Duplex sump concept

[nanokeeper]

mr.wilson - I really want to thank you for your contribution to the marine aquarium hobby. I watched your video on this sump design and read this thread. After researching this subject even more I've decided to incorporate this design into my upcoming 90 gallon build. I remember the first reef tank that I setup years ago (only 10 gallons) was full of sponges and tunicates. Now I know why that tank was so successful.

Please keep us updated as you learn more about this topic. Thanks again.

 

[dendro982]

My 5g Duplex refugium in progress:
Feb 06_06 - nice and clean, a lot of foraminiferans and sponges was added:

Chaeto is not blocking outflow, it only seems so, the tubing is behind.
4 months later, cleaned in between, of course, but a lot of debris and chaeto fragments go under the eggcrate:

Flow is along the diagonal of the tank - from far to close to the sump. The thick tubing is outflow:

160 gph for 5g. Red cyano flourishes on the top of chaeto.

A couple of months ago started to supply this refugium by skimmed water, all the same. Skimmer is oversized for 90g (ASM G-3), main tank is heavily fed 3 times daily, nitrates within 40 ppm, phosphates (before phosphate remover) max 0.5 ppm, no ammonia or nitrites. Light for this refugium is 27W CFL 6,500K.

More details:
LR rubble sheds a lot even without feeding the refugium, dead pieces of chaeto almost impossible to siphon out through the eggcrate:

Red cyano:

Acoel worms and red cyano on the top of this chaeto:

What am I doing wrong?

Refugium, supplied by skimmed water should be clean, in my dreams, may be
The layer of chaeto is not so thick to die from the lack of light...

Thanks.

 

[mr.wilson]

The chaetomorpha is the source of your detritus. It grows well at the surface, but the lower (shadowed) regions have a constant die-off.

Chaeto is also more condusive to breaking off into a small thallus when growing conditions (light) is limited. These small "braches" slowly decompose when trapped in the dark benthic zone.

I would switch to a caulerpa. It won't crash or slowly die-off as long as you continue to harvest it, keep an 18 hour (summer) photoperiod, and don't allow it to ball-up.

A fine mesh would stop the detritus from migrating down to the benthic zone, but the benefit of allowing it to filter through is that you can monitor it's removal, or lack there of. Standard refugia have quite a bit of detritus under the macroalgae but it's out of sight and out of mind, swept under the carpet. The benthic zone is more like hardwood flooring than a carpet. Every bit of dirt is there to see, so you have to do something about it.

Fan (tube) and bristle worms will remove the unavoidable detritus. predatory starfish like chocolate chips and green (fish eating) serpent stars will also do a great job of cleaning up. Reef-safe inverts are never as voracious at removing detritus as "bad guys". Aggressive hermits and other crabs are also useful.

The cyanobacteria will go away once the caulerpa starts to grow well (oxygenation). I use those same bulbs. The price is right, they run cool, they're compact, easy to replace, and give good growth, but they do tend to encourage red slime algae growth. You could add a small powerhead to direct water across the surface until it goes away.

 

[dendro982]

Thank you, Mr. Wilson! Will do that.

The only there will be problem with 18 hrs light - the light will leak to the main tank, refugium and sump are free standing, at the side. Building enclosure will restrict ventilation, adding fan adds noise...

Could be there other solutions, to keep things simple?

Sorry, I'm not wanting too much, just trying to keep this approach to reefkeeping in general, just like some prefer MH sps tanks or cold water tanks.

 

[mr.wilson]

An 18 hour photoperiod uses the maximum amount of daylight hours with the minimum amount of respiratory dark period. This doesn't mean you can't have an 8 or 12 hour day. It's consistency that matters.

Seasonal changes are cues for caulerpa to reproduce. Changes in photoperiod will simulate the shorter days of winter and cause it to go to seed.

I would go with 12 hours if you can get away with it. It sounds like a reverse photoperiod isn't possible in your case. Do you experience significant PH drops at night?

 

[dendro982]

I can do 13 hrs, it will be like dusk and dawn for a fish, and shall watch for a signs of caulerpa, starting to reproduce.

Really can't say about pH drops at the night, the pH tests I tried show contradictory results, so I can't rely on them at all (Hanna pH probe, Seachem Marine Basic, API, Nutrafin).

