Esshup, I heard back from Jeff Slipke.
Here is what I asked him: Have you or any of your folks ever undertaken a fertilization program for a sand pit that is dug down into the water table? The ones where the water exchanges every so often from ground water flow?
Here is Dr. Slipke's answer: "I don’t have any personal experience fertilizing such a pond. I have dealt with spring-fed ponds that preclude fertilization due to excessive flushing rates. In those cases, fertilization just stimulates the growth of filamentous algae/macrophytes. In the case of the sand pit, my guess is that it would depend primarily on the water exchange rate. If water exchange is low and the pond stratifies, then the nutrients would likely remain in the photic zone long enough to be utilized by phytoplankton. If the exchange rate is high, then you might just end up feeding the growth of macrophytes."
