"Crud" around top of tank? Safe?

[DHodges34]

This is a picture of a tank that I plan to use as a sump, I got it from a friend who used it with freshwater, and never used any sorts of medicines so I don't have to worry about copper or anything.

Does anyone know what the stuff around the top of the tank might be? It kinda looks like soap scum?

Thanks.

- Daniel

[JG1]

why don't you just get a razor blade and scrape it off if your worried about it.

[H@rry]

It's probably calcium deposits. It should be harmless but you can put a paper towel over it and wet the paper towel with vinegar. Let it soak a while and it should wipe off.

[crab0000]

It could be hard water deposits. It should scrape off with a razor blade and some vinegar.
Steve

[DHodges34]

i didn't even think about that, thanks a lot everyone

[sw-addict]

It is calcium deposits from running the tank with low water. A friend of mine just picked up a 90g freshwater that was only half full and had those line all over. He cleaned it with CLR and had all of chiclids in it (for 2 weeks) his fish are all fine. He said that it just washed off, if your going to try this I would read the label.