Anyway, the amount of algae is not so big, the maximum ever was ball of chaeto 3 gal size for 90f tank, now much less because of the constant discarding the top, covered with red cyano. Fish is not visibly bothered, corals (LPS and softies) too.

Thank you very much for the advice on keeping refugium clean, really appreciate this. I thought, that the battle was already lost.

BTW, grape caulerpa replaced the chaeto today, with added aeration. Hope, that everything will be better.

 

[ScottL4619]

I'm not sure if anyone is still monitoring this thread, but I have a quick question for anyone who is knowledgeable on Caulerpa. I first got some of this macro last week and prior to putting in my refuge, I did some research. I found the consensus to be lighting it 24/7. I would like to switch it to 18 on and 6 off as mentioned above with the 6 hours off right in the middle of high noon so to speak on my display tank lights. So, the question is: should I just drop from 24 on to 18 on, or change 1 hour per day/week? I am shortening the light cycle either way, and I know this can cause the caulerpa to think it is winter and go assexual. Any suggestions? My thought is to jump to 18 hours as a gradual change in light would probably signal changing seasons more so than a big jump.

 

[drinkhomebrew]

Is anyone still using this system? Anyone see any noteable long term results?

 

[mr.wilson]

<a href=showthread.php?s=&postid=11040783#post11040783 target=_blank>Originally posted</a> by ScottL4619
I'm not sure if anyone is still monitoring this thread, but I have a quick question for anyone who is knowledgeable on Caulerpa. I first got some of this macro last week and prior to putting in my refuge, I did some research. I found the consensus to be lighting it 24/7. I would like to switch it to 18 on and 6 off as mentioned above with the 6 hours off right in the middle of high noon so to speak on my display tank lights. So, the question is: should I just drop from 24 on to 18 on, or change 1 hour per day/week? I am shortening the light cycle either way, and I know this can cause the caulerpa to think it is winter and go assexual. Any suggestions? My thought is to jump to 18 hours as a gradual change in light would probably signal changing seasons more so than a big jump.

I think you could change it right away in one shot. A 24/7 photo-period gives the algae no schedule to start of with, so a change will not be measured as a season change. A gradual change will simulate a shortening season, but if it's only a few days, it will be just like a cloudy day.

The algae grown with a 24/7 photo-period has a constant die-off, so it doesn't need to crash as it ages. You get the same problems experienced with crashes. The first-in-first-out method suggested here assures that the algae culture stays young and healthy. Older algae from the bottom of the clump is collected to remove more bound nutrients and make room for new growth.

The important thing here is you need to adapt the way you keep the algae. You need to assure that the algae grows in shallow clumps, with little shadowing of the lower, older portions. You can achieve this by keeping up with weekly harvesting, or you can use the method I suggest in this thread, so the algae has no way of overgrowing itself.

 

[mr.wilson]

<a href=showthread.php?s=&postid=11041491#post11041491 target=_blank>Originally posted</a> by drinkhomebrew
Is anyone still using this system? Anyone see any noteable long term results?

It's hard to measure success in a reef tank, and even harder to attribute the source.

When a company is selling a product, or an end user is trying to justify the expense of buying one, they are quick to report success rates. I can report good success with this method, but I have also had similar success with other methods. I'm confident in recommending it.

I treat the method as a system, rather than one component. As mentioned previously in the thread, there are many aspects to the system.

1) Proper flow dynamics.

2) Right-sized flow from sump to display tank and back.

3) Zoned areas where biological filtration of various forms can be carried out to assimilate and dissimilate organics as in nature without residual nitrate.

4) A means of nutrient production.

5) A means of nutrient export.

6) Chemical filtration.

7) Preservation of probiotics and parameter stability through the exclusion of water changes.

I will post new pictures of the 220 gallon tank shown earlier in the thread in a few days.

 

[ooba]

Great thread, has helped a lot in not only planning my sump and refugium, but also in spawning more interest as i just bought and read Steve Tyree's book. And i will need to read it a second time.
A question, i think from the ease of maintenance, going barebottomed in the refugium zone of the sump would be the way to go, but would some of the organisms we are trying to cultivate (worms) thrive more easily in a sand bed, be it shallow or deep?
and second, just to clarify, you suggest tossing any 'bad guy' inverts into the refugium zone...is there any concern for these inverts preying on the sponges, tunicates, worms and other animals we are cultivating?
Thank you

 

[mr.wilson]

There appears to be ample shelter for worms in the duplex filter without the need for sand. They can move freely through the macro-algae, rock rubble substrate, and eggcrate structure. They have easy access to detritus in each of these zones, and the loose rubble is easier to navigate than sand.

