Limitations of DSB's - Page 10

MJB · 04-11-2003, 08:56 PM

I agree that what you were saying was that metals weren't the issue.--MJB

Hermit · 04-12-2003, 12:38 AM

You think your confussed, Spanky. Try being the poor schmuck who spent his college career studying literature.

If I'm understanding all this correctly, we agree that DSB's are good for nitrogen removal, but bad as a sink for things that don't break down to nitrogen gas or CO2. Is that correct?

04-12-2003, 03:47 AM

I just wanted to say that whomever said that DSB's will not work in a nano is very wrong. The argument made was not enought surface to bio load ratio. That is very bass ackwards. In most cases there is a ratio three to four more times live sand in a nano as compared to a "large tank". If a DSB is really gonna work than it will be most efficient in a nano.

SPC · 04-12-2003, 06:29 AM

Quote:

Originally posted by Acoustic
I just wanted to say that whomever said that DSB's will not work in a nano is very wrong. The argument made was not enought surface to bio load ratio. That is very bass ackwards. In most cases there is a ratio three to four more times live sand in a nano as compared to a "large tank". If a DSB is really gonna work than it will be most efficient in a nano.

There is more to the argument Acoustic. Ron has also stated that (X) amount of sand is required in order to keep the diverse # of sand bed critters that are required for a DSB to function properly over time.
Steve

Casey · 04-12-2003, 06:40 AM

anyway you look at it guys we are going to have to replace the sand one day any way cause it will not function properly forever.

Spanky · 04-12-2003, 07:28 AM

Quote:

If I'm understanding all this correctly, we agree that DSB's are good for nitrogen removal, but bad as a sink for things that don't break down to nitrogen gas or CO2. Is that correct?

Correct a-mundo! and how well that works is going to depend on the actual composition and construction of your sand bed, how well it's maintained (critters too), the delicate balance of input and output, age, etc

One more time for old times sake - this is not nature. No where in nature do you have this concentration in such a confined space. This is a closed system and a screaming testimony to the adaptability and hardiness of these animals within certain parameters.

Geoff · 04-12-2003, 07:56 AM

OK, now that we are back on DSB's in a closed system. i want to ask this question again. i thought one of the benefits of having a DSB is that the DSB was able to help supply CA to the water column. the way i remember it was that the lower anoxic layers in the sand dropped the ph enough to cause some disolution of the sand itself, like a CO2 powered CA reactor. granted this is not a lot, but i think it is a benefit.

G~

cycler · 04-12-2003, 07:58 AM

spanky;My own dsb has been going for 14 years when does it quit?20 years 40?My tank has no filtration,has never been skimmed, so I presume I would know if the dsb stoped functioing.

Spanky · 04-12-2003, 08:04 AM

You guys are up already?

Geoff, you're right. It sure can.

William, You would know for sure. What animals are you keeping? Some are a lot more forgiving than others. I'd bet you're more particular about your husbandry too.

cyberchef · 04-12-2003, 09:47 AM

Quote:

Originally posted by Geoff
OK, now that we are back on DSB's in a closed system. i want to ask this question again. i thought one of the benefits of having a DSB is that the DSB was able to help supply CA to the water column. the way i remember it was that the lower anoxic layers in the sand dropped the ph enough to cause some disolution of the sand itself, like a CO2 powered CA reactor. granted this is not a lot, but i think it is a benefit.

