Very nicely done!
The only part I question is choking the FX5 down to 5/8" tubing to go through the heater. This seems like a waste of the cleaning power of the FX5.
You might consider building a bypass of 1" pipe/hose around the heater but still keeping the heater in a straight line with the pipe. This way the water will want to continue in a straight path through the heater but the water that is choked by the 5/8" orifice will be routed through 2 X 1" T's and 2 x 1" 90 degree elbows around the heater. Should provide plenty of circulation through the heater while not crippling the flow of the FX5.
Your cherry is very beautiful... and it will get prettier as it ages!