organism size based on pulse strength, with strong pulses attributed to large organisms and 
weak pulses attributed to small organisms, whereas the microscopists used photomicrographs 
of 50 pm calibration beads (> 50 size class) and Sedgewick-Raftergrid widths (10-50 size class) 
as size references. Inaccuracy by either method may lead to discrepancies in counts across both 
size classes, thus, it may be beneficial to examine the accuracy of size measurements for future 
comparisons of analytic methods. Further, discrepancies can arise due to human error, 
particularly when conducting microscopy (First & Drake, 2012) (though not limited to 
microscopy) due to inability to detect FDA 'staining' against background autofluorescence, 
fatigue, motion sickness, etc. Notably, Satake Pulse Counter and SGS ATP (aqua-tools) had 
similar outlier data points for the same sample, where measurements were quite high 
compared to microscope counts, which may indicate error by microscopy or poor mixing during 
the sample splitting process. 
While this paper has compared the accuracy and precision of different analytic 
methods, factors such as cost, training requirements, and the time required to analyze and 
process a sample are also important considerations. Microscopy is the most demanding 
method, with requisite taxonomy skills, 20-60 minutes processing time per sample, and a 
substantial investment in equipment, making it an unlikely choice for compliance monitoring by 
non-scientific regulatory personnel. For the handheld CFA devices, including the bbe lOcells, TD 
BallastCheck-2™ and Hach BW680, sample processing takes approximately 2 minutes and 
requires only minimal training; the devices range between $3,700-$4,800 and running costs are 
< $1 per sample (all values are approximate and in USD). The desktop Walz WATER-PAM, is a 
high-end scientific instrument, and has similar speed, per sample costs, and training