Mike I do not feel you can calaculte on just the Po4. Base it what works per acre. I think 4-8 lbs/acre of good high phos. water soluble fertilizer works as does 2 gals/acre liquid. So I compare the 6 lbs to 2 gals. ANother way would be to compare the 4lbs to the 1 gal this minimum rec. for each. This would mean $4.14 ws vs. $7.64 liquid per application. This is a great price on the water soulble btw. All ponds are diff. and some might work better with liquid others granular other water soluble. The liquid to me works very well but only when diulted 5 to 1 then slowly added to prop wash. I do not doubt anyone will argue which is easier to apply 4lbs of water soluble you can throw out or 1 gal (10 lbs.) you have to dilute ,etc. Can you tell which one I like and invest in? \:\)

Greg Grimes
www.lakework.com