# OSMOCOTE® calculation

```Hello folks,

I've just received a bunch of TROPICAL OSMOCOTE from ScottŪ, it's a slow
release fertilizer particularly low in P. Composition is as follow:
------------------
TOTAL NITROGEN (N)

18.00%

8.50%  nitrate nitrogen (NO3)
9.50%  ammonium nitrogen (NH4)

ANHYDROUS PHOSPHORIC ACID (P2O5)

soluble in neutral ammoniumcitrate and water-soluble
1.60%

water-soluble
2.20%

POTASSIUM OXIDE (K2O)

water-soluble
9.30%

Longevity: 12-14 months at 26C
--------------

now I'd like to you to help me in determining the exact dosage to put under
the substrate on my new tank that I'm going to set up soon:

the tank measuares are: 45*30*27(H) cm for a total of ~36Liters, let's say
around 30L of net water. Now considering an average of soluble P (and
considering it as the limiting nutrient!) as 2% ... if I use 20g of
OSMOCOTE, I should have 0,4g of total P. That's 400mg. Let's say that they
last 400 days (12-14months at 26C). 1mg of P for each day. That's lead to
the following concentration of 1mg/30L -> 0.03ppm P which should be uptake
_every_ day from plants; possibly from plants roots for not going into
water column.

what do you think? any suggestions? am I wrong?

ciao!
Luca

```