huh.... once again....
Why don't you drive up and take a look at mine. Works perfect! What's your system run on.... (Chirp...chirp)
Useless banter doesn't help new concepts. 'Absurd' ideas end up the norm in many cases. I applaud your dedication to this style of system Shawn. Some people don't get there are many successful ways to maintain these glass money pits and only assume their way is 'The Way'. I tried your concept and it didn't work out for my system but I found one that did. Geez....sorry for the rant.:hmm3:
Thanks DeathWish. The problem with these long threads, is a lot of technical details get lost in the general conversations. It's too bad the forum doesn't have a highlighter to mark posts that are particularly helpful. The posts that are not helpful certainly stand out though
I have been experimenting with this system for a number of years now, with the hopes to prove or disprove its merit. Its very hard to prove that something works with so many variables in a reef system. It's a lot easier to discover that something doesn't work, but I have yet to do so with the Duplex system.
There isn't any one form of technology or methodology that can do everything you want, nor should there be. Protein skimmers are a great tool and I value their merits, but quickly see their defaults. I like the duplex system because it incorporates a number of simple, cost effective approaches in a small footprint.
1) The protein skimmer uses an "in & out box". Water is "first in first out" (FIFO). Freshly drained display water is staged in a partitioned area moved along to the second chamber via the protein skimmer. Most protein skimmers have a magic number of 1.33 x the volume of the tank for turnover. If you match the return pump from the sump to the feed pump of your skimmer, you can feed the second half of the duplex sump with via your protein skimmer. Alternatively to you run your display drain directly through your protein skimmer with an emergency/excess bypass to part two of your sump. This simple plumbing modification will trap detritus in the first compartment and insure it all goes through the protein skimmer, and only does so once before moving on to the next zone of your duplex. Since the partition and protein skimmer are physical barriers for aiptasia, it's a good place to keep them to assure they don't make it into the display. If you are nervous about keeping them there, substitute for mojano, or add some lighting and keep xenia there. Xenia are a very efficient nutrient exporter. Just make sure you don't grow algae in your protein skimmer.
2) A shallow mat of chaetomorpha or caulerpa grows much faster and more stable than a ball. Light penetration is exponentially better and there are no dead spots at the bottom where old growth slowly breaks down and pollutes the water. With the shallow tray you gain some real estate below for non-photosynthetic invertebrates. Water passes over and through all of the algae, so nutrients are concentrated. If anyone doubts that non-photosynthetic benthic inverts will further assimilate organic matter, then they can use live rock instead of eggcrate and focus more on fostering the growth of denitrifying bacteria. The idea of all anaerobic bacteria being nitrate consumers, and all aerobic bacteria being ammonia and nitrite consumers is false. Many aerobic bacteria consume nitrate, and many anaerobic bacteria produce nitrite and nitrate. In my opinion, real estate isn't the limiting factor of denitrification by bacteria. A sand bed in the tank and at least one pound per gallon of rock in the display is enough to meet these requirements. Some argue that denitrifiers are not limited by carbon, but the addition of a carbon source such as vodka has certainly given many people tangible results. Eric Borneman covers the topic well in this article
http://www.reefkeeping.com/issues/2004-11/eb/feature/index.php
3) Non-photosynthetic benthic invertebrates offer a greater biodiversity in your system. many of these organisms consume nutrients that would otherwise feed nuisance algae in the display tank. While some directly remove nitrate and phosphate, others do so through microbes that live within their tissue. A small handful of sponges are toxic, but no more so than the colonial polyps, mushrooms, and algae currently in the tank. None of these benthic inverts can be considered parasitic, and I would argue that they do not increase bioload significantly as they are opportunistic feeders, utilizing excess food that the display tank isn't using. Nature doesn't like empty spaces. You build an empty space in your sump and these benthic inverts naturally appear. If you added light, algae wold naturally appear. We already have a photosynthetic refugium above, why not increase biodiversity with a non-photosynthetic refugium below? We are only adding eggcrate as a site, no extra feeding, heat, energy, or other resources expended. These zones have always existed n our tanks, and have only been limited by space. The experiment is to remove that limitation and see what happens. So far there have been no reports of parasitic/pathogenic episodes, crashes, oxygen depletion, or increase in nutrients or TOC (dissolved & particulate organic carbon). The only negative reports I have heard from people who have tried the system is a build-up of detritus which is often attributed to mismanagement of the shallow tray above where the algae grows (allowing it to overgrow or making the water or algae mass too deep), or not using the settling chamber for mechanical filtration (aiptasia, floss, & settling). The criticism from people who have not tried the system has been limited to "it won't work", and "benthic inverts will add to the bioload and should be treated the same as corals in the display". While this is true in many respects, non-photosynthetic benthic inverts (can I say NPBI?) are niche opportunistic feeders that would not populate the tank if they were limited by nutrients. I would deem them as competitors to display organisms only if they required more nutrient import (feeding) to sustain, but they don't. The benthic zone promotes higher pod populations and greater biodiversity for a naturalized system.