I just received my Scott Koplin STAs... One light, one 6 pounds heavy. I'm so pumped.
I'm going diving all day tomorrow in a new spot. Someone's tounge slipped, and I found out where our local "big shark tooth hunter" is finding all of his $2500 megawhoppers. (Bigger than your hand.)
So tomorrow, bright and early I will be diving (zero vis) on said spot. Here's the killer... I can reach the spot in my little jonboat in about 1/2 hour. I had no idea it was so close! Maybe I can make a little money tomorrow and buy some more cool gear.

I'm thinkin' I need a bigass boat for diving these wrecks out here.
Anyway, I'm really pumped about my STAs. Thus far, I've only been diving the integrated STA that comes in the Halcyon Pioneer 27 wing. It's been nice, but then when I dive my local salt waters, I need another six pounds with the AL80's that I use (I dive wet). Thus, I've been carrying a 3 pound weight on either side of my belt for perfect buoyancy.
I can't wait to see what this 6 pound STA does for my trim. I'll give a full report tomorrow.
I've just installed it, and I won't be diving with those 3 pounder weights tomorrow.
If this works from a trim perspective, then I'm going to consider permenantly installing the Koplin 1 pound "light" STA, and simply diving an AL80 in freshwater and a PST E100 in salt. It's looking like that might dial me in perfectly, and I'll never have to deal with weights again.
Here's the clincher... If this works, then when I dive salt water (which is most of the time) then I'll be diving a tank that holds more gas, is 2" shorter than what I've been using, and my overall rig will be 5.3 pounds
lighter on the boat or dock than an AL80 with a 6 pound STA! Smaller, lighter, and more gas... I like that! Here's the clincher... It'll be smaller, lighter, and have more gas
even if we were comparing a PST E100 with an AL80 at the same fill pressure!
Too bad I can't be this tricky in freshwater too. In order to do this safely, I'd have to dive with an AL backplate, and then I think that would throw my trim off pretty badly... With me ending up "turtled" easily. I dunno... I'll do some more research and get back to y'all on that.
Hey... Another lightbulb just went off... This is why DIR advocates "no steel tanks when diving wet," isn't it? Duh! God, they're good. 'Course, I know that my math works for a steel tank in salt, just not in fresh... I think they'd approve if they saw my math on this one. No matter... I know it's safe.
Anyway, then all I'll have to do is retrofit my regs and the AL80's to DIN, and perfect buoyancy and trim will be the world of simplicity. God, I'm gonna be like a bat underwater.
The only issue that I'm worried about is the idea that it's possible that going with a PST E100 in salt might bring my CoG back too far... Creating a "turtling" effect, even in salt water. That would suck. I think I'll have a good idea if that's going to happen based on tomorrow's dive with the heavy STA.
My gosh, it gets even better.

Try that with your off-the-shelf jacket. Sorry, you're going to always be stuck with weights...