Please give people more time to answer until you "bump" your own topic. If you do not get a response after a day or so, go ahead and bump it.
To answer your question...think of it in terms of light penetration. MH
lighting is more "intense" or focused then CF
. This will cause the light to penetrate deeper into the aquarium. As a result, you will have more useful light make it to the bottom of the tank. In the example of clams that you gave, the answer is a bit tricky. There are clams that require MH
for best results. T. corcea
clams for instance. There are also clams that do not require as much light, such as T. derasa
or T. squamosa.
Here is the catch...the latter two are substrate dwellers, they still need lighting that will penetrate all the way to the bottom of the tank. So while they require less light, MH
is still preferred. It really just depends on what you want to keep. You made the right choice going with MH
, it will allow you to keep a wider variety of animals.