If you have a small amount of water that is collecting in the tub/base and not running out of the waste this is because the tub has not been correctly set up and tested in place.

The base MUST be tested when it is initially put into what will be its final position.

Ensure that the water is able to run completley to the waste.

If the base appears to have a shallow dip in it at any place, then adjust the feet under the tub to raise the middle a little.