DSB Heresy

[nameless]

IDR, I must have missed something. Why did you start dosing alchohol and sulphur?

 

[ldrhawke]

These are two approaches to running a nitrate reactor. Randy does a much better job of explaining.....


Randy's article:

http://www.advancedaquarist.com/issues/august2003/chem.htm

._ Use a carbon-driven denitrator._ There are a variety of different commercial systems available, none of which are especially popular in the United States at this time._ However, they can do a good job of removing nitrate and some aquarists quite like them.


In one of these types of systems, a carbon source is added to a portion of tank water in a low oxygen environment._ In many cases, the carbon source is methanol._ The methanol is mixed with aquarium water in a controlled situation (such as fluid pumped through a coil) and the methanol is consumed by bacteria that use nitrate as an electron acceptor instead of oxygen:


12 NO3- + 10 CH3OH + 12 H+_ à 10 CO2 + 6 N2 + 26 H2O


The end result is that nitrate is removed from the aquarium._ The typical drawback to such a system is the need for careful control over the conditions, and the consequent complexity that often accompanies such a reactor.


7._ Use a sulfur denitrator._ In_ these systems, bacteria use elemental sulfur and produce N2 from it and nitrate according the following equation (or something similar):


2 H2O + 5 S + 6 NO3- __à 3 N2 + 5 SO4-- + 4 H+

It has also been suggested to pass the effluent of such a reactor through a bed of aragonite to use the acid (H+) produced to dissolve the calcium carbonate, and thereby provide calcium and alkalinity to the aquarium.


While that is a fine idea, it doesnââ"šÂ¬Ã¢"žÂ¢t add much calcium and alkalinity to most aquaria.


To estimate the magnitude of the effect, we start with a liberal estimate of how much nitrate might be removed. Say 10 ppm of nitrate per week.

10 ppm nitrate = 0.16 mmole/L of nitrate

Since 4 moles of H+ are produced for every 6 moles of nitrate consumed, this will produce

0.107 mmoles/L of H+ per week


How much calcium this could produce?
Assume that it takes one proton to dissolve one calcium carbonate:

CaCO3 + H+ ßà Ca++ + HCO3-

Clearly, this is a substantial overestimate because much of the acid will be used up driving the pH down to the point where CaCO3 can even begin to dissolve. Consequently, we have an upside limit of

0.107 mmoles of Ca++ per week

since calcium weighs 40 mg/mmol, that's

4.3 ppm Ca++ per week.

For comparison, an aquarist adding 2% of the tank volume in saturated limewater daily is adding on the order of 16 ppm of calcium per day._ Consequently, this method may not be especially useful for maintaining calcium and alkalinity levels._ On the other hand, the acid produced will have a long term lowering effect on the alkalinity, so if you use it, watch the alkalinity.

 

[ldrhawke]

Additional comment.....

I was not getting full de-nitrification at the rate I was wasting through the CPW. This was an approach that was easy to implement and operate to obtain complete de-nitrification and not have to worry about and try to tune in the CPW drainage.

As I noted, CPW was obviously reducing nitrates through the DSB, but not 100%. Rather than recycle any nitrates back into the tank, caused by the high flow through the DSB or try to control and monitor flow, I opted to add a de-nitrification coil and reactor to assure of 100% reduction on a single pass at full flow. The alcohol is to feed the de-nitrifying bacteria. The sulphur balls will replace the need for alcohol feed.

I can test and sample before and after the reactor. I am hoping to find that over time, as the DSB stabilizes and adjusts to the CPW flow rate, full de-nitrification may start to take place in the DSB. If that happens, the coil/reactor is simply a belt and suspenders approach. It will not be doing much of anything since it won't be fed any nitrates. In the mean time this was a simple solution and experiment, and I wanted to better understand how de-nitrification can be improved upon in a reef system.

 

[ldrhawke]

Recently someone asked Dr. Ron what he thought of CPW. His response was,

This idea has been around for years. I can't see any merit to it at all.

Let me quote one of the more vocal advocates and experts on conventional DSB, and in great part the basis of the logic and research data behind the need for CPW.

This a quiz, who said this?

I have spent much of the last couple of years taking an indirect look at what happens in reef tanks with regard to various chemical constituents , primarily the toxic heavy metals, referred to in the hobby as ââ"šÂ¬Ã…"œtrace elements.ââ"šÂ¬Ã‚ Some of these materials are biologically necessary, but none has been ever shown to have any benefits at concentrations above those found in natural sea water. Indeed, most of them have been shown to be both acutely and chronically toxic at even slightly higher concentrations (see, for example, the discussion in Shimek, 2002d and these references: Alutoin, et al., 2001; Breitburg, et al. 1999; Goh, and Chou, 1992; Heyward, 1988; Negri, and Heyward, 2001; Reichelt-Brushett and Harrison, 1999). Those studies of documented toxicity notwithstanding, I have found that many of these chemicals have exceptionally high concentrations in the liquid medium of reef aquaria, as well as within the food we add to the systems..............................

