Whats Wrong With A Wet/Dry?

[mikey98]

I just read Joe DeSantis's post and a few people said to get rid of the wet/dry. It was bad. Why? What is wrong with them? I have one and I was wondering if I should change my setup. I thought Wet/Dry was good. That’s why I bought one. If they are I could have made a plane old sump for a lot less. Also what would be the point of a sump if you don't have the Wet/Dry part? It then would be just a place to put some heaters, carbon, and a skimmer. Please enlighten me on why Wet/Dry is bad.

Thanks,

Michael

 

[tazdevil]

They are very efficient in producing nitrate. That's why they're not recommended for reefs.

 

[mikey98]

They are very efficient in producing nitrate.

Why are nitrates bad? I know I should know this but I am new and still reading and learning.

Thanks

 

[Anonymous]

Nitrates are not as deadly as Nitrite or Ammonia, but elevated nitrates are not found on the reef so we don't want them in our reefs either. When high enough they will stress some of the inverts and fish (although there is some thought that mildly elevated nitrates may actually be food for some inverts, so it isn't totally cut and dried).

The most sinister feature of high nitrates, though, is that it is a splendid fertilizer for nuisance algae.

 

[ReefLion]

Nitrates are poisonous in high concentrations, and in a reef system it's best to keep them as low as possible (with a few exceptions that I won't mention).

Wet/dry filters convert ammonia to nitrite and then nitrite to nitrate. That's what they are designed to do. The problem is that they also collect detritus that ends up decomposing and turning into nitrate, which really increases the nitrate load compared to not having one at all. They also contain no anaerobic zones, so they cannot get rid of the nitrate.

In a system with just live rock and live sand, detritus is not trapped in the wet/dry but rather gets consumed by creatures. The live rock and live sand bed, if deep enough, will convert the nitrate to free nitrogen gas, which evaporates from the tank.

Tim

 

[mikey98]

anaerobic zones

What are these?

So, a wet dry does a good job of eliminating ammonia and nitrite, but because they eventually convert it all to nitrate, and the debris they trap turns to nitrate, it can sky rocket to dangerous levels. And high nitrate levels can cause excessive algae growth. Right?

 

[SPC]

anaerobic zones


What are these?

-Zones with almost zero oxygen. The bacteria that convert Nitrite to nitrate require these low oxygen environements to survive. These zones can be found in a deep sand bed and deep inside live rock.

So, a wet dry does a good job of eliminating ammonia and nitrite, but because they eventually convert it all to nitrate, and the debris they trap turns to nitrate, it can sky rocket to dangerous levels. And high nitrate levels can cause excessive algae growth. Right?

-Correct
Steve

 

[ReefLion]

What Steve said.

Tim

 

[ReefLion]

I would also add, as others noted, that high nitrate can stress fish and inverts and ultimately cause disease or death. In some tanks this might happen before you really even see significant nuisance algae.

Tim

 

[tazdevil]

SPC posted:

Zones with almost zero oxygen. The bacteria that convert Nitrite to nitrate require these low oxygen environements to survive. These zones can be found in a deep sand bed and deep inside live rock.

I think he really ment to say, the nitrate is converted to free nitrogen gas, which is then eliminated. Ammonia to nitrite, and nitrite to nitrate occur in the high oxygen locations- that's what a wet-dry is, a high oxygen factory for eliminating ammonia/nitrite. If you use a w/d, you have to export the nitrates in some way. Most likely, this will be with partial water changes. However, with the advent of deep sand beds (dsb's), this nitrate removal occurs naturally, which is what we strive for. A natural method of filtration is more reliable than an artificial one.

 

[suckair]

heh,

Taz I was wondering how many posts would go by before someone picked up on that

 

[SPC]

Posted by Taz:

I think he really ment to say, the nitrate is converted to free nitrogen gas, which is then eliminated. Ammonia to nitrite, and nitrite to nitrate occur in the high oxygen locations- that's what a wet-dry is, a high oxygen factory for eliminating ammonia/nitrite

- , thanks Taz.
Steve

 

[danmhippo]

Very nice guys, Ditto to all of above.

Just want to say this. There is nothing wrong about Wet/Dry. They are very efficient in doing what they were designed to do.........oxidizing ammonia into nitrite and nitrate. The end result of W/D is nitrate.

Where as end result of system utilizing Deep Sand Bed, Plenum, or heavily planted macro algae refugium, or combinations of either is nitrogen gas. The nitrogen cycle in these systems does not stop at nitrate, but nitrate will be broken down further into nitrogen gas.

 

[DBM]

[Where as end result of system utilizing Deep Sand Bed, Plenum, or heavily planted macro algae refugium, or combinations of either is nitrogen gas. The nitrogen cycle in these systems does not stop at nitrate, but nitrate will be broken down further into nitrogen gas.]

I'm not 100% sure this is correct. My education and employment history is in aquaculture so the ammonium-nitrite-nitrate thing has been drilled into my head. Advanced koi pond people have been switching to trickle towers to LOWER nitrate. Yes, that's what I said, lower nitrate - and you can imagine the high biomass in a koi pond.

The explanation I've read is that the ammonium and/or nitrite are converted to nitrogen gas before it's converted to nitrate. Wish I could find the stupid link so I could direct you to it - then everyone could read from some people who appear to really know what they're writing about concerning the nitrogen cycle.