I find that bristle worms prefer to live within the macro-algae, or perhaps they're just easier to spot there. Detritus is more abundant in the open areas than within the sand bed itself.

A deep sand bed would be a great addition to the duplex method, but it requires a deep area to work with. One that is hard to come by for most installations. The main purpose of the duplex method is to fit a lot of function into a small space. The area below a reef tank runs out of real estate quickly once you add plumbing, pumps, sumps, and miscellaneous gear. If you have a large sump room in an adjacent room or basement, then it would be wise to house each zone in its' own dedicated container. More space (depth) could be given to the benthic zone, and deep sand bed. The macro-algae zone could use a larger footprint, but the depth should remain shallow (4-6") for the reasons given earlier. This would be described as a "Naturalized, or Zoned System", rather than a "Duplex System".

The toxic nature of sponges makes them unpalatable to typical bad guy detrivores like starfish and crabs. I haven't noticed them parasitizing tunicates or worms either, but you would have to monitor each inmate closely for a while. They would be easier to remove from the duplex filter than from the display tank.

 

[snorvich]

What speed of water do you pass through the refugium part? (GPH)

 

[mr.wilson]

Flow to and from the sump isn't the crux of the system, but cycling 3 x the tank volume is the ideal ratio to aim for.

For some reason, the norm has climbed to 10 x the volume or greater. This causes drainage shortfalls, excess noise, micro-bubble formation and return to display, heat transfer, excess energy consumption, poor surface skimming and inefficient protein skimming.

The function of moving water to the sump is to fulfill the requirements of the protein skimmer and refugium. Most protein skimmers require about 3 x the volume of the tank for throughput, and refugia function better in a low flow environment.

Any flow in excess of the protein skimmers demand is counterproductive.

 

[snorvich]

Since I will be having a separate refugium, can I flow 3 times the tank volume to the skimmer in the sump and only ONE times the tank volume (325 gallons) to the refugium? Thanks.

 

[snorvich]

This is what I am planning. Any issues? Will be fed from the sump with an Eheim 1250 (300 gallons per hour). Thanks in advance.

 

[tasos]

Mr Wilson, which is the flow you would prefer for a 20G duplex refugium, presuming that most of it (aprox.70%) will pass through the macroalgae compartment leaving the rest slowly ''glide'' below to the filter feeder's zone!!
Will a refugium like that back up for a 120G total mixed reef system with live rock, 1-1,5 '' of sand on the display? Do I need to stay with the caulerpa or can I switch to chaetomorpha? I a bit worried about c.racemosa leaking dangerus substancies to the water especially for sps corals...
A note: white hard shelled worms seem to like the aprox. 500g/h flow of my sump, and like to occupie the glass of my skimmer compartment ,where is dark.....most sponges also don't hate enough flow,so why do we have to have relatively slow water flow to the cryptic zone?

 

[tasos]

Hello, maybe Mr Wilson is out of the forum these days.Anyone else?I want to procede with the project, but I am not convinced that the area within the eggcrate surfaces is bigger than the whole area behind and inside the rock, glass, sand surface in the rest of the aquarium,in order the eggcrate fauna being able to clear polution in the tank!Thank you!

 

[mr.wilson]

<a href=showthread.php?s=&postid=11080861#post11080861 target=_blank>Originally posted</a> by snorvich
Since I will be having a separate refugium, can I flow 3 times the tank volume to the skimmer in the sump and only ONE times the tank volume (325 gallons) to the refugium? Thanks.

By all mean, yes. You can direct the proper amount of floe to each zone as required. It's part of the idea that we are not limited to whatever our pump just happens to produce.

Unfortunately, the purpose of having a sump has slipped away for some. Many reef systems are designed to go through great effort in moving water to and from a sump, while making little effort to process the water in doing so. Useless protein skimmers, ineffective refugia, and misuse of chemical media make some sumps more of a liability than an asset.

I can't say I know the magic number for refugia flow, as it depends on what you're doing.
Sponges and other sessile (stationary) invertebrates need a constant supply of nutrients floating by, and some macro algae need good flow to remove detritus (particularly chaetomorpha and gracilaria). Zooplankton flourish in slow flow.

