Microcystis aeruginosa biovolume

[Mikey =]

   Does anyone have a lab procedure for calculating biovolume of
Microcystis aeruginosa?  Using lake water samples, I need to accurately
obtain the average biovolume/liter from approx 60 samples. I am currently
using a Sedgewick Rafter and after calculating the avg # of colonies/ml,
ave # cells/colony, and avg dimeter of cells extrapolating up to the
biovolume/liter.  This, however is extremely time consuming, and I was
wondering if anyone has found a simpler method.
   Thanks in advance
   Michael R Attan
   Oakland University Dept of Biology