depends on the look you want.
pool filter sand will give you the beach, tropical look while the black sand will give you the more brackish (sometimes, but not always) feel and or volcanic regions... or i have seen it done a lot with cichlids.. but that is with either or.. (always like black sand with them.. makes their colours pop)
pool filter sand will look dirty faster because of the colour difference, as the black won't.
i've only had the play sand, not the black but that one looks nice. i have the dirt substrate with small black gravel and love the look of it. so i'd pick the black sand.
Both have their merits, plants stand out on black & some fishes colour becomes more vibrant, pale sand lightens the tank & has been said highlights wood & rocks, some fish however can look washed out with a pale substrate.
I have black in a couple of tanks & natural sand in others.
I don't know if you're intending to have any corydoras or loaches in your tank but, if you are, I would go with the pool filter sand. I'm on my third (or fourth?) different black sand now, and I've noticed while my cories were feeding earlier that they're starting to lose their barbels
I was sure this was smooth enough (it's Pettex Roman black sand, in case anyone else is looking at it). It looks great, but I'm going back to playsand. My pandas are on it and their barbels are really long. Hope the others grow their's back
The stuff I tried before this turned out to be volcanic and was full of sulphur; killed two BNs a cory and three glass cats. Luckily it didn't affect my neons or hatchets.
Good point Fluttermoth, some black sand isn't good for bottom dwellers, Unipac Limpopo is cory friendly I have it in a couple of my cory tanks & they have lovely long barbels
Thanks for the heads up, I'll have to be extra careful as there'll be geophagus in the tank. I've been looking at Limpopo & Carib Sea's Tahitan Moon Sand. Hopefully one or both of these will be fine enough and smooth enough for geos. If not, then it's back to pool filter sand.
Just a thought... I use petco black aquarium sand and for about 6 months I had six julli cory cats which turned into 12 after breeding and all of their barbells were fine. So what makes the Tahitian moon sand unsafe for bottom dwellers?
It's too sharp. I used to have a close up pic of it, but I can't seem to find it now! It used to say on the Caribsea website 'not soft belly safe', but they've changed their website since then, and those warnings aren't there any more (not just for TMS).