OC, I have visions of you needing a snorkel for your 100+ gallon tanks.
HAHA!! My smallest one was 110 gallons. I had 2 that were 220 and one that was over 500. All had sumps, which added 30-50 more gallons to the overall volume.
Whenever I grumble about doing water changes on my freshwater tanks, I just have to remember the reef tank days!
Match temperature first (heater mix barrel).
Aerating the water (pond pump in the mix barrel, to circulate the water).
Mixing in the salt to the new water to get it CLOSE to what I will need.
Dumping out the needed old salt water (which corodes ANYTHING it touches).
Taking readings on each tank for current salinity (it will rise due to water evaporation since last water change).
Figuring out the volume of water I will need to return it to the correct water level (dump out 20%, replace it with 25% or more).
Adjusting the salt again in the new water to match the tank that needs the LEAST salinity to to put that tank's salinity at the level I want it to have (figuring out the volume left vs. the volume I will add)
Doing that prior step again for the next tank with the next lowest salinity need.
Oi....
No sir, doing even a 90% water change on all freshwater tanks is far less work!!!!