OK - turn my filter off (TetraTec EX600) to clean it. Put it all back together, connect pipes etc and start to prime filter. Jaqno fills with air from the empty filter and at this stage water is no longer pumped into the filter, not entirely sure why. With the Jaqno full of air it is then impossible to get any flow through the filter and even if I could there is no easy way of refilling the Jaqno with water without unscrewing the lid and submersing the thing in water before putting the lid back on. Am I missing something obvious here? The gas release valve seems pointless too, there is no pressure in the thing when running (logical really) so the gas release valve can't release anything even if gas did build up.... Hmmm.