You also need to asses your detritus collecting practices. If you don't have a good mechanical prefilter, you should have a settling area, where the influent water is slow enough to allow detritus to settle in one, easy to harvest area. This area doubles as an influent zone for your protein skimmer, if you cannot plumb it directly to the display tank drain. The settling point can be cleaned manually or you can employ aiptasia anemones, colonial polyps (anthellia, xenia etc.), starfish, urchins, crabs and snails.

If some of your processed protein skimmer water is bypassing the refugium, make sure you do it with plumbing (add a tee and valve), and not a large glass bypass section. Sump designs that segregate the refugium to a small strip off to one side, decrease refugium efficiency and allow for wasted space.

Providing slow flow to the lower, Benthic zone, portion of the Duplex filter is simple, as the water from the protein skimmer zone will take the path of least resistance, across the top with only passive flow below the eggcrate platform. The relatively large size of the Duplex area creates slow pressure while maintaining high volume. High volume is rarely a problem, while excessive pressure can be problematic.

 

[mr.wilson]

<a href=showthread.php?s=&postid=11095174#post11095174 target=_blank>Originally posted</a> by tasos
Mr Wilson, which is the flow you would prefer for a 20G duplex refugium, presuming that most of it (aprox.70%) will pass through the macroalgae compartment leaving the rest slowly ''glide'' below to the filter feeder's zone!!
Will a refugium like that back up for a 120G total mixed reef system with live rock, 1-1,5 '' of sand on the display? Do I need to stay with the caulerpa or can I switch to chaetomorpha? I a bit worried about c.racemosa leaking dangerus substancies to the water especially for sps corals...
A note: white hard shelled worms seem to like the aprox. 500g/h flow of my sump, and like to occupie the glass of my skimmer compartment ,where is dark.....most sponges also don't hate enough flow,so why do we have to have relatively slow water flow to the cryptic zone?

I like to use the term "benthic zone" rather than "cryptic zone". Steve Tyree's term "cryptic zone" is specifically in reference to slow flow, dark areas on or near the substrate, and in some cases, on the undersides of rocks. The term "benthic zone" encompasses a variety of habitats that can be found in or near the substrates. This allows for some passive illumination and may include some fast moving water.

In the case of an overflow box, it can be deemed a benthic zone, as it isn't directly illuminated, but some light may reach it. The flow rate is clearly rapid in this zone as all of the water going to the sump must pass through a relatively small area. You may even get bubble introduction if your overflow is undersized or poorly designed. Hard tube worms, sponges, and squirts flourish in these areas. It's rich in concentrated nutrients and receives more food (nutrient import) than the display tank in some instances (careless feeding of floating foods).

The idea of having a Duplex filtration system is to provide a variety of environments so there is a suitable home for greater biodiversity. It's a "build it and they will come" approach. Wherever there is an opportunity in the the ecosystem, nature will provide life. Your overflow may be the most opportunistic area, so it will be populated first. The lower benthic zone is also slow to be populated as invertebrates must travel through a series of physical barriers (mechanical filters) in order to reach the zone. It's a good idea to directly seed the benthic zone or at least delete mechanical filtration for the first three months.

The biomass in your benthic zone(s) is an indication of nutrient levels. An overgrown benthic zone is a sign that you have the means to reduce (assimilate and dissimilate) organic compounds, but it's also a sign that you have a high need (high bioload).

You may choose to upgrade your protein skimmer performance, add more chemical media (carbon, polymeric absorption, ion exchange resin etc.), increase mechanical filtration, or increase macroalgae harvesting, if you feel that you have too many free nutrients.

A well established, naturalized system like this will act as a live food (zooplankton) farm for the display tank. At this point of maturity, you will be able to decrease nutrient import (feeding the tank). It will never be a fully self-sustaining ecosystem, but a balance can be achieved that will limit your input.

I wouldn't worry about the C. Racemosa. Chaetomorpha grows too slowly to be an effective exporter in my opinion. Every form of algae has some kind of toxic allelopathic agents. These toxins will not effect the display tank if algae is grown in a healthy environment, free of competition and threat to its' existence, such as over-crowding and interruptions in illumination. Some varieties, such as Caulerpa Prolifera have anti-bacterial agents that may benefit the display tank. Algae, invertebrates, and fish have a symbiotic relationship in nature. A similar balance can be reached in captive reefs.