Recommended substrate for cherry shrimp?

[ShrimpDuck]

Can anyone recommend somewhere to get a dark, inert gravel for cherry shrimp? I've got various coloured cherries and rilli's and have had a few deaths. I'm current using fluval stratum, but after discussions with a very competent shrimp keeper I think it could be the substrate that is not agreeing with them. Any suggestions would be greatly appreciated!

Edited August 29, 2015 by ShrimpDuck

[2OFUS]

Tahitian moonsand is awesome for an inert gravel 

its online everywhere 

Edited August 29, 2015 by 2OFUS

[fishmosy]

I'm using Pisces Iron Sand which is (as the name suggests) a sand rather than a gravel, but has the dark colour that you are looking for to make shrimp colours pop. 

Edited August 29, 2015 by fishmosy

[StanJam]

I find that Flourite really helps the shells of inverts including shrimp.

They have a black sand which is very nice. I use it for my red crystals.