After reviewing the imaging test it turns out that I failed to lock the Moonlight focuser during the test, thus it shifted out of focus under the weight of the rig. After reassessing, I have decided to go to a lighter water block ( the Raystorm GPU one was heavy copper plate), and purchased a cheap aluminium one from ebay.
http://www.dx.com/p/aluminum-water-b...0#.VwOYI1Jrm-c
I will stick a 40x40mm thin copper plate between the TEC and the aluminium block to improve the heat transfer off the TEC.
The aluminium block takes a smaller ID hose as well. After discussing fluid dynamics with my son (the engineer), I have decided to keep the present pump/radiator system and use a 'fluid bridge' and reducer to feed the new block. I will go to thin wall aquarium silicon tubing for the feeds to and from the water block, with the larger hoses retained to the bridge, radiator and pump. Pressure will increase in the line feeding the water block but volume is decreased. Just sourcing the reducer fittings and bridge now. The bridge will be mounted on the pier and the new thin lines will run from there to the scope. More testing to come, stay tuned.