dumping its wastes and by evaporation of the water. Flood the plant frequently with a very dilute fertilizer solution, and it completely resets it back to your intended chemistry.

Concerning algae growth - eliminate the light, and you eliminate the opportunity for algae to grow in the concentrate. You may get a bacterial "bloom" on the surface, but best I can tell, it has very little impact, other than requiring you to clean the tank before the next batch.

[Ray]

Back to PaphLover's post a moment, while fertilizers and some additives are stable, rooting hormones and biological additives are not, so should not be added to "stock solution" tanks.

I got around that by using a hose-end sprayer to apply them monthly.