LS grain size and critter friendliness

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In Memoriam
Gerry's point is well taken, but...

The small stars and amphipods are not the major actors in your sand bed fauna. Those animals are the small polychaete annelids, nematodes, flatworms, and other interstitial and sand animals, as well as foraminiferans, other protozoans and bacteria.

Generally with a decent mix of grain sizes in sand, the larger particles will soon migrate to the surface. They do this in response to sediment disturbances such as burrowing. The larger fauna such as the amphipods, small ophiuroids (brittle/serpent stars), etc., will occupy this level of sediment and move food and detritus through and into it. The other sand fauna will occupy the finer sediments beneath it and will continue the processing. Bacterial processing (i. e. the biological filter) is maximized in the fine sand under low oxygen or anaerobic conditions.

Coarser material provides only for one component of multicomponent systems.

Most commercial systems use coarser material as it resists the continual disturbance factors introduced in these systems by harvesting, etc. It really isn't the best stuff for you to use in your systems.

Cheers, Ron

While I beleive Gerald that some of te larger infonna benifit from a courcer substrate, I really don't beleive that it invalidates your decision.

I have a high flow area in the front center of my tank that I have Aruba shell in to prevent the substrate from moving. I have observed mini-stars and scuds are most visible in this area. However, most of the worms, bi-valves, etc are smaller and benift from the finer substrate.

Between my tank and refugium, I have several different sand sizes in specific areas.
You may decide to do the same. Remember, you are looking for diversity, not maximum numbers of large, visible infaunna. On the other hand, IPSF is trying to maximize the growth of the larger items to sell. Both valid, just different.

Sorry to ramble;


Thanks guys, that makes perfect sense. I guess I always thought I didn't see worms or brittle stars often because my current 2mm substrate was inhospitable. I think Gerald's mail has convinced me it was probably another factor, such as my hawkfish, which attributed to their scarcity. And, being as biological filteration is my real aim I don't regret my decision for the "big change".
On this note, our marine club was talked to by Bob Goemans about the Plenum system. He also advised using larger grained sand (2mm-4mm) because of oxygen exchange issues with the smaller stuff. He showed us his tank with loads of spaghetti worms living in it as well (using this size sand). Just thought that was a somewhat interesting tidbit I would throw out there. He did give a very interesting talk, not much info other than the science behind a plenum and how to set one up. Most of his talk was, "see this is my tank on a plenum, dont you want to use one too?". Admitidly, he did have a very nice tank :).
Very interesting, I got a mail from Gerald at IPSF today. I was advising him of the changes I was making to my tank. In a previous thread I was convinced by Ron to dump my current substrate in favor of an ESV/Caribsea oolite mixture. I contacted Gerald and mentioned my changes and that I may place an order next year. Take a read:

"Ron Shimek would have no way of knowing this as he has not seen our farm, but
all of the invertebrates harvested from our commercial production tanks,
including ReefWorms, Reef Amphipods and MiniStars, are raised on very course
substrate, including a lot of 3 mm crushed coral grains, plus rubble and
shells. In our experience course substrate size does not limit their
reproductive success, rather the opposite seems to be true. The dozen or so
tanks we have with fine grained substrates produce fewer sand-dwelling
invertebrates, not more."

The amphipods doesn't surprise me, they'll breed anywhere including the rocks. But the worms and mini-stars does. What about you?
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