Big Terry Filter Limits?

["Tesla list" <tesla-at-pupman-dot-com>]

Original poster: "by way of Terry Fritz <twftesla-at-qwest-dot-net>" <Mddeming-at-aol-dot-com>

Hi All,
A question to the "pro-philter phreaques":
         My "Big Terry Filter" , built according to specs, works fine at 15/60,
15/120, and 15/180. But now that I'm looking at going to 15/240 & 15/300  I
really don't want to find its limit by the trial and Oh S***! method. What
modifications to the filter would be recommended?

Matt D.