In natural situations, heavy metal pollution typically results in the deposition of metals in the sulfide-rich anoxic layers deep in the sediments. It is likely that a similar deposition pattern occurs in deep sand beds. Consequently, the anoxic areas of the deep sand bed would be the place where tank waters would be detoxified. Water is slowly moved through these areas by the cumulative motions of the animals in the upper layers of the sand beds. This slow percolation of water results in these areas accumulating organic materials. The bacterial utilization of this organic material results in the elimination of oxygen in the deeper sediments. This, in turn, facilitates the removal of metals from solution. However, the accumulation of organic material in these sediments also results in these anoxic sediment layers getting thicker with time. If this occurs, the level where free oxygen occurs becomes shallower. Most animals cannot tolerate anoxic conditions, and will not penetrate those layers. This chain of events leads to a positive feedback loop, working over extended periods. As organic material builds up in tanks, the anoxic layers become deeper forcing the animals into shallower sediment layers. As this occurs, the animals can pump less water through the deep layers. This reduction in pumping facilitates the increase in thickness of these anoxic layers seen in highly polluted areas ââ"šÂ¬Ã¢â‚¬Å“ or in old reef tanks. In severely polluted situations in natural ecosystems, the anaerobic sediments may actually start at the sediment-water interface (Rosenberg, 1976). In aquaria, a situation such as this is very unlikely; the system will likely crash before it occurs.


It is tempting to suggest that the solution to this quandary would be simply to vacuum the sediments of all organic materials. However, such vacuuming would destroy the functionality of the sand bed as far as its beneficial aspects of excess nutrient processing and feeding the reef are concerned. However, as an alternative to breaking the tank and sand bed completely down, a thorough vacuuming of the sediment followed by re-inoculation of the sediment fauna must be considered as a viable alternative. It is important to note, however, that such vacuuming might not remove much in the way of precipitated metals. Rather, it would be a way to keep the organic loads from becoming extreme. It may also drastically affect pH, redox, oxygen levels and release lots of rather unpleasant anaerobes into the water column.


Alternatively, maintenance of a highly diverse and densely populated sand bed will help utilize much or all of this excess organic material and thus prevent the accumulation of excess organic material. Using this method of sand bed maintenance requires careful monitoring of the sand bed, and period replenishment of the faunal diversity.


Likewise, changes in the overall tank pH cycle may result in brief transient periods of acidic sediment conditions. During these periods, many of the bound heavy metals may become soluble. This would result in transient exposures to these metals. As heavy metal poisoning is commonly cumulative, the final lethal effects of such brief periods of toxicity may be seen only after several months or years.

Guess who...:rollface:

 

[LakesPookie]

i'll guess that was DR. Ron

 

[LakesPookie]

or was that randy?

 

[wasp]

I'll play
I don't really know,
but I'll guess Bomber?

First paragraph sounds like something "The Doc" would have said, but then moves on and sounds like something a well known "Doc" critic would have said.

 

[gregt]

I'll say this. You guys are nothing if not persistant. LOL

 

[ldrhawke]

I'll say this. You guys are nothing if not persistant. LOL

GregT,

I'm assuming your comment is based on our continuing down the path of trying to improve on DSB and not simply converting to BB?

First let me say I enjoyed you Web Site...great info and alot of good work. Also, let me state it has become obvious over the last year that a good reef keeper can make any reef keeping system. Some systems are just more work and less forgiving than others.

But, I do have a question and it is not meant to start a war of DSB against BB. It looks like you are going through high priced skimmers like and the prevervial hot knife in butter trying to find a good one. I have yet to hear any BB advocates, that have converted to plastic bottoms, talk about or give reports on water quality since they have converted. They seems to spend most of their time knocking anyone stupid enough to use a DSB and not convert to BB.

I can only assume, that your looking for a bigger and better skimmer, that nitrates continue to be an issue with plastic bottom reef tanks. Am I wrong?

 

[gregt]

You couldn't be more wrong.

First off, I've had 0 nitrates in any of my BB tanks. I use no chemicals and do "normal" water changes to accomplish this. It just doesn't get any easier than BB. I don't talk about it because, for me, it's a given. I wouldn't be using the system if it didn't work.

And secondly, I've had three systems in the last 5 years and three skimmers. I've upgraded skimmers because I've upgraded my systems.

