It may not be a fertility problem but a water turnover problem.

I assume that your fert. program worked before and no change in the water condition (alka. etc) has occurred. In other words the only change from when it worked to now is the aeration.

If so a possibility may be -- if pond is turning over at a high rate due to aeration you may be sending the plankton to the bottom (out of the sunlight) to much to keep a good bloom. It can die (individual warmwater plankton) when it is subjected to no light and cold anaerobic conditions at the bottom.