Advice on Outdoor Stains?

I've stained a porch swing using Thompson's WaterSeal Tinted Wood Protector. (Walmart..1 gal can). The swing is made of standard Southern Yellow Pine...not pressure treated. It mildewed..looks like within the stain itself. I completely sanded the swing, and re-stained from scratch with the same product, following all instructions for drying time, etc...same results.
What would you advise on staining and weatherproofing plain 'ol pine for outdoor use? Thompson's states on their can that it is UV protected, beads and waterproofs, and resists mildew. It beads... but it does mildew. Thanks for your time Dale
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Kill and remove the existing mildew using a cleaning solution (1/2 c TSP, 3/4 c. household bleach, 1 gallon warm water) in a garden sprayer. Scrub and rinse well. You may need to repeat if there is still some remaining mildew.
I use Cabots decking stain. It has mildewcide, but add a packet of mildewcide in addition. Apply when your porch is absolutely dry. This should last a few years. Forget about Thompsons.
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