Limestone in a pond?

[kayoss]

Hi Guys

I have a rockery/water fall feature on my pond (pink/red granite) but am thinking of changing it to a grey coloured limestone. However, I seam to remember someone in the dim and distant past telling me that limestone shouldn't be used for koi ponds - any advice greatly appreciated!

Thanks in advance

Bob

[eds]

Limestone will raise the pH of your water and your TDS. I'd want to use something that is neutral so it doesn't affect your water chemistry.

[kayoss]

Hi Ed

Thanks for that. My pH is already high - usually around 8.2-8.3 so pretty hard anyway. Is such a high pH likely to have any significant affect on either the limestone or my water parameters?

Cheers

Bob

[boogatee]

Limestone is basically Calcium Carbonate and it has a natural pH of 9.2 .... I've managed to find this - http://www.engineeringtoolbox.com/bases-ph-d_402.html which confirms the pH value.

I also know that it can be sealed and used, but sealing requires that it's monitored to ensure that the protective coating is maintained. Since limestone is relatively soft, it makes construction easy and is often a first choice in decorative pool environs, but being soft is also a disadvantage as running water will cut into it and so it's generally sealed to minimize this.... now thinking about a koi pond, I would propose that sealing would not only prevent cutting into the limestone but also prevent it being dissolved into the water and raising your already high (some might say normal ) 8.3 to 9.something

[eds]

Bob, as Syd has basically said on the BKKS Forum, if you have a high pH, hard water and do plenty of water changes then a small amount of limestone isn't going to make a huge difference.

But the limestone Will slowly dissolve so bear that in mind.

[kayoss]

Hi Guys

Thanks for the replies.

Must admit that I was looking for a cheap option in going down the limestone route, but now have permission to go for the granite option - at least I think "I dread to think how much the bloody pond has cost anyway, so why worry about saving money now!" means I've got permission!!

Anyone know the cheapest place to get a tonne of granite (green or grey) delivered to Dunstable??

Thanks again

Bob