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joj27
08-18-2015, 01:04 PM
Hi, i have some large pieces of slate that has alot of rust on the surface. Is this normal for slate and is it safe to use in my aquarium?

TasV
08-19-2015, 05:10 AM
Assuming the rust stains were not made by something ferrous being in contact with the slate... it is normal for some forms of slate to develop rust-like stains. In fact, iron content is one of the determining factors in what colour slate will be. The iron can be in the form of minerals, such as pyrite (iron sulfide... fool's gold) and cleaning often isn't successful because it is part of the mineral make-up of the slate. If it was me, I would be scrubbing whatever loose material off that I could and then soaking the slate for an extended length of time to leach out whatever I could and then I would use it without any hassles. Don't add various chemicals, like CLR Clear, to it thinking it will remove the rust stains because if it's natural, from the mineral composition of the slate, it won't work and will just be absorbed by the rock making it hazardous for use in an aquarium. Bleach probably won't work either. If you use bleach make sure you soak it for a while in water as the hypochlorite in the bleach is highly volatile and so will dissipate quickly.. but it probably won't work. Don't do this in an aquarium (sans fish of course) because bleach can harden the silicon glue in your joins resulting in a lose of flexibility and eventual leaks.

joj27
08-19-2015, 07:16 AM
Thanks for the info. I bought it off ebay with some driftwood for 99p bargain! And it was previously used in the guys tank. I wanted to check it was safe to use incase it had wiped out all his fish hence him selling it. It's not flaky at all, more stained n if I use a scouer to scrub it I can smell the iron. Think I will try to scrub off as much as poss, then soak it in hot water b4 using ☺