Just remember, the super minus low tides ("king tides") that occur each year, don't in-&-of-themselves bode for good detecting. If the wet sand is "sterile", then the only thing those monster low tides do, is give you tons more room to walk around in, and find nothing ! So there should be some erosion going on (swells, on-shore winds, etc...), to complement the super minus tides. Otherwise super minus tides don't mean much, IMHO.