Need help with an old tank

[LoneStar45]

I am getting back into the hobby after a 12 year hiatus.
I have a Oceanic 150 gallon (rimmed) tank that has been sitting in a shed for 12 years. I cleaned the tank up as well as I could but there are stains on or in the glass that I cant get out (It looks like calcium or hard water stains). I've used acetone, barkeepers friend, and CLR). Its as if the stains have leeched into the glass itself. I was told once water was in it that they wouldn't be noticeable. The tank has been up and cycling for about twop weeks with no lights, and it looked pretty good until.... I decided to take an LED shop light and shine it into the tank. The stains are extremely visible and with 3.000.00 in plumbing, equipment, etc, will be forced to toss it all to the curb and start over unless someone can offer a miracle solution. I also spent another 600.00 getting the stand refinished and reinforced. The tank is 72x18x30 which I believe they don't even make any longer and Oceanic is out of business. My only option that I see at this point is spending another 3 grand on a new tank.
Any help would be appreciated.

 

[Sk8r]

White vinegar. Hang a towel over the problem spot(s) and pour straight white vinegar over it. Keep doing that. Vinegar (an acid) dissolves calcium carbonate ---may take a while if it's gotten into the pores and micro-dings of the surface, but it will get it. There are stronger acids which can be dangerous, but white vinegar usually does it. You say glass. If it IS glass, it will take to this pretty fast. There is a remote chance the glass has actually been etched, but I doubt it. Usually it's plain old calcium.

And quite often any residual shadow of it goes away (visually) once the tank is filled. My advice is go ahead after treatment, set up, and if you ultimately decide you want to stay in the hobby and must have a new pristine tank, that's a half a week of spare time (and a lotta buckets and Brute cans) but it can be done. I had to shift a 100 gallon bowfront with massive oak stand and canopy to install a new floor and it was a few hours' work to drain, break down the reef into buckets and reassemble. I'm confident you could do a whole-tank transfer and shift about (on Teflon glides) with one helper and a few hours.

 

[LoneStar45]

Thanks for your reply.
When It was empty, I did try vinegar first and it didn't do much however I didn't let it soak. I just wiped it down with a little scrubbing. and went to something else (CLR) after that didn't do much, then Barkeepers friend after that and figured that's as good as it gets and the water would hide it. Not the case obviously. I didn't know glass could corrode but that takes quite a while and maybe it has but to that degree? in any case, I will have to drain it all and remove the sand, and rock and flush it several times to see if it helps. I'm so far into it money wise, already, I might as well have another tank beside it to transfer to....