EI dosing


Prolific Poster
Jan 21, 2007
In reference to my previous posting all the ferts. will be way above the recommended levels even with a 50% weekly water change assuming no nutrient uptake being the most extreme. eg in a 120g tank the recommeded dosage for NO3 as KNO3 is 1.5 teaspoons three times weekly. This gives a measurement of 31.59ppm of NO3 at the end of the week prior to a water change-using FERTILATOR.

With 50% weekly water changes the max that NO3 can reach is DOUBLE the original dose ie. 62ppm, and that is assuming no nitrate uptake by plants and no endogenous accumulation of NO3 from bacterial oxidation.

So are the recommended quantities of ferts correct? If so please enlighten me>

Tom Barr

Staff member
Jan 23, 2005
Well, that's a bit rich, not much, but still a bit rich.

Try 1 tsp 3x a week max.
Add some fish in there and you have more than enough NO3 and K+.

That targets 20-30ppm a bit better which is an ideal range.

20-40ppm for K+, and 20-30ppm for NO3.
You are not adding all the KNO3 in at once either, so those upper ranges, 40-60ppm will not be reached till the last dose before the water change.

Can you use less and do 1 tsp, yes, if you have less light, there is no need to add that much also. Say 3/4tsp if you have good fish load and 2w gal or under.

Tom Barr