Hose adaptor for Overflow tank connector...

[Chud]

Bit of an odd question but relates to plumbing fittings so I'm guessing this is the right forum...

I need to connect a hose (e.g. washing machine outlet hose) to the back (i.e. threaded end) of an overflow tank connector like the one in this link.

http://www.toolstation.com/messages.html?code=45586&mainWin=1

I know a hoselock 3/4" tap connector will screw on to the end of this but there are 2 problems with this:

1) I do not want to use a hoselock female connector as they tend to drip a bit (this will be indoors)
2) the bore inside the hoselock connector is too small - ideally I want to use something with an internal diameter of c. <19mm

Can anyone suggest a suitable fitting that will give a good seal and allow the connection of flexible hose?

This is for an overflow from my main aquarium into the sum tank in the cabinet below.

 

[wiggikins]

Don't your local tropical fish suppliers/outlet do anything

 

[Chud]

Not that I can find!

I'm really beginning to hate hoselock as all you can get in the way of tap connectors now is their type fitting - not the old style push on fitting that you put a jubilee clip around.

The other issue I have is that it's got to be plastic as it's for a marine tank.