Question about mold/fungus eradication and prevention

[Paschale]

So as always, I'm working on a project that I should have worked on this summer.  I'm repairing a pillar on my front porch which had some dry rot that I discovered a couple of months ago when I was stripping it for painting.  I cut the punky portion out, and discovered that over the summer, some fungus had spread up inside the pillar, obviously as a result of the extra moisture getting in because of the dry rot.  I bought some fungus killer, used for decks, and I've been working on the inside.  I'm about to go to Menard's and buy a chimney sweeping brush to really get the cruddy stuff out completely.  I'm thinking of spraying after this a mixture of water and bleach to kill whatever's left over, and finally, spraying the insides with a compound I've found that's used in marine building.  It's nasty stuff--has arsenic in it.  Obviously before I do this, I'm going to make sure it's thoroughly dried out.  Probably by placing a fan on the inside, and letting it air out for about a week, with the occasional space heater, to provide a little bit of heat, though only when I'm here to make sure it doesn't get too hot.

So...a couple of questions:  does my prep work sound like it will work?  Is there a better product out there than standard fungicide for decks?  Do you guys like the idea of putting this marine wood protector on the inside? 

I don't want to have to replace this thing two years down the road.  The wood inside is thankfully still sound--this fungus showed up just this summer, and it hasn't penetrated the wood yet.  I think it was on it's way to becoming spalted!   ;D  These pillars are beautiful:  Douglas fir from 1928.  I don't want to lose them.  My neighbor just replaced his with some fiberglass ones, and they're ugly. 

Any thoughts?

Thanks!

Dan

[beenthere]

Sounds like there is moisture getting in somewhere. That would be problem #1 to solve.
Is there a chance to do that, or do you think your repairs have fixed future moisture problems?

Is the pillar in place, or are you working on it removed?

What is the marine compound that you can get that has arsenic in it?

Dan
Having a hard time piecing the story together. Prolly me.

You say you have fungus, removing dry rot, cut punky portion out, sweeping out the cruddy stuff, wood is still sound.
These things don't seem to add up.  : :