# Unipac Limpopo Black Sand



## GlenD (3 Jul 2019)

Hello

I'm looking at the Unipac Limpopo Black Sand to use as a cap on a dirt tank. While looking on here and online I've noticed a couple of people say that it HAS changed their tanks PH - one guy from 6.2 - 8.2. I'm in London and have high PH and will be using 50/50 RO/Tap and I don't want anything to raise the PH anymore?

All the product pages on Unipac Limpopo Black Sand say that it will NOT effect PH??


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## Aqua sobriquet (3 Jul 2019)

You could stick your head in this thread and ask:

https://www.ukaps.org/forum/threads/is-sand-sand.57971/#post-565823


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## dw1305 (3 Jul 2019)

Hi all, 





GlenD said:


> I'm in London and have high PH and will be using 50/50 RO/Tap and I don't want anything to raise the PH anymore?


If you don't add CO2? It won't raise the pH. If you add CO2 you might get below pH7 during the "CO2 on" period, but even then any extra hardness will <"precipitate out"> (as CaCO3) as soon as the gas is off.

If you don't add CO2 even your 50:50 RO:tap mix will be at ~pH8 and won't dissolve any carbonate compounds.

If you have hard water it won't dissolve any limestone, snail shells etc. you put in the tank. Have a look at <"Home Shelly Home">, about the shell beds in Lake Tanganyika.

cheers Darrel


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## GlenD (3 Jul 2019)

Thanks, as a safety measure, would it be worth soaking the substrate in RO for a few days a few times to actively remove any soluble elements?


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## dw1305 (3 Jul 2019)

Hi all, 





GlenD said:


> Thanks, as a safety measure, would it be worth soaking the substrate in RO for a few days a few times to actively remove any soluble elements?


It won't do any harm, but it shouldn't make any difference. If it is silica sand with an iron oxide coating, neither of those are soluble in hard, or soft, water.

Do you have a TDS (conductivity) meter? If you do then that would tell you fairly quickly if anything is soluble (TDS will rise). 

cheers Darrel


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## Simon Cole (3 Jul 2019)

Hi Glen, Hi Darrel, 
I use lots of Limpopo black sand for capping, and it doesn't change my pH. You can see that it is quartz grains, without any carbonate minerals present. It is not dyed. 
Darrel made a great point above. 
The only thing I have noticed is that there was a patch of crude oil in one of my bags, and it needs a bit of a wash. My guess is that this is shipped from Africa as wit the authentic product. I have never noticed any impact on fish, shrimp or plants and I think it is a very safe and really beautiful product, so 10/10. Enjoy.


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## Tim Harrison (3 Jul 2019)

it's pretty much inert...I've got about 30 odd kgs of the stuff sitting in my garage new and unused.


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## GlenD (3 Jul 2019)

dw1305 said:


> Hi all, It won't do any harm, but it shouldn't make any difference. If it is silica sand with an iron oxide coating, neither of those are soluble in hard, or soft, water.
> 
> Do you have a TDS (conductivity) meter? If you do then that would tell you fairly quickly if anything is soluble (TDS will rise).
> 
> cheers Darrel



Hi, yes good idea. Thanks


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