Re: What would cause a small pond with no inlet or outlet to clear overnight?

Ray,

There are a couple of things that may be happening in your pond.  The first
thing to find out is whether the murkiness is due to suspended solids or
algae.

It is more likely to be due to algae if there is no relation to weather.
For suspended solids to settle out, a period of calm is required, and
similarly a method of mixing is required to keep suspended solids in the
water column.  Keep in mind that for very fine sediments, this mixing may
be caused by very slight wind over the surface.

This phenomenon may be better explained by algal ecology.  These micro-
scopic organisms often display a "boom or bust" growth pattern.  That is,
they grow until they exhaust available nutrients.  Then the population may
suddenly crash and sink out of the water column.  After a few days, the
decay of the algae will release nutrients and the cycle will start over
again.