What do I do with dry fertilizers?


Lifetime Charter Member
Lifetime Member
Mar 12, 2009
Tom has his own density measurements that he uses; they are not the same as Fertilator. I have to use Fertilator when helping you because I use a scale, and don't know the densities. From my calculations and Fertilator, using the low end of Tom's method, you'd be dosing:

With a 65L column:

NO3: 24.53ppm
PO4: 7.52ppm
K: 24.08ppm
Ca: 0.27ppm
Mg: 0.09ppm - didn't account for how much CSM+B will add, but that's negligible.
Fe: 0.78ppm

Seems like a lot of PO4 to me, but it's probably nowhere near toxic levels. At worst dose 1/2-1/4 the KH2PO4 and see what happens.

Tom, what level of PO4 are you dosing on a mid to high light tank these days? I've been aiming around 1.5ppm per week based on my past readings, and figuring in for a 1-2 ppm added through feeding. Semi-accurate test kit says 3-5ppm.



Lifetime Charter Member
Lifetime Member
Jan 5, 2009
Washington, DC
I feel like I just had a tooth pulled

Sorry Philosophs, I didn't realize Fertilator listed CSM+B.
I think tom said 3:1-4:1 by weight KNO3:KH2PO4 (PO4 at 4-5ppm). So I can adjust that accordingly.
Top of the day to you all.