It's very important that you size your equipment correctly. The Euroreef CS6-2 I was using on my 180 was a little undersized, it certainly wasn't going to work on my 400 gallon tank now was it?

And third, my only concern about DSB's is the vast amount of incorrect and misleading information being presented on their behalf. I have no problems with people that choose a DSB as their method. Heck, I still help people in my reef club design tanks around them if that's the way they want to go. I do have a problem when people present DSB's as a simple solution that has no downside. They aren't.

Your post is very elegant and clever but factually way off base.

I did not post here to disparage. I honestly commend you for your persistence. I still don't understand WHY you want to keep poop as a pet, but I don't understand why a blind guy feels the need to climb mount Everest, either.

You have my admiration for your attempts to find different solution. I'm sorry if my post conveyed any other message.

 

[Bomber]

I have yet to hear any BB advocates, that have converted to plastic bottoms, talk about or give reports on water quality since they have converted. They seems to spend most of their time knocking anyone stupid enough to use a DSB and not convert to BB.

I can only assume, that your looking for a bigger and better skimmer, that nitrates continue to be an issue with plastic bottom reef tanks. Am I wrong?

That's because water quality is no longer a issue.

I guess you just missed all the posts where we posted 0 nitrates. If you remove the source of the nitrates (detritus and bacterial detritus) you won't have them.

 

[ldrhawke]

You couldn't be more wrong.

First off, I've had 0 nitrates in any of my BB tanks. I use no chemicals and do "normal" water changes to accomplish this. It just doesn't get any easier than BB. I don't talk about it because, for me, it's a given. I wouldn't be using the system if it didn't work.

And secondly, I've had three systems in the last 5 years and three skimmers. I've upgraded skimmers because I've upgraded my systems.

It's very important that you size your equipment correctly. The Euroreef CS6-2 I was using on my 180 was a little undersized, it certainly wasn't going to work on my 400 gallon tank now was it?

And third, my only concern about DSB's is the vast amount of incorrect and misleading information being presented on their behalf. I have no problems with people that choose a DSB as their method. Heck, I still help people in my reef club design tanks around them if that's the way they want to go. I do have a problem when people present DSB's as a simple solution that has no downside. They aren't.

Your post is very elegant and clever but factually way off base.

I did not post here to disparage. I honestly commend you for your persistence. I still don't understand WHY you want to keep poop as a pet, but I don't understand why a blind guy feels the need to climb mount Everest, either.

You have my admiration for your attempts to find different solution. I'm sorry if my post conveyed any other message.

That is interesting and I appreciate the response. I'm not ruling out BB or anything that works better. We are on the same page about disinformation about DSB's, which was the reason for my post questioning Who Said This and the basis for CPW.

As a relative reef keeping newbie, I'm curious and looking for answers. As example, what are the indications or measurements you take to know your skimmer is under sized? You already have zero nitrates and do not use chemicals, what are the indicators for too small a skimmer? What is you present fish load in your 400 G set up?

I totally agree with get rid of the poop. But, over 50% of the detritus and bacterial detritus from animals in our tanks is p#ss, not poop. When I see my fish waste, very little if any ever reaches the bottom. It nearly all breaks up and goes into suspension and is carried into the tank flow. I have no visible detritus on the bottom to remove. It isn't simply a matter of taking out what settles on the bottom.

A skimmer goes a long way to doing this, but biological processing is still needed in a tank. I guess the only place we differ is how much biological processing surface is enough. I just feel you can't have too much, and it may be possible to make a DSB and asset and not a detriment to reef keeping. We agree, it isn't going to be through disinformation.

 

[Shoestring Reefer]

ldrhawke,

It sounds like you've found a way to breath life into the thread again.

When I see my fish waste, very little if any ever reaches the bottom. It nearly all breaks up and goes into suspension and is carried into the tank flow. I have no visible detritus on the bottom to remove. It isn't simply a matter of taking out what settles on the bottom.

I never realized how much of my sand bed was actually poop until I went BB. I have from 750 to 1000 gph (edit) in my 55-gal, depending on how many powerheads I have turned on. That inclused a Via-Aqua 2600 sitting on the botton. Every place where the rock meets the glass collects detritus on the glass where the rock shelters the flow.

Also, let me state it has become obvious over the last year that a good reef keeper can make any reef keeping system. Some systems are just more work and less forgiving than others.

:thumbsup:

I have yet to hear any BB advocates, that have converted to plastic bottoms, talk about or give reports on water quality since they have converted.

After removing my DSB and sump (I'll get a new one soon), mostly discontinuing use of my POS skimmer, and adding a fish, my nitrates went from undetectable to 2 over the course of a couple of months. 10% water changes once a week, my zoos and tulip anemones opened within an hour of being added to the tank and are doing fine.

