First, educate your marina!
I know...easier said than done, and it doesn't solve your problem.To answer your last question first...emptying the holding tank through the Lectra/San doesn't work--for a couple of reasons: In order to kill enough bacteria, each flush must be treated multiple times before being forced overboard (which is why it's absolutely essential to run it with every flush) and just letting it run while the tank empties doesn't treat it sufficiently. Plus, there's no pump in the Lectra/San...just a macerator...the device literally overflows as new incoming forces treated waste out through a discharge fitting on the top of it (another reason why it must be run every time the head is flushed...if you don't, you're just sending untreated waste overboard). So the Lectra/San can't handle the volume from a tank for both reasons. Nor can the Lectra/San go into the tank and make it legal to dump the tank. It reduces the bacteria count to between 50-200, but that still leaves enough of the buggers alive to multiply beyond legal limits (and stink). So I hate to be the one to break it to you, but the only practical way to install a Lectra/San and a holding tank is to put a y-valve in the toilet discharge line which allows you to choose between sending the bowl contents to the Lectra/San or to the tank. Trying to use both in any kind of tandem doesn't work. Btw...if we can be of assistance in supplying the tank, I'd love to. You can either call me at 770-512-0075 or e-mail me at peghall@bellsouth.net