1. don't crash it hard - de power (let go of bar) before the kite hits the water

2. don't pump up the kite too hard

Definately dont under inflate you kite!! That makes your kite fly like a turd (handling, water re-launch, jellyfishing ect)..

Most kites will have some velcro and elastic loop to put over the dump valve, check you have this or see if you can use a zip tie (make sure you have something to open them with at the end of your session), this will stop it from just popping out if you have a crash, also make sure you've properly pushed the plug in, its easy to forget to check this when your excited to go out for a sesh!

With practice you'll stop slamming the kite down (at least not has hard)..well untill you start going for new tricks then you start all over again

Try a nappy

I have an older Core that does something similar. I moved away from the standard plug to a serrated one. The serrations act like teeth and grip the inlet bladder tightly. Never had it happen again however as the previous posts state it gets easier with experience. I picked a few up at my local kite store.

thanks for the info
I managed to loop the elastic around the Velcro twice that seems to have done the trick
And like you's all keep saying practice and try not to crash too hard
Thanks

Well mr kitebt what a clever sod you are, let's hope you have not spoke to soon