Instrument for measuring stability of particles in liquid.

I am interested in building an instrument to measure the rate at which particles in a liquid will sediment to the bottom of the container. My idea is to have a laser pointing through the top of the liquid, which hits a receiver. The particles would stop light passing through meaning only a fraction of the light would be received, but as the particles sediment fewer and fewer particles would disrupt the laser. My question is how would I use Arduino to log this data, could it take readings at regular time intervals, and what pieces of equipment would I need to build it?

It is easy to take readings at certain intervals, but where do you put those readings. You need that too.
Laser pointers or bright LED are good. As a receiver I wouldn't use LDR, they are easy to use but not very reliable or stable in the long run.

I think the Liquids will all be transparent, but some use binding agents that make the liquid opaque. Also I thought the resolution of the receiver might be important, since if the resolution of the receiver is too low it might not pick up the difference in brightness. I would eventually want to put the data into excel or something. The process of sedimentation could take weeks so it would need to be reliable for a long time.

Have you a sample where the sediment has settled. Your system should work with light intensity from fully mixed to that.

I'd arrange for a beam-splitter, so you've got a reference measurement for your source beam.