Ok, Roak asked me to expand, but I think FREDT summed it up pretty well.
The issue of filling tanks in water is a sticky one. Some people/agencies believe that you should never fill in water, because it has minimal benefit, and it forces water into the cylinder.
They may be right, however, what we have found is that if you do not drop the whip or the tank valve below the surface of the water, there is NO chance of water going into the cylinders.
The way we have our tub set up, the tanks slide in, and just lean against the side, so the whole tank is NOT submerged. just the bottom half or so of it. The whips NEVER get wet, nor are they ever SUBMERGED.
Steel tanks heat up during a fill. Alot more than aluminum, which tends to dissipate the heat much better than steel. Steel tanks need to be filled slower, and cooled off in a water tub in order to ensure a good fill.
I stated earlier a 600 psi per minute fill. That is kinda fast, and I think steels we do more like 300 psi per minute.
Also, service pressure is measured at 70 deg f. I left that part out, thanks for that FREDT.
We actually never have a problem giving good fills because of the slow fill rate and out water tub. People actually thank us on a regular basis for the good fills...
I think people are used to getting shorted a couple hundred pounds on a fill. You really need to be patient, and let it take more time, and you will get a good fill.
I also fill all my own tanks, so I never have a problem with getting a good fill, unless I am in a rush to get to the pool, and then my tanks get a short fill. But, in a pool, its no big deal. I like a real FULL fill for all open water dives however. I dont like getting my tanks filled somewhere else...
Roak, did that help???