got a 350l wydale tank. has large outlet not sure what size they are. http://www.purefreedom.co.uk/water-tanks/fittings/large-tank-outlet-fittings-kit.html anyways it leaks where the plastic fitting is. and for the life of me cannot stop this small leak. tried taking it out and redoing the ptfe tape etc and nothing stops this leak. starting to think these plastic fittings are not upto the job. are there metal/brass types instead guys? what size is the plastic fitting?