Help on setting initial dosage, new aquarium.

Hi,

Planning on making my own npk for a planted 60 gallon aquarium.
Will also use co2

I intend to use 500 ml solutions.
And dose 20ml once a week.

Using tap water, no need for calcium or magnesium and seachem flourish for micro.

Can any one check my calculations?




From the numbers it supposed to last half a year.
Am I right?
Is it ok to keep solutions that long?



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