Hmmmm....that's a new one to me.  I say have one for sure.  IMO if one says that something is "bad" without any facts to back the reasoning, there is no justification.

Pros:

1. The more water that you have in your system, the less forgiving a potential problem may be.

2. You have a place to have more sand and live rock to aide in the denitrification process.

3. You have a place to house algae (most people don't want in the main tank) which removed excess nutrients from the water column.

4. A breeding ground for pods (away from predators.)

5. Ability to run reverse lighting which helps in stabilizing pH during the night hours.

Cons:

1. It can be a pain getting one started and it costs a bit more money to set up.

2. Potential for more spillage if not set up right.

I have been running a refugium the whole time I've had a marine aquarium and I've never had an issue.  What is he saying is bad about having one?

SSpargur wrote: Pros: 1. The more water that you have in your system, the less forgiving a potential problem may be.

Since I know he meant "The more forgiving a potential problem may be."  I'll note it here.

There are many opinions on many subjects in this hobby.  Many things work perfectly for many different people.  Sean probably has a great system worked out for his tanks.  He must because his show tanks look great.  However, I bet you'd find if you took a poll that most members of WMAS use sumps and refugiums.  This is because they work great for most of us.  But sump/refugium are like plenum.  Some people swear by them, some people hate them.  What works well for you is the best choice, but for my money definately use a sump/RDP refugium.

I can't think of a reason to not have a sump.  Even a 10 gal sump on a 1,000 gal tank is beneficial.
It gives you an area to put a skimmer, or to put a bag of carbon, or to have your water top off, or whatever else.  Even if you don't make a refugium, and sump is still good to have.

Adam

pmpt wrote: But the plenum is up in the main tank, where its suppose to go.

I don't know about that. To resolve some of the issues that have occurred because of plenums, I have heard of people using plenums in their sump. That way, if you need to remove your plenum for any reason, it is easily removed without tearing apart your display. And you are still getting the benefits of a plenum. (Which are arguable anyway...)

Why not just use a DSB?

DSB = Deep Sand Bed

pmpt wrote: What is a DSB? I really need to learn all of these acroynms. Would you put sand in your sump, if you used the plenum down there?

DSB = Deep Sand Bed

Acronynms = see this thread http://www.utahreefs.com/forum/forum_posts.asp?TID=3622 - http://www.utahreefs.com/forum/forum_posts.asp?TID=3622

Sand in your sump?  No, in the refugium, you might suck sand in your pump!  However, my sump/refuguim is together and I have a suction hose in it just above the sand.

If you used the plenum down there?  Yes/No, see above.

The advantage of a plenum is to get more of the bacteria that convert Ammonia to Nitrite and Nitrite to Nitrate.  Those bacteria are fast growing and fast workers.  They can be found in the sand, rocks, and water.  So, just add more rocks to your refugium! 

I have talked to Shawn on many occassions, and he does have some very different opinions on how to set up a reef and what to use, he does not like refugiums, and he does like plenums, he also runs a big UV sterilizer,24/7.

Talking to him and many others showed me that there is no ONe right answer on how to setup a reef, but many correct answers. Experience, Patience, Knowledge, and a lot of spare cash doesnt hurt either. BTW he must no what he is doing because his show tank is the best looking around, every coral he has is huge and gorgeous in that tank.

A tank according to shawn would consist of a plenum with 3-4" of carribsea reef-floor special grade sand, a mix of tongan/fiji/(maybe) atlantic live rock, a berlin style sump with a skimmer, a big UV sterilizer and a canister filled with a mix of zeolite and activated carbon.  I think he's a bit flexible on the plenum vs. dsb aspect... either is ok, but he prefers a plenum.  I think he would say the most important piece of filtering equipment is a UV.  He's a big time UV fan.  His opinion on macro algae refugium is that the pH benefits of RDP are overblown and the hassles of keeping it going are not worth the benefits.

If you've not seen his store's display tank you should, it's the best looking LFS tank in the state, imo.  It just goes to show that there are more then one way to keep a reef tank.

Back to the orginal question...
Every reef tank needs a "filtration" method to remove/eliminate nitrogen and phosphorous wastes from the water column.  Nitrogen can be removed by denitrification occuring in a dsb or within live rock with the nitrogen gas produced just degassing out of the aquarium and into the atmosphere.  It can also be incorporated in algae growth and then removed from the system by harvesting the algae.  Protein skimming will also do it.  To a lesser extent nitrates can also be removed by adsorbtion on zeolites and activated carbon.  Water changes will also reduce nitrates.  Phosphates are a little bit different beast.  There is no export pathway similar to denitrification.  Phosphates must be removed via those other nitrogen export pathways... namely, protein skimming, zeolites and activated carbon and algae growth (and subsequent harvest).  I think part of Shawns success (on the phosphate front) is his use of zeolites and skimmer.  He has no other phosphate export mechanism.  Growing algae is not that difficult and it kills two birds (nitrogen and phosphorous export) with one stone.  But if you're more comfortable using some other method then have at it.  Refugium life is almost as interesting to observe as "normal" reef tank life.  That alone is worth the effort in my book.

Jon said

If you've not seen his store's display tank you should, it's the best looking LFS tank in the state, imo.  It just goes to show that there are more then one way to keep a reef tank.

I agree 100%, his tank is unbelievable

I think it is great Shawn replied to Mark.  I wish he would have posted here for all of us, because he is obviously experienced in the hobby and has viewpoints to share. 
I don't expect store owners to spend hours a day here or anything, but I think we can all agree that it would certainly help their businesses to make posts here on store specials and the like.

Adam

pmpt wrote: I do remember him saying that it could never be large enough to breed enough pods to feed your tank. Which is true.

