PT wood is so wet or green that you have noticed that you can whack it with a hammer and juices run out, these have to dry out so that the sealers or whatever can penetrate and adhere to the wood. depending on your heat and sun, this will take from three or four weeks to three months or so.
Remember, PT wood does not need sealing unless its for your own beautification. Its ready to go and needs nothing.
After it has dried out, you can use the following products that I have tested and rely upon. CWF-UV from the Flood company and Culprinol from Sherwin William's.
These will make the wood look richer and stay new looking, but the wood will take care of itself.