Losing water. New pool owner

[Tiger1982]

I'm a pool rookie. Never had one before and bought house with salt water pool.

Anyway, it seems like my pool is losing water. It's concrete. I don't think there's a leak, I guess it's possible but I think it's something I have wrong.
I have figured out how to vacuum the pool. Cut main drain off and leave skimmer on.
Now under normal everyday settings am I suppose to have main drain and skimmer open all the way? That's what I have it on now and seems like water keeps dropping. There's water in the skimmer but I know it should be higher.

I have a lot to learn so I'll be looking around the forum but this is my first concern.

 

[mrcarcrazy]

Bucket test.

get a 5 gal bucket and set it on a step. Match the water level in the pool with the water in the bucket. (the top of the bucket needs to be above the water level) See if they drop at the same rate.