You need to get some bleach in that pool now. The SWG won't be able to clear algae, even when it is working.
First thing to check: Is it actually producing? There's no error lights, right? And it's bubbling inside the cell? If so, push a cup upisde down into the pool, then turn it up right in front of the return flow so you capture the water straight out of the SWG. Test that. It needs to be tested right then, not after an hour's drive to the pool store. If it shows chlorine, then it's working, it just can't keep up with the demand. You need to get ahead of the algae and then it can resume it's daily job.