Surveyor1951

I installed a new pump on my Softtub. I installed one of those blue plastic hydro heaters that clips to the pump. My original pump had the steel heater coil that goes around the whole pump. My circuit board worked fine before I installed the new pump. My new pump is the same model as my original one. My soft tub now runs for half hour & heats up for for about half hour the shuts down for about half hour then starts up again. While it is shut down for the half hour the jets will not run. I have the softtub set at 100 but the water temp is only 94. I installed the pump 2 weeks ago. Any ideas what the problem may be. Any ideas would be much appreciated. Thanks