Refugium confugium

[MarkD40]

I finally set up my 20 gallon refugium. My sole purpose is to grow cheato for nitrate removal, and gracilaria for my tangs. I already have a 75 gallon sump with a DSB for my 110 display. I figured that as long as I was moving water through the 20 why not put in a DSB and get some additional filtration. I was going to use KENT refugium substrate.

Before I did so I put a post on RC asking for opinions about DSB's in refugia. Basically I was told that a DSB in a 20 is worthless and that I should just go bare bottom. I did that and got my fuge running this past weekend.

Today I go to RC and read a post by "bertoni" with reference to romote DSB's in a bucket and how they are good at removing nitrate! How is that different from a 20 gallon tank? I am really confused to the point of serious frustration about this whole matter! Wouldn't a DSB in my refugium process some nitrate as well as release trace elements into the water column? Answers please. I just ordered my macro and I need to make any necessary changes soon.

Thanks!

 

[Travis L. Stevens]

Technically if you already have a DSB in the 110g, you have ample amounts of it already. If you feel like you need more, you can always add your algal scrubber in a refugium. If you still feel you want more, you can add a deep sandbed in the refugium. Say about 5" most likely. If you still feel that this isn't enough. Then definitely check into a RDSB. It is a bucket set aside that is VERY deep with sand. It doesn't provide the overall surface area like an in tank DSB, but it does provide large amounts of anaerobic area because of it's vast depth. Nothing like a good foot thick sand bed to kick that denitrification into gear.

One thing I always wanted to try was something like a refugium tower. where you get the giant bonus from a RDSB but still have enough room at the top to have an algal scrubber.

 

[Warnock316]

whats an algal scrubber? just macro mat or some thing else altogether?

 

[Warnock316]

I dont have a DSB in my refuge just bare bottom with some chunks of live rock for my pods with cheeto it doesn't really matter it is a nitrate sponge and a half, at least in mine.

 

[Travis L. Stevens]

<a href=showthread.php?s=&postid=7007904#post7007904 target=_blank>Originally posted</a> by Warnock316
whats an algal scrubber? just macro mat or some thing else altogether?

An Algal Scrubber is the use of a macro algae to scrub the excess nutrients out of the water. There are also Xenia Scrubbers, Sponge and Tunicate Scrubbers, and others.

 

[MarkD40]

Thanks (again) Travis. Mark

 

[Travis L. Stevens]

No problem :thumbsup:

 

[mr.wilson]

Although less real estate than your display tank, the 20 gallon refugium may perform better or at least differently.

The refugium will likely have a lower dissolved oxygen rate due to the slow, diffused flow. This will provide anoxic and hypoxic zones for denitrifying bacteria. Conversely, the display tank may have sifting and stirring creatures and high flow rates that would discourage anaerobic bacteria from flourishing.

The refugium area will also have greatly diffused light in the substrate as the macro algae will block it out. This too will aid in the development of denitrifying bacteria.

A remote DSB or RDSB, gives you more freedom to "feed" the bacteria with a sulphur, glucose or alcohol-based food source. DSB management practices and methodology will no doubt change in the future. A remote location will make it more adaptable to change.

 

[MarkD40]

Thanks Mr. Wilson but some follow-up questions:

1. The conventional wisdom seems to be that a refugium that is twice removed from the display tank (display-sump-refugium) will not get enough detritis to support copo/amphipods which I was hoping to introduce to wiggle around in the sand bed. I was told that I would have to feed phyto plankton regularly to keep them alive. When you go to reef-revolution to order copopods they state that the pods will live in the refridgerator for up to 3 months without food!

2. I have read on RC that breakdown of nitrate does not require anoxic conditions, and that live rock does little to break down nitrate.

3. When I set up my 110 gallon 7 years ago conventional wisdom was a sump with a plenum of 1" pvc with screen on top covered with an undergravel plate covered with screen and then topped with 4-5" of sand with powerheads on the UG risers. This is how my 75 gallon sump is set up. I have 0-0.5 nitrate. Now I learn that this is a nitrate factory and not a good system. I have measured the dissolved oxygen in my sump and it is saturated when corrected for salinity and temperature. Water collected from the UG riser has no measurable oxygen. IMO as the water is drawn through the sand aerobic bacteria breakdown the ammonia into nitrate using oxygen. As the water carries the nitrate into the deeper layers the oxygen is removed and facultative and then anaerobic bacteria convert the nitrate into nitrogen gas. The water then is pulled to the surface and ejected forcefully into the sump and is re-oxygenated.

