Dosing Calculations


Guru Class Expert
Mar 14, 2006
Toronto Ontario (Canada?)
OK, I hate doing things I don't understand, so here goes -- I am just getting into this EI thing -- I read the paper on it through a number of times.

So I start calculating -- lets take Phosphates as an example.
I want 3ppm. I have a 60g tank (65 nominal). Using Chuck's Calculator, I get
1/5tsp approximately. Now if I add 1/5tsp and there are 0 to start with, I should have 3ppm. I don't think I am wrong so far.

However, I am going to change 50% water each week. If I want to max out at 3ppm (lets ignore uptake for the moment), I would does 1/2 of the 1/5tsp and
the graph should be asymtotic to 3ppm.

To complicate, I want to dose 3 times throughout the week, say starting \
right after the water change. I figure this gives me 1/5sp / 2 / 3, so
1/30tsp dosed 3 times a week.

So I look over the forums and under "Algae Control -> Help algae problem"
and I find that for a 50g tank a recommendation of 1/8tsp 3x per week.
This is almost 4x my calculation -- what am I missing -- other than uptake?

Sorry, Enginerring background hate doing something I don't understand,
as much as possible.