Personally... I like the chicken bone thing and dancing. Make sure you have someone take pictures so we can all know how to do it ourselves.
But seriously, I use Reef Crystals with DI
water and have never had any detectable phosphates using the Salifert test kit. So... I don't think your salt mix is the problem.
I'm thinking your water district is primarily using well water and you're not running it through an RO
? Just guessing, but maybe with the increased rains now that we're knee deep into fall, you're seeing increased runoff from fields and roads that may boost up the phosphate levels? You might try another person at the water district, as I thought phosphates were something they had to test per Federal requirements. Maybe Melosu can chime in on that.
When I first started my tank, and did have some phosphates (from the "previously frozen" cocktail shrimp, I'm sure), I got rid of them using RowaPhos pads and they worked great. Not sure what all you've tried already, but if you haven't tried the Rowa product yet, you might give it a go. Pricey little buggers, but they seem to work well, and fast.
And don't forget the pictures of the chicken dance.