Adding Chalk to my tank as a calcium additive?

[keyozoxmfc]

so today i was in biology class and was tired and falling in and out of sleep as always. we were talking about the nitrogen cycle and the carbon cycle etc. then something about limestone and calcium carbonate came up. and of course that rang a reefing bell in my head. and then she told the class that chalk used for writing on a blackboard is pure calcium carbonate. and it will dissolve with vinegar. she even said it says its on the box that its calcium carbonate.

so my question is..would this be a good supplement for a reef tank? could it be used like pickling lime in kalk?

just thought id share that with you. but i guess if it was something handy for a reef everyone would be doing it by now, but it doesnt hurt to ask

[George]

Unless you're thinking of having the school fund your kalk needs:evil:, I'd think that pickling lime would still be cheaper. Is chalk formed purely by pressure or is there some glue involved?

Come to think of it, all that eraser clapping back in 2nd grade was probably not the best thing for my lungs ...

[Phurst]

That's what i was wondering, if there is some kind of binder used. If not, i guess it might work in a Ca reactor, but if it's pure calcium carbonate, it shuldn't readily desolve in tank water with a pH in the 8.0+ range. Otherwise all our LR and aragonite sand would desolve too.

[keyozoxmfc]

ohhh yeah couldnt you dissolve it in vinegar though? well yeah i just thought it would be kinda neat if that worked. haha i might start stealing chalk from school =)...even though most teachers use dry erase these days. i would think that chalk is compacted calcium carbonate since you can write with it..because if it was glues wouldnt it break off into pieces as you write?