Leak around raised spa

[jhnhth]

I have a leak in the stonework around a raised spa with a water feature that runs into the pool below. There are signs of efflorescence and there is water leaking through the stonework on both sides of the waterfall. It appears to be coming through the grout. I guess it's the minerals leaching through the wall that caused the leak. What is the remedy? Is there a way to patch or seal the grout on the exterior walls? Or do I need to attack this problem from the spa? Thanks in advance for your help!

I tried to attach a photo but get an error message that it's not possible to determine the dimensions of the image, it's posted here https://i.ibb.co/JtZf3V9/IMG-0215.png