Swap the supplied bulk-heads with some from a hardwear store. Look for some using a Vynal seal ring as they last better than the silicone ones. The seal ring goes on the outside, and shure it up with silicone inside (apply round the hole and screw the nut on-to the fitting nice and tight, before smoothing round with you damp finger)
TBH, there is more risk of the filter itself leaking if it is the standord Fluval exturnal. Their Aquastops and main seal's are notorious. I'd replace this filter personally. If you are using a new set of bulk-heads, the Fluval will need to be converted to "normal" smooth flexible pipe, with the hose secured with a jubilee clip on each end of the hose.
To drain the pipes without first draining the tank, push ridged PVC pipe into the bulk-heads in the tank before opening the valves to drain the hose. With the inlet and outlet effectively lifted out of the tank (the PVC should reach above the surface), the PVC will allow the pipes to drain without pulling more water out of the tank. You can then push the pipe-cleaner through without spewing water everywhere
To prime, re-attach your filter, open the valves and then take the pipe over the inlet side off (not the outlet side yet) and wait for the outlet pipe to fill with water through the primed filter. Then remove the outlet pipe and switch on the filter again.
HTH
Rabbut