# Limestone in hard water



## OllieNZ (28 Aug 2011)

Hi All
Im consdering using limestone more specificly cotswold stone in my next tank. The water is going to be straight tap which has a ph of 7.5 and 250+ ppm ca. I was wondering wether the stone will add to this futher and end up disolving i'd hate to have it disapear after 6mths.
Thanks
Ollie


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## dw1305 (29 Aug 2011)

Hi all,
No, you are perfectly safe, the water is already fully saturated with calcium carbonate, so no more will go into solution. 

I've got a picture somewhere of the shore line of Lough Bunny (in the Burren, Co. Galway, RoI), when the water level was lower than normal, where you can see a perfect division where the normal water level is. Above the line the limestone is eroded into karst features (micro-karren) by the rain and below the "tide" line (where the water is calcium carbonate saturated) the rock is so smooth it looks like it has been polished (just found an almost identical one on the web).





The only thing to watch for is that you need to make sure your rock isn't too freshly quarried as the yellow "Bath stone" is very soft when freshly quarried. 

cheers Darrel


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## OllieNZ (7 Sep 2011)

Thanks Darrel
Great tip on the bath stone
Ollie


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