I'm currently paddling on coastal plain blackwater rivers, fresh to brackish water. Mostly "fresh"... though, I would not want to drink it..

I think if I were on the sea, I'd probably flood the kayak with saltwater a few times in the first months. I think the wood you find on the ocean floor has likely been in the water so long it is purely waterlogged, that's why it sinks. I don't think that's going to happen to your kayak frame unless you leave it tied floating to the dock for about 20 years after the skin rots off. But use in saltwater is supposed to pickle the wood, so I've heard.

That's a lot of "I think" and not much "I know", I know.

Paul and Mike's suggestions for mildewcides sound good. I am thinking of trying the borax thing, or something, but truthfully I'm probably too lazy to do it. The most mine will likely get is a pool session here and there, but not so much in the summer. The only bother I've had with mildew is when it shows through the skin in ugly blotches. It doesn't seem to bother me from an allergy perspective. And I do tend to see these SOF as disposable, especially now, in the learning/testing stage of my addiction.

It did dawn on me the other day though that probably these really low volume "flat" SOFs have a much harder time drying out due to even less opportunity for air circulation. Another "I think"... maybe I need to move the rack more to a sunny spot. I live in the woods basically, very humid and damp everywhere, surprised they don't rot in one summer, actually so I guess it's not too bad.