Help....

[Hlie]

It's no use... I used citric acid and lastly I even tried muriatic acid. Non of them worked... I guess the glass is chemically etched....

Well, lesson learned - shouldn't buy used aquarium....

Thanks for all your help guys.

[linarite]

Limestone is made up of calcium carbonate. You could use vinegar on this. It might take a little while but if you keep applying it the build up with be dissolved. If you can find some pickling vinegar which is a little stronger than the standard white stuff it will work faster. The up side to vinegar is that it rinses away completely and won't contaminate the tank.

[linarite]

Sorry, I was typing while you were posting the last note. If you have tried those acids and still have a problem, then, yes the tank is etched. Calcium buildup will not stand up to either of those acids. Maybe you could turn it into a terrarium instead?

[Hlie]

Hm.. I think I'll make it into a river tank
I guess I'll have to make the manifold for 55 gallon this time....

Thanks y'all for the help. Really appreciate it