Reddit mentions of Yellowstone Fly Goods Fly Agra Floatant

As with most things fly fishing-related, it depends upon the speed and depth of the water you're fishing. But as a general rule, I fish an emerger pattern (like a Barr's Emerger) 12-18 inches behind my dry fly and am essentially using the dry fly as an indicator for my emerger. If I'm fishing something that is beaded like a pheasant tail or prince nymph, I've fished anywhere from 12 inches to 36 inches based on the speed / depth of the water and the size of the fly. Generally the deeper the water, the longer you'll want that tippet to be. Keep in mind too that you'll have to downsize your nymph based on the size of your dry fly. Something like a size 16 adams can really only support a size 20-22-24 beaded nymph and still maintain it's surface. Also make sure you use dry floatant on your dry fly (I'm a huge face of this stuff).

I don't recommend trying to fish both the dry AND the bottom of the water (unless the water is less than 3 feet deep), since to me you're just doing both a disservice. If I'm fishing a dry dropper, I'm usually targeting the surface and just under the surface (6-12 inches or so). Sounds like you're already an expert in fishing subsurface nymphing and getting it to the bottom.

Hope this helps. Tight lines!