all those views and not one reply till now - come on guys help the man out!!
to flush a merlin without a flushing kit you need to force feed water (preferably pure water) through the top elbow on the manifold, this will flush water over the membranes and out through the drain. The easiest way to do this is to connect your garden hose to the manifold or to use 3 inches of plastic pipe and connect it into your microbore (if you use it) and then into the manifold, then pump pure water through the merlin. Its a little tricky to do but worth doing, but always better to do with pure water.