Here it is!
> I would like to know if I have a old aquarium with CC as substrate and is in the process of turning it into a DSB with Southdown Sand, would it be
> beneficial if I mix, say about 15% to 20% of my old CC into the new sand?
No, maybe 5 % max. The coarse material will "float" on the finer stuff. As animals rework the sediments, fine particles will move down and around the coarser material and simply lift it to the top. This has the effect of
creating a thin layer of CC that acts like rip-rap or armor rock, preventing animal access to the surface. Eventually the fauna under such areas tends to die and clumping of the substrate is a result.
> I do understand and are concerned about H2S build up in a total anaerobic
zone within the substrate. With the help of various sand borrowing
> organisms such as bristle worms, gradual releases of H2S on a slow but
continuous basis would certainly relieve the H2S build up. However, I know
> of proper tunnel building would be difficult to achieve if the substrate
is made up of entirely Southdown sand
No. That is a misconception. For most of the small sediment dwelling worms
and bugs this finer sediment is either near or at the optimal size, and they
move through it easily. Most of the animals will be in the top 2-3 cm of
sediment, but it is their movements in this zone which cause the water
movements (very slow movements) which distribute materials to the lower
parts of the bed. There is some H2S build up in the sediments, but it is
slight and not really a problem even if liberated into the tank.
>, wouldn't incorporating the existing CC into the new substrate 1) help
the borrowing activities of the microorganisms, 2) aid proper root growth of
macro algae 3) help
> speedy-up bacterial seeding of the new substrate, and 4) prevent the new
sand compacting into a solid rock?
Macroalgal attachment won't be a problem. They don' t have roots, by the
way, just attachment strands (which look like roots, but have no nutritive
collection function). Bacteria spread through the sediment very rapidly.
It will take very little time at all for the sediment to become colonized.
Addition of the CC will cause, not prevent, clumping.
Hope this helps.
Cheers, Ron
