RO water reconstitution

[Epiphile]

Hi everyone,

I'm fairly new to all of this, and have a poor understanding of the science involved, so I'm hoping someone can help.

I'm currently using RO reconstituted with MSU fertilizer for pure water. What I'm wondering is whether there's a minimum level of fertilizer I can use, above which I won't see nutrient deficiencies. I realize that different species prefer different nutrient levels, etc. I'm hesitant to shoot for levels optimal for plant growth because some of my plant are kept in vivaria into which I'm hoping to introduce amphibians, and am seeking to find some manner of middle ground between the two. At the moment I'm dosing to a meager 10-20ppm N, and I wonder whether I'm asking for trouble.

Thanks in advance for your thoughts.

Aaron