plenum vs none? sand depth?

[crnaguy]

i am new to the hobby and i am setting up a 75 gal with a 40 gal sump. what are the latest thoughts on plenums? how deep a live sand bed in the main tank and the sump if no plenum? also, do you need to light the sump if there is a little live rock in it?

thanks for the help.

 

[ChaoticReefer]

crnaguy,
Deep sand beds are much more popular these days dued to that plenums can crash over time. Three inches is said to be the bare mininum for a DSB, deep enough so there is an oxygen free environment. This environment is needed for the bacteria that breaks down nitrates into nitrogen gas.

As for the sump, no, you don't need to light it. Only reason to light it is to grow macroalgae in which the "sump" will become a "refugium". The bacteria itself doesn't need any light.

Let me know if I can be a further help. Also, even though, you registered almost a month ago, let me welcome you into reefs.org community.

 

[Len]

I think plenums are out of favor, and rightfully so. Deep sand beds do essentially the same thing, and just as effectively. The gradient differences and anoxic zones will exists, with or without a plenum. So really, there is little point in installing this additional complexity. Some anecdotal reports claim of crashes over time for plenum tanks. But to be fair, system-wide crashes has been reported for all types of filtration methodologies, so I take these horror stories with a grain of salt (no pun intended).

Sandbeds can go anaerobic (condition required for denitrification) in as little as 2 inches of substrate, depending on sand particulate size, ambient oxygen levels, etc. 3-4" is a safe number to go by, and you may consider as deep as 6".

It sounds like your "sump" is more like a refugium since you intend to use sand and rocks in it. If you have the room, I recommend install a dedicated sump (where equipment such as skimmers and pumps are attached to) in additional to a dedicated refugium .... one that can be detached from the main system if need be. This flexibility will give you the best of both worlds and allow for servicing/"recharging" of the refugium without a headache. The sump can be unlit, and you can light the refugium to promote micro and macroalgae growth (good habitants for all sorts of microfauna).

 

[Ophiuchus]

I wouldn't say plenum or dsb are better or worse than eachother... it just depends on the system, IMO. The major difference, besides complexity of setup, however, is that a dsb absoulutely requires micro-fauna in order to operate. Without the little digging critters in it, no denitrification will occur- or at least very little compared to what it could process.
With a plenum, the only real factor in efficiency is proper setup and maintenance, depending upon the aquarist and not on little bugs :lol:
I personally use both, and have had 0-10ppm nitrates since setup.
On a side not, I remember reading an article somewhere regarding the natural reduction of phosphate in a plenum. Somehow the biological processes of the phosphate cycle took something away from the phosphate in the plenum (I think oxygen, but don't quote me) rendering the phosphate useless as a fuel souce for algae, etc.
If anyone's interested, I might be able to locate the article and give specifics.
Daniel

 

[reefsnreptiles1]

I vote for the DSB as well. I also feel that plenums are outdated and are just an accident waiting to happen (potential for crash).

Here is a good link where Dr. Ron Shimek explains why DSB is the better option:

http://reefcentral.com/forums/showthrea ... ht=plenums

 

[Anonymous]

http://reefs.org/phpBB2/viewtopic.php?t=17714

one of the many threads on the subject :wink:

 

[Anonymous]

http://www.thereeftank.com/forums/showt ... =Microcean

 

[Anonymous]

Both of those ideas are too risky, have a shallow sand bed and use a denitrator.

 

[Anonymous]

Both of those ideas are too risky, have a shallow sand bed and use a denitrator.

care to explain why? i'm curious..

 

[Anonymous]

Both of those ideas are too risky, have a shallow sand bed and use a denitrator.

care to explain why? i'm curious..

DSB's and Plenums are prone to crashing, so why bother.

 

[Anonymous]

:lol: I think we could say that about almost any aquatic endeavor. "Why bother." That's a good one.... :lol:

 

[Anonymous]

:lol: I think we could say that about almost any aquatic endeavor. "Why bother." That's a good one.... :lol:

You're just sour because you don't like me, no need to try to confuse newbies because of personal reasons.

 

[Anonymous]

DSB's and Plenums are prone to crashing, so why bother.

I don't really think either are 'prone' to crashing, and I think a dsb is less 'prone' than a plenum. What am I missing?

 

[Anonymous]

Righty: Nothing .

Also, no denitrator is necessary when dealing with shallow sandbeds.

Here is a thread for the inclined:
http://www.thereeftank.com/forums/showt ... adid=16741

Forgive my brevity, but this debate is starting to edge on boring.

 

[Anonymous]

Both of those ideas are too risky, have a shallow sand bed and use a denitrator.

care to explain why? i'm curious..

DSB's and Plenums are prone to crashing, so why bother.

well, i'm still waiting for the explanation-any studies, numbers, experiments to explain your contention?

i have never seen a dsb, whether 3" or 8" crash- and the majority of anecdotal evidence seems to indivate that they don't-ime

methinks i'll take a poll...

 

[Anonymous]

Both of those ideas are too risky, have a shallow sand bed and use a denitrator.

care to explain why? i'm curious..

DSB's and Plenums are prone to crashing, so why bother.

well, i'm still waiting for the explanation-any studies, numbers, experiments to explain your contention?

i have never seen a dsb, whether 3" or 8" crash- and the majority of anecdotal evidence seems to indivate that they don't-ime

methinks i'll take a poll...

Anecdotal evidence I have heard indicates that DSBs are prone to crashing, I have to evidence to back it up but I wouldn't take the risk on my tank when there is an easier solution.