How do i get hard water marks off?

[monster]

If you mean when the frogs are out of the tank and your doing a big clean you can use a razor blade then do quick scrub with vinegar and warm water on the little bit that is left and that should do it. You hold the razor blade like as if you were scraping paint of something so it is flat against the glass with a little tilt to it so the edge wont scratch the glass. I got a used tank once from someone who kept fish in it and the hard water buildup was incredible, my brother in law is big into the fish hobby and he told me this trick and the tank looks like new.

[Lija]

Yes, that's exactly right. Some water marks are fine, I have to scrub everything every month or 2, the water here is awfully hard. So I do this:
spray some water
scrub like Cory said
wipe with papertowel, spray some more water, wipe it clean
take my very much loved zilla terrarium cleaner, spray it, wipe to dry, like you would with windex.
done.

edit - and im pretty sure OP could not care less, the thread is 3 y old lol

[bcreps]

i use vinegar but i think i will be using lemon juice now as that sounds alot better. i hate the smell of vinegar and it takes abit to rinse it out. and the question asked wasnt directed to the op lol