What to clean a used tank with?

I brought a used tank and it has some sort of residue on the back of the glass giving it a somewhat of a hazy appearance.The previous owner does'nt know what it is and you can not see it when the tank has water in it,but I have the tank outside right now and would like to clean it throughly before I bring it in the house.I have tried vinegar and it does'nt seem to do much and that was with alot of elbow grease,Any suggestions?


If it is glass, windex will work fine. Acrylic I'm against using such products on.
Also, alcohol (rubbing) works well when trying to get some things off...see how that works
Just be sure to wash out the tank very well before adding water ;)


I would really watch what you use on the inside . sometimes the ammonia from windex is very very hard to get out , you don't want to take any chances .... IMO i would use straight water with a soft cloth . I had the same thing on my hex tank and it looks fine when filled with water , but very hazy without water ...
It is probably mineral deposit from water/ hard water residue. There is a special lime/ deposit remover just for aquariums, I can't remember the name of it right now. I Used CLR on my 20 gallon and rinsed it super good many, many times. Seems fine so far, but the special aquarium kind would most likely be the better bet.
Hope this helps.
Thank you for all the reply's,I tried the CLR and itdid'nt get it off either.When it is filled with water you can't hardly notice it,plus it is on the back glass.