I'm using a solar pump from solarproject (http://www.solarproject.co.uk/page2.html) like a lot of others on here. I also bought some 12mm silicone tubing and plastic connection nuts from them. I found the plastic nuts a bit fiddly! I don't think they would stand up to too much abuse?
I discovered that a 1/2" qualpex insert will fit into the silicone tube nice and snug so with a 1/2" compression olive and nut I've got a much easier way of making and breaking the connection. Hand tight is usually enough although the nut can get quite hot so a wrench is recommended! I added 1/2" brass nipples to the pump too because I didn't want to damage the plastic threads.
The qualpex inserts also fit a standard garden hose so I'm using these for connecting the water hose to my chiller. They don't leak like the hose connectors (http://www.ebay.co.uk/itm/NEW-Garden-Water-Hose-Pipe-Connector-Accessories-Watering-Gardening-Adapter-/200932052192?pt=UK_Home_Garden_GardenEquipment_HandTools_SM&var=&hash=item2ec87bcce0) I was using.
Word of caution,I was gently moving my counterflow unit which is attached to a solar pump and the threaded nipple on the pump just snapped off. Lucky for me I had bolloxed up ??? an other solar pump so I was able to use the part off its housing. :)
they are no load bearing even though they are glass filled resin and will get stressed under temp. Be careful attaching heavy unsupported copper pipe
They are a sh.t design to be honest and should have better radii on valve stem to disperse the load.
I broke a solar pump ages ago while tightening the connector. Peter, who sells them, very kindly sent me a new housing f.o.c.!
A very decent guy.
I'm very carefull since! Still a great pump for the money.
I bought a pump and a load of silicone tubing and he threw in the connectors, very decent chap, but a lot more expensive than china :(