It seems to me that this is much more efficient than a static DSB that functions by diffusion only, and allows the sand bed to process much more water in a shorter time. I have been told that this is incorrect by many on RC. What I am hearing is mainly opinions that are not backed up by fact as there have been no studies done that address the issue.

What are your thoghts?

Thanks, Mark

 

[Travis L. Stevens]

1) I'm not 100% sure about refridgeration of copepods. It might be manufacturer instructions that were posted. Reef Revolutions is in Tulsa, Oklahoma. I can ask them personally if you would like. You could also PM Keckles for a direct answer. Technically though, If your detritus is captured more in the sump, then you will have an easier time taking it out before it decomposes and releases nitrates back into the system. When you take it out, you will be taking out a lot of fauna, but you aren't going to deplete your system. Feeding phytoplankton on a regular basis is a big help in keeping a large population thriving and reproducing because, like all animals, their population density depends on their available food sources. If there isn't enough food, then there aren't very many. But, the actual feeding of phytoplankton technically is not necessary.

2) That is not true. The only way for nitrate to break down through bacterial means is in no to low oxygen areas that harbor anaerobic bacteria. There are other means of taking nitrates out of the system such as an algal scrubber and water changes. Live Rock does a ton to break down nitrates. How else would a bare bottom tank work. There is more anaerobic surface area inside a porous rock for denitrificating bacteria to live and grow then there is aerobic surface area for bacteria such as nitrobacter to grow.

3) This is true. And no one is saying that these "older" methods absolutely do not work. Some do when properly set up and maintained. Paul B has a tank that is 35 years old that runs an undergravel filter, and his tank is beautiful. Also, the amount of sand you have on your UG is also a big help. If you went with a two or three inch bed, you may have started to encounter problems. I believe this is where the misconception of an UG not working came in. People were scrimping and setting it up incorrectly. Technically, if you think about it, you just have a DSB with forced waterflow.

Basically, the facts are this about bacteria (excluding algae, etc). Fact: You need aerobic areas for the bacteria that break down Ammonia and Nitrite to grow. This can be done with live rock, tank walls, top layer of sand, bioballs, biowheels, etc. Anything that gets well oxygenated. Now, the tricky part is with denitrification. Fact: You need anaerobic areas for bacteria that break Nitrates down to grow. You can provide this with anything that provides no to extremely low levels of oxygen. Deep in the sand bed, deep in the rocks, etc. This biggest problem encountered is when there is little or no anaerobic areas presented in a filtration method. For example, bioballs are aerobic only areas. Once organics are broken down into nitrates, they concentrate there. Another problem with filtration methods are improper set up. For example, a plenum is a great option when done properly. All too often you see them either over powered with too much flow or not enough of a sand bed. This, in turn, allows too much oxygen through the filtration system.

In my OPINION ( ), I would shy away from one sided filtration such as biowheels, bioballs, etc for a long term filtration method. On the other hand, I highly recommend them for new tanks to speed up cycling because it provides the ample aerobic surface area to break ammonia and nitrites down. Then they should slowly removed in support of a long term filtration method. When setting up a long term filtration method, definitely do your research and make sure that it is two sided; providing aerobic and anaerobic areas. Find the ins and outs, the loop holes, the good, the bad, and the ugly of the prospective filtration method. Don't leave any stone unturned. Also, make sure there is easy clean up, and that it filters mechanically, chemically, and most importantly biologically.

 

[MarkD40]

TRAVIS, THANKS SO MUCH FOR YOUR INPUT! Finally someone who understands what I have been saying for weeks now. The minute anyone sees the words "undergravel filter" their mind snaps shut and they stop listening. I well understand that an UG with 2" of sand is good only for ammonia to nitrate. But I can't seem to get anyone to understand my feelings about a DSB over an UG filter being more efficient and logical than a static DSB. I understand that nitrate is converted to nitrogen gas in low to no oxygen zones, but I have been told several times in the past few weeks on RC that this is not necessarily true.

Biowheels and traditional UG filters are great for ammonia tonitrate but by themselves are incomplete biological filtration. LR and DSB's are there to finish the job. I feel that a DSB over UG does the complete job.

