Onyx Sand vs. Tahitian Moon Sand

[Aquarius0015]

I am interested in SeaChem Black Onyx Sand (will affect pH), but the local Petsmart also sells "Carib Sea Black Tahitian Moon Sand" which is cheaper(claims not to affect pH). I have medium hard water already, and I like to keep plants, but nothing serious- java ferns, java moss, aponogeton, water sprite, etc. Maybe crypts soon. Which type is best for my situation?

[Cearbhaill]

I have Onyx sand in my Discus tank (doesn't affect my pH or KH at all BTW).
When I was setting up I couldn't find enough Onyx sand so decided to bulk the substrate up a bit with the Carib Sea black sand.
To make a long story short I never could get it rinsed well enough to bear putting it in my tank- it just kept making black sludge in my rinsewater.
I threw it all away and waited for the Onyx sand.

[Dopey]

I'm toying with the idea of changing my substrate. (I currently use pool sand with laterite gravel mixed in.) Do you have any pictures of how this black substrate looks? I'm intrigued. What are its qualities as far a plant growth?

[Aquarius0015]

Here is a link for the Tahitian Moon Sand:
http://www.drsfostersmith.com/product/prod_Display.cfm?siteid=6&pCatId=7324

I've seen it in bags at the store, but the plastic is hazy and I can't get a clear idea of what it looks like. Same with the Onyx, but at least I've seen online pics of tanks with it, and they're gorgeous.

Last night I added Play Sand (a whopping $3 investment). Although it would be nice for other set-ups, it's too light and really washes out the colors of my vibrant red betta. Now, what am I going to with the wet sand in the tank plus the remaining 40lbs or so?

I have a pH of 7.4 from the tap, and as I said earlier, my water is on the hard side (do not have an exact measurement for ya, sorry). However, I am interested in this sand for a tank containing cories and labyrinth fishes (acidic, soft water conditions preferred). I guess I could do partial water changes with Brita filtered water (as it is softer b/c it has less minerals), but maybe it would be best to filter with peat, too?

Just noticed the brand in the link is not the brand I'm discussing, but it's close enough.

[Aquarius0015]

A few other things (sorry, I know I can be long winded)... How much onyx should I add for a 5.5 gallon? It comes in 7kg bags which works out to roughly 15.4323584 lbs. One bag should do it?

Dopey, I hear it's one of the preferred substrates for plants.

[aquabillpers]

Aquarius,

You don't have to worry very much about a pH of 7.4 hurting your labyrinth fish and corys. The only time that pH is significant is if you want to breed a some fish, but even there most do just fine with any pH.

Bill

[Aquarius0015]

Thanks aquabillpers. I just didn't want to risk the 7.4 mixing with the onyx and creating some sort of chemical disaster for my beloved fishies.

I just called Petsmart. $25 for a 15lb pound! It's like black sandy gold!

[RTR]

But don't expect Onyx sand to be black - to my eyes it is anything but black. Light grey, maybe, at best.

[lesley]

$24 might sound like a lot, but I just asked at Big Al's and although their per bag price is only about $14, the additional shipping charges are hefty. I asked about getting five bags shipped to me in California and the shipping cost alone was over $60. It might be better to suck it up and pay the $24.

[Aquarius0015]

I just got home from a LFS five minutes ago (I'm addicted to this forum). I just had to let you guys know the good news. I got a 15.4 pound bag for $20. If it's not enough (which it should be I think), I'll just mix in a few pounds of diamond chips-- maybe a little bit cheaper lol.

[Aquarius0015]

Now to get rid of this play sand that is currently in the 5.5 gallon. Any suggestions?

Edit: The bag says it is sufficient for a 10 gallon tank at 2" so I will be fine. Is onyx sand like reg. sand in that it cannot be too deep or it will develop anaerobic pockets? I'm not sure if the additional courseness prevents this or not...

[Cearbhaill]

If you are going to try switching substrates on a working, stocked tank- I had very good luck using a (new) dustpan to get out the bulk of the old stuff. Then siphoned out the residue.

But with a 5.5 gallon I think removing the occupants (and water) to a clean garbage can would be much easier- unless I am misunderstanding your question.

[Aquarius0015]

I managed to get it all out, but it took a while. I drained the water, took out the shrimp and betta, then scooped up sand with a cup. Then I filled and siphoned the tank until there was just a trace residue of sand on the sides, and I rinsed it under a shower.

The dark grey clouds caused by the new onyx sand scared me, but it settled down overnight, and now looks great except for a slight layer of grey dust on the surface of the gravel and the plants. I wish I had decided to go with onyx before. It's expensive, but much nicer than gravel simply in terms of looks (and there's the plant benefit, too).