firespook Posted August 26, 2007 Report Share Posted August 26, 2007 I got a whole lot of rocks from down by the Waimak (in chch) and just want to check if they are suitable for my freshwater tank. They aren't riverstones, I think they have been brought in from elsewhere to build the stopbanks? I'm pretty sure it's some sort of igneous rock, it's quite holey in some places, like it was air bubbles in the rock. I read somewhere to check it with white vinegar to see if it fizzes.... just have to buy some vinegar first.... here's a pic, does this rock look ok?? Quote Link to comment Share on other sites More sharing options...
Caryl Posted August 26, 2007 Report Share Posted August 26, 2007 Do the vinegar test on it. With lots of holes like that it will be porous and may leach lime which will raise the pH (good if you have Africans though). Quote Link to comment Share on other sites More sharing options...
jn Posted August 27, 2007 Report Share Posted August 27, 2007 I think one of the Alan's said you could use the HCL from the Ammonia test kit bottle if you have that. Quote Link to comment Share on other sites More sharing options...
tHEcONCH Posted August 27, 2007 Report Share Posted August 27, 2007 It looks like weathered Rhyolite off the Port Hills - If you wash it thoroughly it should be fine, but watch out for bits with redish patches - that's oxidised iron. You can always leave it in a bucket of water for a week and then measure the water parameters to see how its been affected. Quote Link to comment Share on other sites More sharing options...
firespook Posted August 27, 2007 Author Report Share Posted August 27, 2007 thanks everyone, I'll see how I go! Quote Link to comment Share on other sites More sharing options...
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