3M Color Quartz and Leleupi fry, the smallest of which have only just become free swimming that day, which should give you a good impression of the grain size.

What color substrate you use can make a big difference to how your fish look in the tank. Generally I would say very dark colored fish will look best over a light substrate and vice versa. This is kind of counterbalanced by nature though, because most fish have an amazing capability to blend in, that is if you put a dark fish over a light substrate, the fish will actually become lighter. I have clearly seen the opposite example with my Neolamprologus leleupi, whose bright yellow color turned a lot darker when they were placed over black substrate. So it could be said that to achieve the best color in your fish, e.g. get the brightest colored leleupi, you need to put them over a complementing, in this case light, substrate. While this is true, and probably a good point to take into consideration if you want to competitively show your fish or just make them look their best for sale at auction, to me a contrast between fish and substrate still looks best in a show tank, but this is in the eye of the beholder.

Enough of the philosophy, I wanted a black substrate for my big tank, and I found Tahitian Moon Sand outrageously expensive - at least at the stores in my area in NE Ohio. An alternative people frequently recommend is Black Beauty, which is essentially a waste product, and in my opinion this means you just don't know what you are getting. Since I have never seen Black Beauty marketed as aquarium substrate, there is also no reason to believe that it undergoes any quality control to ensure its suitability for this purpose. Maybe my background in chemistry makes me over-careful, but I am not convinced that some batch of it couldn't leach toxins into the water. Even a trace of heavy metal salts could kill off your fish in no time, so even if some people report long term success with Black Beauty in their tanks, this doesn't mean that you will be fine with the batch that you happen to buy.

This part tank shot includes a larger area of the substrate. It was taken in January 08, almost 3 years after the tank had been set up.

On Cichlid-forum I heard about 3M Color Quartz and found it to be the perfect solution - less than half the cost of Tahitian Moon Sand, and a carefully engineered product that's guaranteed to be chemically inert for long periods in the water and under UV light. Not even regular sand can offers the latter! Following the advice of people on Cichlid-forum.com, I rang a raft of pool and tile shops in my area, but none of them had ever heard of 3M Color Quartz. I ended up calling 3M at 1-800-447-2914 (the phone number is on their web site buried in the FAQ about Color Quartz). I was very lucky in that the 3M distributor of Color Quartz for 5 States happens to be located only about 30min drive from my home, and I bought the Color Quartz directly from them. Unfortunately they charged $22 for a 50 pound bag of black T-grade Color Quartz, which is slightly more than people have paid elsewhere in the US, but I still found it well worth the money and most importantly I wasn't hit with shipping charges, which would have been considerable since I needed about 200 pounds of substrate for the tank.

For those of you in or around NE Ohio, the distributor is N.T. Ruddock Company, 26123 Broadway Avenue, Cleveland, Ohio 44146, Tel: 440-439-4976, Fax: 440-439-8728. Either 3M (anywhere in the US) or this distributor (around NE Ohio) should be able to point you towards a store where you can buy the stuff.

When I bought it, I also saw the S-grade Color Quartz, which is finer grained and has rounder granules. The T-grade looks and behaves like sand, I definitely would not call it gravel, but it is comparatively coarse sand - not sharp though. The S-grade is very fine, more like a powder, and feels very, very smooth, due to the round particles. For pool applications, I believe they use S-grade if you want a very smooth surface. The T-grade is used where you want a bit of grip; e.g. on stairs. Both would probably work well as substrate, but I thought the T grade would look more natural - if that's possible with a black substrate.

The 3M distributor where I bought the stuff had a sample box with little test tubes full of different types of Color Quartz in all the different colors. There are some comparatively natural looking ones such as red and brown tones as well as forest green, but also baby blue and pink. Whatever your taste, you should be able to find a shade that you like, and I have also heard of people mixing colors, for example for a salt and pepper effect. 3M also had a similar product for roofing applications that was just a notch coarser than T-grade. I forgot the name, but it would probably act like very, very fine gravel. You might want to try and find a store in your area that has the stuff and check it out yourself. That's the only way you can find out which of the different options you prefer.

Addendum May 2018:

By now Color Quartz has been discontinued by 3M for a number of years, and is no longer commercially available. My personal substrate of choice is Pool Filter Sand, but of course it is only available in one color.