<a href=showthread.php?s=&postid=9115786#post9115786 target=_blank>Originally posted</a> by Redstratplayer
IYHO About How many inches of egg crate per gallon would be best ?
Also do you think i would be better off with a skimmer or a zonal sump?
Steve Tyree says that a filter feeder zone is needed to.
Do you think that i could place filter feeders like fan worms in a cryptic zone?
Is a filter sock needed and if so what micron?
Your questions seem like simple ones but there are many layers to these decisions.
No magic number yet for egg-crate quantity. I've been using a 3" space between the rows, and running them perpendicular to the direction of flow. The 3" space seems like a lot for the first 6 months, but once the colony grows, you can see that the worms fill the egg-crate lattice and stretch to the neighboring panels 3" away. You could always start with twice as many and remove them as they populate. The benthic zone is one of nutrient reduction and conversion, not one of export. Most benthic invertebrates grow slowly, live long, have little mass, and convert rather than bind organics, so there is no major benefit to their harvesting.
I've recently tried a version with panels that run parallel to the water flow. I won't know the results for a while. The benefits are the ability to fit a siphon hose or seeded rock in through the end, and the egg-crate is less likely to trap detritus. The possible negative aspect is that the sessile (stationary) critters don't receive direct flow as they are sheltered within the structure, but this may prove to be beneficial as they don't like flow anyway.
I still use a protein skimmer with naturalized systems. The beneficial organisms themselves cause harm through the release of toxins (allelopathic competition). Algae and sponges release toxins in the wild, and it quickly dissipates as it drifts into the abyss. Closed systems don't have this kind of dilution, so chemical filtration is necessary. Protein skimming, ozone, UV sterilization, and molecular absorption (carbon & ion exchange resins) are all methods of chemical filtration that aid in the ability of naturalized filtration systems to function efficiently. It sounds paradoxical to say that you need a mechanized system to run a natural ecosystem, but that's the case.
You can forego chemical filtration once the ecosystem is balanced. You could either remove existing equipment, or go the patient path and go natural from the start. My clients don't have the patients to wait a year for optimum water quality, but they have the money to make up for it. They want instant gratification, so that's what I deliver.
There are sound arguments against the use of protein skimmers, mechanical filtration, and ozone & UV. The main ones are cost, clutter, and the fact that they can "over-skim", robbing beneficial organisms of nutrients. Mechanized filtration methods are complimented by the myriad of filter foods available on the market today. It would be great if we could produce our own foods within the benthic and refugium zone and have self-sustaining ecosystem, but we're not there yet.
Up until recently, filter feeders like sponges, gorgonians, chili sponges, dendronephthya, crinoids, and nephthia, required natural nutrient rich systems that excluded the ability to keep corals that require pristine nutrient-poor water like many of the SPS. A very large Duplex system or refugium on its' own would produce enough zooplankton to support filter feeders. The cost of such a system is relatively low, but space restrictions would exclude it for most hobbyists. With 200 gallon sump on a 100 gallon display tank, the display is the refugium as corals are kept safe from algae and cleaner invertebrates.
There are many successful skimmer-less systems out there, but they require a more delicate balance of livestock, feeding, and patience. I've done skimmer-less tanks over the years with mixed results. Once they have a nuisance algae problem, I break down and add a skimmer.
I chose the term benthic zone for the in-sump Duplex design, to differentiate from Steve Tyrees in-tank cryptic zone, but they are essentially the same thing. Steve received a lot of criticism for coining the term "cryptic zone", so I stayed away from the controversy and commercial branding.
Benthic or cryptic zones are designed specifically for filter feeders, with detrivores as secondary residents. Sponges, tunicates (sea squirts), and fan worms will populate the area on their own, so your question about adding them is moot.
Filter socks, or any type of mechanical filtration depends on the demand. Good circular and or laminar flow will keep detritus suspended indefinitely. 50-100 micron filter socks will remove a lot of the visible particles (POC), but they clog
VERY quickly. I find good old fashioned filter floss (polyester fiber fill) to be the best because it's cheap, allows for bypass when clogged, versatile (you can cut it to fit anywhere), and low maintenance (you just throw it out rather than rinse it as you would a sponge). Any reports that this will cause residual nitrate are erroneous.
Older books will advise you to remove mechanical filters to allow for free flow of detritus to the skimmer and corals, but with todays foods, corals don't have to rely on detritus for nutrients, and we need to remove excess food that is suspended by modern flow patterns. Take a look at this series of articles about flow.
http://www.advancedaquarist.com/2007/1/aafeature They address the same idea that quality is more important than quantity. Traditional, poorly thought-out, flow patterns with impressive GPH, are a thing of the past.
Let the low life (me with my low level systems) make some noise: 
