Sand

[0pius]

I noticed today a company in West Auckland selling white sand from the East coast, would this be any good for aquarium use.

Also could you use black sand say from Muriwai beach for a tank.

[wasp]

Pretty much any NZ beach sand is fine, but may need a good clean.

Also the grain size will often be too small, best to get it yourself, on some beaches the tide has sorted it into areas of different sizes so you can get what you want.

[puttputt]

The black sand on west coast beaches is Iron based. You don't want it in your tank!!

[0pius]

Okay wont grab from Muriwai then. Just trying for a different look as I am feed up with CC sandbed

[wasp]

CC is not the best IMO because it can accumulate & hold even more waste than normal sand, and it is within the pores so even vacuuming cannot get it out. There are other opinions on this though as some people want a biologically active sand.

A few years ago I set up a tank that was a Muriwai biotope, with all the inhabitants gathered from Muriwai. Was a little 2 footer, cold water, and had some of those really nice anemones. Unfortunately I did not have a camera then I wish I had some pics of it. For the substrate I used a mix of crushed shell and black sand, both from Muriwai. Never tested the water for iron but there did not seem to be any issues. As the sand does not actually go rusty, I assumed it must be bound in some inert form, although I don't understand the chemistry of that sand.

What I found though was it looked good at first, but the sand was very fine & fell down below the crushed shell, which all came to the top. Eventually I replaced the whole lot with aragonite.

[puttputt]

I studied Iron sands during my metallury degree, and although the Fe is bound within the Magnetite (or within the Titanomagnetite in NZs case) a small amount can leach into water.

Of more concern in a tank situation is its magnetic properties. It is highly magnetic, and there is no way I'd want that around any of my pumps.

[wasp]

Good point Puttputt.

When i used to use iron based phosphate resin, the pumps would clog up quicker than normal, and the buildup was orange or brown. I just assumed that some iron was getting mixed in with the calcium deposit, but now you mention magnetism, that may well explain why the iron tended to accumulate in the pumps.