Is it better to drain the pool and start from new water or to convert to chlorine using the same cloudy water that is full of clear comfort?!
Good question. Certainly less hassle to drain the pool. HOWEVER, If you have a vinyl lined pool, that won't work....they should not be fully drained. Gunite can be but 19k is a lot of water.

Generally, your best course will probably be to convert. Lots of folks have done it on the forum and there's plenty of good threads to follow. It seems the only converters who get into trouble are those that try to combine pool store advice with the advice on the forum. Depending on the store, you may get good advice and you may get something absurd. The advice here is solid and consistent.