Wanted to update this thread. Finally took my other tanks for hydro. 15 steel, 3 AL. Had 1 119HP, 2 120 HP, 10 100HP (all galvanized) and then the 3 misc. AL.
Found Baltimore Marine Safety LLC (well actually I think he reached out to me here on SB after my failed hydro). He was very knowledgeable about the round out procedure needed on galvanized tanks and was even nice enough to show me around his shop.
Dropped all 18 tanks off last Wed and they were done the next day. All passed with flying colors. He even offered to O2 clean them for a small fee. Was $15/tank and $5 for the clean. Was a very cool setup. You flip the tank upside down and there's a nozzle that can either shoot a soapy solution, hot water, or dry air to prevent flash rust. Very, very clean setup.
If you're in need of someone in the greater Baltimore area reach out to them. He takes care of the hydro's for some of the major shipping companies down by the port. Compared to the last hydro place (AND the local dive shop) that tests (and fails) scuba tanks from "time to time" (as they said), this guy knew all about it and said that's it's very, very rare for a steel tank to fail... it just doesn't happen.
Thanks goodness... finding the right person to hydro tanks was probably the last little piece I needed for my personal little scuba shop (aka, my not so clean as his shop basement).
443-622-4261
Baltimore Marine Safety Marine Fire Protection
baltimoremarinesafety.com