Well, before everyone scares you... Be sure to wip down all the rims of the tank and remove any and all salt crip and water drips. Thoroughly wipe, take pictures if you have to to remind yourself how it looked. DO NOT stick your arms, hands, or any body parts into the tank for a day or two. Nothing.
Then check rims, seams, and outside of tanks for salt stains and / or water leaks. My Black trim always is full of salt because of the water that drips down my arm and out of my arm pit when I'm cleaning the tank. I splash a little here or there and I have to put towels over all the MP 40 dry sides to ensure nothing runs onto or into them. A day or two later, I see salt creep where I didn't get cleaned up from my cleaning foray.
At the same time I had a friend check my tank while I was out of town. He told me I have a leak. I'm like nope, it's just from me, he said, no seriously, your bulkhead is leaking. I've dried it off and waited an 20 minutes and it was wet again. Not what I wanted to hear while I was out of town. When I got back the next day we drained the tank past the rear bulkhead and redid the bulkhead and resealed it and tightened it up. Monitored with paper towels for a couple hours and nothing got damp or wet. Leak fixed.
Making sure an area is dry and free of salt creep then using paper towel where you think the leak is can also be a good way to see if there's an actual leak or if the paper towel remains dry, it may just be from you and/or equipment in the tank cleaning it.