G~

This is true, and supposedly it is even more true with a plenum. But due to the amount of calcium loving creatures most of us have in our closed systems, it is not able to meet the demand placed on it.

tdwyatt · 04-13-2003, 09:54 PM

Sorry, One more reference related to the actual ocean and the Carbonate sediments, just for those of you who have inquiring minds...

sediment maps...

aquaticsdeptleader · 04-14-2003, 11:38 AM

william you tank could demonstrate several things, some of which jerel mentioned but perhaps it also demonstrates that the particular animals you keep handel the gradual dejentritive effects that a long term dsb represent, on the other hand the possiblity certainly exists that the dsb setup in your manner is very succesful and its life span is of yet undetrmined, the issue i beleave is not about a dsb actouly being succeful only what limitations exist for this method of filtration. all methods have there limits skimming, live rock ect. unfortunatly i feel that many reefers believe that this is it a dsb is the be all end all the "perfect" filtration that once established can never fail. I beleave the pupose of this thread and others like it is dispell this notion. (of course Jerel if that is not what you had in mind please correct me)

jim

Tom Hulse · 04-20-2003, 03:56 PM

Hello, new guy here. I hope you don't mind having someone around that asks lots of questions.

Jerel, you seem to be saying that bacteria will continually take care of metals and that organics are the problem instead. I'm inclined to agree, but I hope you don't mind if I ask a few questions just to clear up some things for me:

Can bacteria colonies crash in our systems rereleasing metals in an OTS style event? From your first link:
"ecosystem is only temporary. ...Biomineralization will cease when microorganisms have metabolized all the metal available in the wreck and the ecosystem will then collapse. "
Is lack of food the only thing that can cause the bacteria to collapse? How about bacteria concentrations far in excess of nature combined with widely fluctuating ph? From your second link:
"...chemistry of the very thin layer of water trapped against the metal surface by the bacterial film can be different from that of the surrounding water. You can have a normal pH of about 8 outside the surface, but within the film and at the metal surface, the pH can be anywhere from 10 (very alkaline) down to 2 (very acidic)..."
And from this link (not great, but all I could find) our tanks may have bacteria in orders of magnitude greater than NSW. Can metals & bacteria accumulate infinitely without crashing?
Comments by anyone are appreciated. Thanks!
- Tom

Spanky · 04-23-2003, 06:27 PM

Tom,

Sorry, between work, life, and God's last head cold - I'm late! I didn't fall off the face of the earth, just felt that way.

>Jerel, you seem to be saying that bacteria will continually take care of metals and that organics are the problem instead.<

Not really. Not only can metals and organics build up in closed systems (rocks and DSBs) but some other things can too. I just didn't want everyone to forget about organics while they were worried about metals. Organics are the biggest problem in closed systems though.

>Can bacteria colonies crash in our systems rereleasing metals in an OTS style event?<

They sure can. Easiest example, stir a old DSB. Or lift a plenum.

>Is lack of food the only thing that can cause the bacteria to collapse?<

Or too much food.

>How about bacteria concentrations far in excess of nature combined with widely fluctuating ph?<

That's a great example, wish I had thought of it.

>And from this link (not great, but all I could find) our tanks may have bacteria in orders of magnitude greater than NSW.<

Yowsa, that's Richard's famous or infamous (shrug) study/test thing. But yes, closed systems will have not only magnitudes higher but also skewed numbers and types.

>Can metals & bacteria accumulate infinitely without crashing?<

Rephrase that to metals and organics. Bacteria are the third party. Bacteria will accumulate as long as there is food and new suitable habitat.
Metals and organics will accumulate as long as there are suitable storage sites. Rocks, sand beds, detritus in the sump, etc.

Tom Hulse · 04-25-2003, 09:32 PM

Thanks for the replys. Next question. If organics are the biggest problem in closed systems, can you help define them a little better? You touched on it before but it's still a relatively vague term. Could you give some examples?

Also, I don't mean to sound like I'm disagreeing, it's just that I'm a "why" guy: We all gave Ron a pretty hard time about his methods & lack of real evidence to support his hypothesis, but do we have anything better to support organics as a bigger factor in closed systems? Most of what I've seen says organics & metals CAN be a factor, but I haven't seen anything I've understood to be good evidence (greater than anecdotal) putting organics as our biggest nemesis in closed systems. Am I just not getting the point? Again, I think you're right on this, it's just the "why" thing. Thanks.
- Tom

ooppppssss!!!