[LazyPup]

The water that you are seeing at the first elbow is most likely the water in the trap under the shower. If so, that water is required to be there.

In order to help you identify your problem we would need a bit more information.

You stated that this is a condo but you did not mention the approximate age of the structure. By knowing the approximate age we may be able to identify problems from vintage plumbing systems as opposed to what is state of the art.

Is this shower a commercially manufactured drop in unit or is it a site built shower pan and wall assembly?

Do you have PVC or ABS plastic drain lines or are they metal pipe?