Have any one had a problem with the GFO not tumbling at all , when I install the the 1st reactor with carbon it work fine , I just purchase both of them , with 2 new MJ1200 pumps , I also to it apart ( twice ) and all the parts was ok , the GFO granules I'm using is from BRS , I made sure I didnt put to much in , its only 6in. , the instruction says No more than 8in. ? any thoughts what I can do