In your opinion could copopods life in a 20 gallon refugium with a DSB and no predators without feedings?

 

[Travis L. Stevens]

There are a few defaults of an undergravel filter and a plenum. With undergravel filters, you do get detritus clogged on top of the sand that then becomes a nutrients trap. A plenum is the same thing because it pushes water through the DSB and then you get detritus stuck on the bottom. In my, once again, opinion a static DSB is better because it is less likely to get clogged and if you have something that moves the sand such as starffish, snails, and fish, then it won't unbalance the system. For example, take a Diamond Watchman Goby in an UG tank with proper flow and a 6" sandbed. He then decides to dig a home under a rock and piles the sand up on one side of the tank 9" deep and on the other side, it's only about 3". He unbalanced and completely destroyed the purpose of a DSB/UG.

Copepods are going to do fine regardless of where you put them. I bet you have them in your sump right now and not even know it. I've said this time and time again. The true definition of a refugium is a place for delicate and easily preyed upon fauna and flora to grow and thrive without interruption. Now, you can add all sorts of stuff to it to help with your tanks filtration and double as a place for these refugees to hide. Most common examples are live rock, deep sand beds, and macro algae. Your tank already supports enough food for these refugees to grow. They just get eaten by your tank mates too quick to notice them. The addition of extra phytoplankton will make the population grow, because you are adding more food.

All in all, if you can maintain a system that provides the correct conditions for your inhabitants, it doesn't matter what filtration you choose. Two examples. One, a lagoonal system that is nutrient rich would probably need what most people would call a "poor" filter. Two, a reef drop off where waves break onto the reef where there is little nutrients you would probably need a "good" filter.

 

[MarkD40]

Travis, the info on copopods was from "Advanced Aquarium Online Magazine", "The Breeders Net, by Frank Marini.

..." Don't worry if the water goes clear. I have had some copepods in a 2 liter bottle with no phytoplankton added for almost 3 months. They might have lasted longer, had I added some phytoplankton. "

I was incorrect when I stated they were under refridgeration!
Thanks Again! Mark

 

[Travis L. Stevens]

Oh okay. I didn't think that sounded right. But still. The average aquarium (that's obviously done cycling ) will support "pod" life pretty much indefinitely as long as food is available. The additional food such as phytoplankton only makes their population density thicker.

 

[MarkD40]

Thank you Travis, your input is much appreciated! Mark

 

[charles6299]

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[mr.wilson]

First-off, these are just my observations and opinions. They are subject to revisal on a constant basis. The charm of this hobby is that even after all these years, we are still pioneers in a new frontier.

I have seen just about any kind of technology and methodology support a successful reef tank, and reef systems often work for a reason other than that which the designer intended. I service a tank that has an extremely efficient wet/dry filter and Red Sea Classic protein skimmer. The wet/dry filter is successful due to the large population of Aiptasia Anemones that moved in. The Red Sea skimmer doesn't skim much, but it's chock-full of serpulid worms (fan worms), tunicates (sea squirts), and sponges. It breaks my heart every time I clean the venturi valve and kill the benthic invertebrates that make it "work".

1) You have to decide why you want copepods, amphipods and micro-plankton in the first place? Is it to passively feed the display, or to assimilate excess nutrients?

If you are trying to foster live food production within the system, then you may consider feeding phytoplankton; however, by doing this you are importing nutrients and defeating the purpose of "naturalized" live food production, thus moving away from a balanced ecosystem.

If your main goal for copepod (etc.) production is to reduce (assimilate) excess nutrients, then you already have a food source in place. Pumps and filters damage (puree) the majority of live foods that manage to migrate to the display tank (via return lines). It is an effective, although passive, method of feeding the tank. If you were keen on raising large numbers of copepods and using them as a chief nutrient source, you would be better off farming them in a slow (or no) flow container that is well fed. Once again, this method is getting away from a naturalized, balanced system.

I think copepods (and the like) are a great tool for balancing a system. I'm sure they will have no problem finding a nutrient source in your refugium. Decaying algae releases it's catch of nitrate, phosphate, silicate and organic "fertilizer", back into the refugium. Copepods will grow to the exact population that is required providing they have no competition or predators. If they can't find a food source, then they are not necessary in your ecosystem.

