Tank - Refugium Substrate dilema/setup

[sleeman]

I am about 2 weeks away from setting up a 75 gal with 33 gal sump/refugium And am looking for opinions on what to do with regards to sand beds. I am leaning towards about an inch of sand in the main tank, with a DSB (5 inches or so of sugar sized) in the refugium. Would you use a plenum, or just go with a pile of sand in the refugium? Would you grow algae (if so what type) or mangroves?
I am also looking for more info on mangroves as well. If you have seen/read any please point me to them.
Thanks for the help.

Cheers,

Al

[sleeman]

Come on Folks,
You can't tell me of 50 people that have read this, not one person has an opinion on this?

Al

[LostMind]

nothing I have read about the plenum setup tells me it is better then just dumping the sand in the tank without a plenum.

as for mangroves, everything I have read says they are good, but slow growing, so nutrient export is low, and they are a little demanding in terms of care. most people use caulerpa in a refuge, but I have heard there are other good algaes to use, like gracilaria and sargassum. Dunno how to spell them, and I havent seen these algae's for sale anywhere, but there you go :)

and, I have no direct experience with the plenums or the mangroves - just making a statement based on the books I've read... maybe my reply gets this topic moving for you :)

[Bob I]

If I reply maybe someone else will show up to argue :rolleyes: . I have recently read half the posts on sanbeds on RC It seems the originator of all our sandbeds (Dr. Ron) is now all over the place when it comes to sandbeds. When I originally started sandbeds, the idea was for the deeper anaerobic areas of the sandbed would grow anaerobic bacteria, which would convert Nitrate to free Nitrogen. All you would need were some critters to stir the sandbed to prevent concretion. Using that methodology a remote sandbed like you suggest would be ideal.
Now, however, DR. Ron has changed tacks again and again. Today he says that method will not work because the sandbed needs to be populated with a great variety of critters. These critters need to be fed and you have to get new ones every so often. So now he says a remote sandbed can't work. :eek:
Now IMO since we can't get these critters here in Alberta anyway, I would go with the remote sandbed as you suggested. This way you are taking care of Nitrate conversion, which is really all we want to do anyway IMO..
Sorry for the long windedness :mrgreen:

[Jack]

1" in the tank is good and 4" in your refugium should be more than enough. :mrgreen:

[LostMind]

having the deeper sandbed remotely would make it easier to remove *IF* it was the cause of some future problems...

[mnoll406]

I have had 2 tanks with refuges. 1 with 1-2" of the sugar sand, and the other refuge with 4" of sugar sand. Both have become hair algae producers. I would try Bob Goemans Plenum method if I were to do it again.

Mike

[BCOrchidGuy]

Recent articles suggest 2 inches of sandbed does as much for denitrification as any deeper. The 2 inch also becomes completely populated with critters. I'm building my refugium and I'll be sticking with 2 inhces. From what I read though a plenum is a good system if you live in an area that has frequent power outages. I don't understand the theory behind that though.

Doug

[StirCrazy]

I would go with a inch in your main tank and 2 to 4" in your refuge. I think it would be more benifit you have rubble rock and such in your refuge rather than algae as there is no fool proof way of preventing algae from spreading to your main tank. but if you are ok with this then fill your boots :mrgreen: . Personaly I will never again prouposly introduce algae to any system I own :rolleyes:

Steve

[Bob I]

Recent articles suggest 2 inches of sandbed does as much for denitrification as any deeper. The 2 inch also becomes completely populated with critters. I'm building my refugium and I'll be sticking with 2 inhces. From what I read though a plenum is a good system if you live in an area that has frequent power outages. I don't understand the theory behind that though.

Doug

Could you point me towards those articles please. :question: :question:

[BCOrchidGuy]

Bob, The 2004 issue of Marine fish and Reef magazine has an excellent article on sand beds by Richard Harker. There are about 23 references. The basic point of the article is that with our overly simplistic understanding of sand bed denitrification processes we've made the mistake of thinking we need DSBs but we can have anoxic and suboxic microzones with in the top layer of sand. "Large areas of the sediment surface are suboxic, especiall at night, and that anoxia predominates at depths greather than about 1cm."(King 1990) "Denitrification is most likely to occur close to where nitrification takes place, and this occurs at the surface of the sand. "As much as 70 to 90 percent of the overall denitrification was located at the 1-3 cm depth"(Andersen, 1984). It turns out that an anaerobic habitat can be as small as 1mm, that aerobic and anaerobic habitat essentially coexist, and that as little as 0.08mm distance is sufficient for nitrification and denitrification to take place simultaneously (Fenchel, 1995).

The article goes on, it's rather interesting.

Doug

[Stretch]

I tend too believe that article, As my 1inch sand bed has plenty of gas bubbles in the sand bed. Of Course I do have a 3.5 inch bed in my 15g Fuge. I thought I'd share

http://members.shaw.ca/jessehamel/bubbles.jpg