VCCA Home Forums TECHNICAL - 1945 AND EARLIER 1937-1945 gas tank muriatic acid

I previously posted about my problems starting and operating my '38, after roughly 2 years of sitting idle in the garage. Advice here was to clean the fuel system.
So, I have removed my gas tank It cannot be original; it is in too good of a condition.
I have put several handfuls of driveway rock (crushed limestone, I think) inside and shaken it all out.
My research dictates a 2nd cleaning, this time with muriatic acid. I have read the posts and all the cautions about safety issues.
So, here we go: there's a plastic tube in the bottom of the tank, running to the port where the fuel line attaches. I removed the brass fitting that held the fuel line, but the plastic tube stayed right where it was. Will the muriatic acid hurt that tube? I intend to dilute the acid, to a 1:10 acid to water solution.

As a followup, I tapped that plastic tube. Turns out, it's metal. So, just chalk up one more mistake on me.
I do wonder how I'll use the Redkote sealer, whether I'll somehow need to plug that tube's bottom end temporarily, so it doesn't get gummed up.

It must be a different tank from the OEM tank on my coupe. My coupe drains straight out the bottom of the tank, no tube. I used Redkote on mine with good results. I bought a gallon so it would spread more evenly. I put the unused volume in a sealed container for any future use.

The tube that "glovebox" is talking about is the dip tube that is on the inside bottom of the tank that connects to the fuel line at the top of the tank that goes to the fuel pump.

That's right. My tank also has a drain plug in the bottom, but that's not the issue. It's the one junkyard dog mentioned. So, is there a risk that the redkote will obstruct that tube opening?