Rebuilding deck: Question about wood preservative

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Retired & too busy to go back to work
Sep 24, 2017
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Kawartha Lakes, Ontario
I'm working on rebuilding/replacing the back deck. The old one was pressure treated lumber but after 25 years of weather (south facing) and neglect a large percentage of the 2x4s on the deck were starting to rot and about half of the structure needs to be replaced too. About all I want to re-use is the stairs that I replaced in 2017, the posts and the ledger board bolted to the house.

The posts were originally green pressure treated but have faded & weathered to a light gray. The PT wood sold now is brown (I like the look of it better and I understand that the brown stuff is safer so that's OK) and the stairs are brown so I'd like the posts to at least look similar.

Finally the question: Do I need to buy brown wood preservative to do the posts & ledger board (about 46 sq.ft total) and have the rest sit on the shelf forever or can I use some of the brown end cut preservative I'll have to buy anyway (& have the rest sit on the shelf for years too)?
Or would I be better off to just slap on some of the oil based maple deck stain I already have and call it close enough?

BTW: The original deck was put up by the builder's carpenters when the house was being built and is all nailed construction. I will be using joist hangers and attaching the joists to the posts with lags. The posts were originally set on bricks buried about a foot deep (no 2 the same depth) but a couple of them had settled so before I did the stairs we jacked the deck up 1 post at a time, cut the post off (& added end cut preservative), dug out the holes and filled them with crushed stone (tamped) and set the posts on deck blocks. It hasn't moved since.