It has got me thoroughly confused, and I'll have to read up on it because it doesn't explain our experiences as reefers. Anyone familiar with this or have any comments?[/quote]

 

[tazdevil]

Koi ponds usually have live plants in them as well, I believe this would help reduce or eliminate nitrate. I do believe they would want some nitrate present to act as a natural fertilizer for those plants. In a reef tank- especially an SPS one, nitrate becomes a problem as it can cause algae blooms, choking out the SPS colonies. Also, Koi, would not be very susceptible to even high levels of nitrate, as they are a member of the carp family. Read that as being very hard to kill.


Many marine biologist have stated the trickle towers are nitrate producers, which, as long as you export it with some other method, isn't a problem. The dsb/plenum method of exportation came into being as people realized with this method, you can effectively eliminate nitrate, utilizing a natural method, which does not rely on high tech (and $$$$) methods to do this.

 

[wombat1]

Also what would be the point of a sump if you don't have the Wet/Dry part?

Seems like no one addressed this, so I will. A sump provides greater total water volume, which increases stability. If it contains a little live rock, it also provides a place for various critters to reproduce without being preyed upon by fish. These then feed your corals and fish continuously. A sump is useful for storing stuff, but more importantly as a way of skimming the surface water of the main tank. In a tank without an overflow, organics tend to concentrate at the surface and make an oily film. This film inhibits the tendency for oxygen to dissolve into the water and carbon dioxide to escape to the atmosphere--two things that you want to happen. This is why you typically see reef tanks with powerheads pointed at an angle towards the surface to violently stir up the water and promote gas exchange. An overflow plumbed to a sump and skimmer is the most efficient way to remove this film. BTW it's not really necessary to have a bona fide sump as in a tank under the main tank to accomplish this. Lots of hang on the back skimmers can do it just as well.
DBM wrote:

The explanation I've read is that the ammonium and/or nitrite are converted to nitrogen gas before it's converted to nitrate.

I think the original post was a typo. The cycle is ammonium--nitrite--nitrate--nitrogen gas.

 

[fishfarmer]

QUESTION - If wet/dry's are efficient at converting wastes to nitrates and nitrates are utilized by plants, wouldn't it cheaper to raise macroalgaes in an area after the wet/dry part instead of spending the money on sand, sand critters, etc. involved in utilizing a DSB as filtration?

 

[tazdevil]

Fishfarmer- good point. However, that depends on how much the wet/dry vs dsb costs are. Also, you are relying on a much more artificial means of waste handling. This was one of the pushes for the dsb's, they are natural, not as reliant on pumps to perform the task (in case of power failure, they don't crash as quickly as a w/d that dries out).

All in all, if you know the positives and negatives of every method, and how to deal with them, any filtration method can work.

 

[sub2hour]

Fish farmer has presented a new method not often discussed. I am setting up a tank and already have a wet/dry from yrs ago. I am reluctant to put 4-6 inches of sand in my tank because a) it looks nasty after awhile, 2) it takes up all the space 3) it increases the weight load of the tank substantially and 4) involves higher costs since I already have the wet/dry. When I bought the tank yrs ago LSB's were not the norm. I would prefer to use the wet dry in combination with a macro alge refugium to clear the nitrates. Has anyone had success doing this? I plan to have a decent load on the tank as well. I imagine I will have to perform some water changes as well, which is ok.

Dan

 

[fishfarmer]

depends on how much the wet/dry vs dsb costs are.

O.K. let's say you own the wet/dry already or have a bunch of bioballs in the closet and a beater tank for a sump.

How much does a deep sand bed, properly seeded cost? My 120 gal had 300 lbs of SOUTHDOWN(not available in all areas :wink: ).

300 lbs Southdown sand = $30.
Let's say LFS sand is $25 per 50 lbs = $150 8O just for sand, probably more though.

SEEDING sand bed with 5lbs LS = $11.25

DSB advocates recommend reseeding with critters yearly 8O so this may cost in the long run.

Snails to turn sandbed =?$, don't have any in the 120 bed, but plan on some on the 55 bed.

First year sandbed costs(Cheapo model)+gas to get the stuff = $50

in case of power failure, they don't crash as quickly as a w/d that dries out.

Good point. But I think both would be in jeopardy depending on how heavy the system is stocked. I think all tanks should have a backup system for main and sump and you could easily rig a small powerhead in sump to keep wet/dry and macroalgae stable just like you would do for the main tank with it's LIVE sandbed, right :wink: .

The natural vs. artifical argument(YAWN), sure I like the natural way, but I've yet to unhook my skimmer and toss my carbon.....and I STILL have a bunch of blue balls taking up space in my closet.

I know one CON of the W/D is the collection of detritus on the balls requiring occasional rinsing. I'm not sure on how frequent for cleaning. Once a year?

One con I see for a DSB, is that they are a PITA to move. I think if you aren't moving for a while DSB's are fine, but unless your tank is 55 gal or smaller you're probably going to tear the bed apart to move (I know some of you have done it with bigger tanks, but it's still a PITA).

Another con I've heard about DSB is that they take a while to fully establish, 12 to 18 months. But patience is the key to reefkeeping.

I would think raising macroalgae past the W/D would be pretty cheap.

Sprig of LFS weed=$8(preferably free)

Some sort of light/fixture=$30

Electricity=pennies a month