2) There are biological methods of reducing nitrate without anaerobic zones, but denitrifying bacteria is not one of them. I believe that the centre of live rock is rich in denitrifying bacteria. They may not be a miracle cure for high nitrates, but they definitely play an important role in the reef ecosystem.

I have drilled many rocks to find burrowing urchins and worms within the rock. These creatures would not expend that much energy, unless there was a viable nutrient source within the rock. The bacteria that these worms dig for are obviously consuming something in order to exist. Nitrate is a logical nutrient source for them.

3) I don't know all of the details of the flow dynamics of your old system, but it's possible that the oxygen is consumed. I think it is more likely that there is a diffusion that leads to the lower dissolved oxygen levels in effluent water.

Public opinion bares little value in these matters. Undegravel systems (standard and reverse flow) can work very well. They can also be problematic, as they become mechanical filters. It is difficult to maintain a system where the levels of life are stable and not jeopardized by burrowing creatures or detritus removal practices (vacuuming and stirring). The regeneration time for bacterial film may exceed the amount of time that the substrate remains static. For this reason, I lean toward a static DSB.

This does not rule-out the UG system. All methodologies have their challenges, not all of which are tragic flaws. The same logic that would discount the use of UG filtration, would sanction the removal of protein skimmers due to their ability to remove trace elements, phytoplankton and zooplankton. UV irradiation and ozone would be outmoded due to its oxidization of live food, and algal turf scrubbers would be scrapped because of their allelopathic nature (competition toxins), and ability to leak their "catch" during respiration (at "night").

UG filters faded from existance due to missuse, and a lack of profit from theor sale. Who wants to sell $30.00 UG filter plates when acrylic wet/dry systems are $500.00 and up.

I like the idea of specialized (natural) zones. I don't think humans can replicate nature in one vessle. Your sump will afford you the ability to physically remove detrital build-up through siphoning, and POC (particulate organic carbon) removal by protein skimming.

Your (twice removed) refugium will remove residual detritus through benthic invertebrate assimilation and macro-algae export.

Your segregated DSB will remain "separate but equal".

 

[MarkD40]

Thank you mr. wilson for your input. I discovered RC 1 month ago and it is so great to be able to get answers to questions from others who are passionate about this hobby. I was "on my own" for 7 years with limited input from my lfs. My lfs is excellent but they are busy and it is hard to carry on a lengthy give and take discussions about things esoteric.

Conventional wisdom on the best way to set up a reef tank is constantly changing. I have noticed that there is a natural tendency among many that unless you are doing everything cutting edge that you will have poor results. I set my tank 7 years ago following the conventional wisdom of that time. After discovering RC I learned that my set-up is old school and I should make some changes. It is nice to have mr. wilson recognize the fact that some of the older systems still have merit and should not be disregarded out of hand.

That being said, I am now at the point where I am close to removing the risers from my UG filter and filling in the holes rather than completely removing the UG filter plate. Do you think this would be a good idea, or should I leave it alone? Thanks again for the really helpful input you have given me so far mr. wilson and Travis!

 

[MarkD40]

P.S. I do not want copopods as a food source for my fish. I was thinking that if I put in a DSB in my refugium they would be helpful to move the sand around. That being the case, do you think I should just leave my fuge bare bottomed with some LR, or put in a DSB. What is your feeling about KENT refugium sustrate?
Thanks, Mark

 

[mr.wilson]

If you have residual nitrate, nuisance algae, or any other performance issues with your system, you would be wise to cover the riser tubes and use it as a static plenum.

Refugiums with macro algae would benefit from a copepod cleaning crew. Rubble rock is a good choice for harbouring detrivore worms and copepods. Check out this rubble rock thread. http://www.reefcentral.com/forums/showthread.php?s=&threadid=634923

I like bare bottom for areas that are going to be frequently siphoned only. For this reason, I call it the OCD system. I use a zoned system with a skimmer area for fresh display water and aiptasia growth. The next zone is a shallow channel (5") of water moving quickly over Chaetomorpha & Gracilaria algae. Passive water flow reaches a lower "benthic" zone with an egg-crate strip plenum. Detritus migrates to the lower benthic level and is consumed by Detrivores. Benthic invertebrates are great water polishers, and are able to assimilate DOC & POC without significant residual chemicals or trace element depletion.

You can get a better look at the system that I use on the video at this site.
http://www.reefvideos.com/reefshowcase_03_content.html