In my experience you can boil bog wood all day changing the water every 5-10 minutes and you'll still have it darken the water. Eventually it clears up.
My bogwood eventually stopped leaking but took some time. Even though the brown water is overly attractive to look at, your fish prob feel more at home in it and safer.
the bog wood is an essential feeding ground for plecs if you have any. bog wood can be soaked for up to two weeks before all the colour is removed.
i also like the colour it turns the water - in a well stocked, natural live planted tank it gives a very nice effect and the fish generally seem calmer.