I've never used vinegar to clean either gravel or sand, just plain water. All I do is put a few inches in the bucket than run cold water in from the outside tap, swish the gravel/sand round, then pour off the water plus debris. Then repeat until the water runs clear, that can take 7 or 8 washings depending on just how much fine stuff needs washing out. I put the washed gravel/sand in another container, and wash some more. Once it's all been done I put it in the tank.
I don't use a hose, just put the bucket under the tap. But I can't think of anything wrong with using a hose provided it is not contaminated with some garden or car cleaning chemical.