I have a 25 gallon refugium (which I bought from PMPT ironically) for my 125 gallon tank it breeds pods like mad. I really fail to see his logic.

I bought the tank cheap from someone because they couldn't keep anything alive. I added a refugium and it brought the system to life. Not to mention that I didn't have enough pods to keep all my meat-eaters alive before. I never see a pod alive very long in my main tank, but all my fish (including a dragonette) are all fat and happy, so I figure they are just eating them as they arrive from the RF.

I shudder to see any tank without a RF now, as I wonder how they plan to keep nitrification going and PH balanced.

Working Great thanks! I set it up with lower water flow, a 4" DSB of Oolitic sand from Mark, and have a mixture of different Macro Algae.

I can testify that my Caulerpa went sexual after only a couple months. Mostly my fault because I was keeping the RF FULL of macro. I have since learned to harvest it when it's about 1/2 full. No problems since.

I also added multiple kinds of macro and have kept the caulerpa in check since that experience.

You JIPPED ME 5 Gallons?!?!?! j/k thanks for reminding me

pmpt wrote: So does that little tank, you are using as refugium really keep that big 125 up and going with live food? I know it couldn't be all of your feeding, but do you see a difference?

All I know is that Dragonettes are known for only eating live bugs, and mine is fat and happy. I never see him eat any food I feed the rest of the fish.

That being said, I also NEVER see a live bug in my main tank either, so I could probably do for a bigger RF, but as long as everyone is happy in the tank, I won't mess with it.

I should mention that I don't have any LR in my RF. How much does that matter? Would it help/hinder bug reproduction or just take up space for no reason? I've thought about taking some LR from the main tank, putting it in the RF for a while and then trading it back, in the hopes that I would take a bunch of pods up to the MT with it.  I would like to see at least SOME pods living and reproducing in the main tank too.

pmpt wrote: What do you mean you "Caulerpa went sexual"?

I believe this was one of the possible drawbacks that Shawn was talking about occurring after 5-10 years. If your don't have enough nutrients in the tank to support the Macro Algae, then it 'goes sexual' and essentially dies, dissolves, and sends it's seed off to a better place where more nutrients exists (or so it thinks).

The reason this is dangerous is because for some reason when some of your cauerpa goes sexual, it seems to notify all the other caulerpa to do the same thing, so all your macro can die off in a day. That can throw your tank chemistry off (macro no longer exporting), and cause a crash.

ummmm.....right Mark? (here I am talking like I know what I'm talking about, I just learned all this myself)

Well while there is definitely lots of routes to a successful reef tank I couldnt personanly imagine not having a sump for filtration and a refugium if space and fun dollars permitted it.  I avoided both for a while when I got into the hobby due to lack of knowledge but have slowly added them to all of my systems since first trying one.  In every case they have worked well for me although I realize that others "Milage may vary to one degree or another".  At the moment I think the Nano reef  and Live Rock Vat I have is the only systems with out one.  I have been extremely pleased with the results.

I think Sumps are a better filtration system than the many other options out thier.  I like the fact that I can keep it under the tank where maintenance is much easier.  I like the fact too that I can put all of the crap that distracts from my display down into the sump such as skimmers, heaters etc...

Refugiums...I couldnt imagine not having one on my tanks.  The only disadvantage to them I see is needed space and more money out  lay for set up.  But they can be set up fairly cheaply though.  Most have been set up with Rubbermaid Polyp tanks used for cattle troughs as they are so cheap, durable and easy to work with although the sizes are sometimes a PITA if you want to hide them under a tank.  The other refugiums were from old tanks I had laying around or scammed from prior projects (I keep a lot of reptiles too).  All of mine have DSB's, lots of live rock rubble (DIY Rock seeded with Live Rock) Mangroves and Chaeto macro-algae as a minimum.  Some of my refugiums also have Caleurpa(sp?), but just a little.

Other than some of my refugiums actually looking real nice, I like the fact that I have an endless supply of pods, pepermint shrimp.  I like the fact too that since using them my water has been much more stable, nitrates-phosphates low and no algae problems in the main displays unlike many!

Just my .02 cents worth.....

Patrick,

I would be willing to bet that you have a lot of pods in your main tank, if you take a look when the lights are off.  It's kind of like looking at one of those pictures where the image isn't readily apparent.  You have to stand and look for a few minutes, and all of a sudden you see one.  Then you see dozens.

From what I've read the reason why caulerpa goes sexual is not because it runs out of nutrients, but because it runs out of space.

Mark Peterson wrote: Yeah, Caulerpa has problems when nutrients are low, which can happen faily quickly in any tank.

If the caulerpa runs out of nutrients it would just stop growing and slowly die off.  Which usually only happens if you don't have a DSB, add little or no food to your tank, and have a large skimmer and other filtration.  Otherwise there is usually a constant stream of N and P. 

So what else would other marcoalgaes take out besides N and P that caulerpa does not?

I've had caulerpa racemosa peltada dissolve away twice on me.  The only commonality between the two cases, that I can see, is lack of nutrient input.  In both cases the flow through my refugium was greatly reduced due to snails plugging the line to the refugium.  In both cases the algae dissolved within hours (I don't really know how long the water flow was reduced before the event, I just know that I left the house for just a few hours and came back to a mess).  In the first case the algae was crowded but in the second it was not.  Since that time I've read many times that C. racemosa peltada is very prone to doing this... much more so then C. racemosa (grape) or even the other Caulerpas.

Mike Peletta subscribes to the notion that 24hr lighting is, at least partly, the reason why his macro's don't do this.  His reasoning has to do with the photosynthisis "dark reactions" not occuring which is where/when caulerpa's release toxic compounds and go into the reproductive cycle...  But I don't know.

No, not that I would blame on the algae.