Cleaning a SW tank for FW use

I used vinegar , hot water & med sized sponge, and carefully scraped the hard water stained surfaces with single edge razor. it took about 1hr for my 90gal and it came out very well.
 
You're welcome, I would be careful that you not use to hot a water temp. I would not want it to crack. a little warmer than hotter would be my suggestion.
 
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