Limestone?

880 Views 5 Replies 4 Participants Last post by Ed, Nov 17, 2011

dubvstudent

Discussion Starter · Nov 16, 2011

I'm planning on using a lot of limestone to boarder a water feature in a tank I'm about to build. Any problems with that? I know it will buffer the water over time and increase the ph but will it have any other negative consequences?

Also, it will be gathered locally. Most of the lake Ontario bedrock is deeply pitted Limestone and scarps of that are what I'm looking for. How would you treat it? I'm thinking soaking a day or two in a bleach solution than setting in the sun for a few more to dry.

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mattolsen

· #2 · Nov 16, 2011

I would totally stay away from limestone. I can't say for sure that it would be bad but I'm fairly certain it might. When I was a chef we used to use limestone to line the bottom of containers holding stuff that needed to be kept dry. The limestone was supposed to be the part of the equation that helped keep the moisture out. Now I don't know if it would drastically reduce the moisture but I'd at least look into it before hand. Good luck, and let me know what you find.

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InHoc1855

· #3 · Nov 16, 2011

In a closed circuit ecosystem such as a vivaria, i would guess that Limestone (which is mined to create concrete) would dramatically increase the pH of your water. To neutralize it you would need to add acidic water, which (im not positive of this) will eat away at your limestone.

Central and south america have tons of limestone mountains/rocks but it is continuously flushed to sea by rain as well as countless other factors that would aid in making it suitable to support the local flora/fauna.

I would strongly suggest not using it. pH neutral rocks are the way to go.

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Ed

· #4 · Nov 16, 2011

weathered limestone often has a surface layer of insoluble salts which reduce leaching of the anion which significantly reduces the impact on pH. I would suggest not soaking it in bleach but instead soaking it (if you can get it) a strong solution of trisodium phosphate. This will drive a reaction that converts surface carbonates to the much more insoluble calcium and magnesium phosphates. This may not be ideal as some algaes can use this as a food source by digesting the phosphate off the rock. In any case if you use a false bottom and do not let the substrate and water layers touch, any impact on pH is not going to be an issue. Some of the clays used by people in thier enclosures as substrates have high pH values of water once it passes through them (in some cases over a pH of 8).

Ed

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dubvstudent

Discussion Starter · #5 · Nov 16, 2011

Ed said:
weathered limestone often has a surface layer of insoluble salts which reduce leaching of the anion which significantly reduces the impact on pH. I would suggest not soaking it in bleach but instead soaking it (if you can get it) a strong solution of trisodium phosphate. This will drive a reaction that converts surface carbonates to the much more insoluble calcium and magnesium phosphates. This may not be ideal as some algaes can use this as a food source by digesting the phosphate off the rock. In any case if you use a false bottom and do not let the substrate and water layers touch, any impact on pH is not going to be an issue. Some of the clays used by people in thier enclosures as substrates have high pH values of water once it passes through them (in some cases over a pH of 8).

Ed

Thanks Ed. I'm not familiar with trisodium phosphate, Is it very different in usage than sodium phosphate? Isn't sodium phosphate the active ingredient in alot of powdered detergents? Could I just wash/clean up the rock in that and then rinse well/ sun dry?

I personally like rock work that is more or less uniform. I have thought about using granite (also a ton of that on the shores of the lake) but granite is so variable in appearance that it is hard to get enough of it that looks similar enough to "tie the tank" together.

Granite is however, to my knowledge, almost always neutral (or at least will not buffer the water) so if limestone is gonna be a pain in the a$$ I guess i will just avoid using it.

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Ed

· #6 · Nov 17, 2011

Products listed as sodium phosphate could be any of the following, sodium dihydrogen phosphate, disodium hydrogen phosphate and trisodium phosphate. All will bind up the calcium but the Ca3(PO4)2 is going to be the least reactive of the potential salt combinations.

If you can get flattish pieces of granite don't forget that you can layer them (even if they are different color) which will be natural looking as it would mimic strata.

Ed

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