What is the nitrogen content of a "cube"?

[BIO-Linist]

What is the nitrogen content of a "cube"? (I know it has P and other stuff in it but I'm only interested in N right now for some rough calculation)

Background:
Recently setup a 125 US gal. freshwater (with sump total volume is about 140 gallons).
From testing NO3- before and after changing water I came out with about 2 grams of N per week exported via water changes.

Thanks

[SantaMonica]

Depends on the food of course. In the past, I've calculated that an average 3 gram cube of food has 0.3 grams of carbon. But for nitrogen, here is a chart that might help...
http://www.scielo.org.ar/pdf/aaqa/v9...v92n4-6a11.pdf

Table 1 shows that wet meats (probably mostly what are in cubes) are about 3 percent nitrogen; so a 3 gram cube would be 0.09 grams nitrogen.

[BIO-Linist]

Thanks!

Now to figure out the energy cost to remove 3 cubes/day...

EDIT:

12W x 18h / cube = 216Wh/cube

216Wh/cube x 3 cube/day x 0.001kWh/Wh X 30days/month = 19.44kWh/month

19.44KWh/month x $0.36/kWh = $7.00/month


EDIT2:
Would anyone happen to know the average mass of a Hikari Algae Wafer?