Help! Is anyone familiar with these units. Are they any good? Can they handle the work load required by my pool?

Here's the scoop!
17x33 Inground (vinyl) approx 17000gal
Pentair 2 speed whisperflo pump (.25/1.5)
DE filter
Electric Heat pump
Pool is in it's 3rd season

1st unit I had was installed wrong by a "professional" and did not work. Received a 2nd unit and have noticed that it only seems to generate when pump is on low speed. I've never run pump just on low before. Can I? Will it be beneficial or will it drastically hurt the circulation and filtering capabilites? Since it's been installed it seems to be holding the chlorine levels previously established. However, to really test the unit, I've had the generation knob set to high and have even superchlorinated 2 times to see if the chlorine level would increase. It has not increased at all. Is this normal? The remainder of my pool chemistry is near perfect (CYA a tad bit high). Sorry for jumping around, but hopefully this gives enough information for someone to help me out with some answers. I am beginning to wonder if perhaps I wasted money on this brand and should consider something else. Thanks!

Welcome to TFP!

With a two speed pump used on low you need to run the pump for twice as long as you would run it on high. Twice as long on low will use just over half as much electricity and will filter the water slightly better. For most things low speed is better. However, low speed might not be sufficent for vacuming or pressure/suction side cleaners, or for priming a solar system, depending on your exact setup.

How much chlorine the unit can generate is constrained by your pump run time. If you are running your pump for only a couple of hours a day your results would not surprise me. You also need an appropriate salt level, typically around 3000 ppm. Most SWG work best with CYA between 50 and 90, though you should check your manual to see what they recommend.