Sandbox :

Where were the soil samples taken ? Here are 2 articles on lime in ponds. Acid soils and water will stop many plants from growing (like plankton) but many others like acid soils. It is difficult to get and sustain a plankton bloom with an alkalinity below 20. Adding lime will help even if you do not plan to fertilize. In fact I would suggest that before you think about fertilizing you get the alkalinity above 20 (higher would be better say 40) and see what happens. You may get a good bloom with out adding any extra nutrients. Soil samples of the pond bottom would tell you a lot.

http://www.mdsg.umd.edu/Extension/finfish/FF7.html

http://edis.ifas.ufl.edu/FA028