White Residue

[radioman]

I used to have goldfish and when some water evaporated it left a white residue substance on my tank that I am having a really hard time cleaning off. When water touches it u cant see it but when it dries it comes back so should i just leave it alone and fill up my tank or does someone know a way to get it off.

 

[mlawson]

It's limescale from the water, normally I just increase the water level.

 

[Aphotic Phoenix]

As water evaporates it leaves dissolved minerals behind. I just scrub it off with a toothbrush.