Without a sump that can be used as a settling area, or a good filter, I have found detritus removal to be very time consuming, and I have not been able to keep up with it. One other problem I have is that when I increased my water flow, it caused most of my caulipera to break off of the rocks so I had to remove it, and I lost most of my algae-scrubbing capacity. After getting a sump/fuge and fixing those two problems (settling area for detritus and algae-scrubbing) I'll test for nitrates and let you all know how my BB system with algae scrubbing and an airstone-driven skimmer is doing.

 

[gregt]

...what are the indications or measurements you take to know your skimmer is under sized?

If it is constantly pulling out very nasty sludge even when the tank has not fed then it is undersized. A properly sized skimmer should have occasional periods when it isn't pulling much visible organic material out of the water. If you're always pulling out visible organic's then you still have room for more filtration.

You already have zero nitrates and do not use chemicals, what are the indicators for too small a skimmer?

See the above. If you're reading nitrates, then you are several stages too late to fix the problem. If you remove it before it breaks down, you don't need a large biological filter (which also adds bio load to your system) to deal with it.

What is you present fish load in your 400 G set up?

That tank is brand new and currently has only 3 small fish. This is why I'm not sure if my current skimmer is optimal or not yet, although I think I went big enough that it should be able to handle it. This is also the reason why I'm reserving judgement on what pump I will end up running on it and whether I will use the second injector port or not. Currently, I don't need either, but with a larger fish load, that may change.

I totally agree with get rid of the poop. But, over 50% of the detritus and bacterial detritus from animals in our tanks is p#ss, not poop. When I see my fish waste, very little if any ever reaches the bottom. It nearly all breaks up and goes into suspension and is carried into the tank flow. I have no visible detritus on the bottom to remove. It isn't simply a matter of taking out what settles on the bottom.

No, but everything that comes out of a fish, or a coral, or a bacteria and is dissolved in the water can be taken out by mechanical filtration such as skimming. I use the term "poop" as a colloqial term to cover all the "waste" Nitrogen products.

A skimmer goes a long way to doing this, but biological processing is still needed in a tank. I guess the only place we differ is how much biological processing surface is enough.

Biological filtration is needed. LR provide more than enough if your remove the bulk of the waste from the tank instead of trying to have a sewage treatment plant in the tank. This is the only pet I can think of that we consider keeping it in it's own waste "normal". Flush that toilet. :lol2:

I just feel you can't have too much, and it may be possible to make a DSB and asset and not a detriment to reef keeping.

I disagree. I think you can have too much. When your biofiltration become a load on the system it is supposed to be filtering, then it is too much. Also, the additional complications and dangers associated with larger biofiltration are a concern to me.

We agree, it isn't going to be through disinformation.

Absolutely. We also agree that sharing information and trying new things IS beneficial. Disagreement does not have to be followed with disrespect.

 

[ldrhawke]

I have from 750 to 1000 gpm in my 55-gal, depending on how many powerheads I have turned on.

I think you may be overstating the flow rates. I know you use eductors to boost flow, but a 1000 gpm is like refilling an empty 55 g tank nearly every couple of seconds. I can't picture much of anything living in the sort of turbulence other than what lives on the rocks on an ocean breaking barrier.

Looking forward to seeing your test results.

 

[Shoestring Reefer]

I think you may be overstating the flow rates. I know you use eductors to boost flow, but a 1000 gpm...

Whoops, that should have been 1000 gph, and I don't use eductors. I'll edit my post.

If I could afford 1000 gpm, I'd spend it on a bigger tank!:lol:

 

[Bomber]

I totally agree with get rid of the poop. But, over 50% of the detritus and bacterial detritus from animals in our tanks is p#ss, not poop. When I see my fish waste, very little if any ever reaches the bottom.

Well sorta/kinda, mostly from gills too though that you can't see at all.

It's still ammonia/ammonium --- nitrite ---- nitrate. No matter where it enters the conga line, it's still ending up as nitrates because of bacteria.

And that bacteria ends up as detritus.

I never realized how much of my sand bed was actually poop until I went BB.

Most of you guys entered the hobby with a DSB didn't you? You've never run a barebottom system?
That's why when we were trying to describe to you the massive amount of detritus that a DSB holds - you didn't have a clue what we meant!

On another note, all this talk about using a particular size sand grain for a sand bed seems kinda funny when you see all that particulate detritus, doesn't it Mike?

 

[aqua_obs]

Oh my gosh, I haven't read this thread for a while. The good Dr and shoestring are speaking to eachother! Truly CPW has advanced! Good show ole boys! reefs are the key to peace in the world!

 

[Scleractinian]

aqua_obs, I was shocked to see that too... I haven't been here in 15 pages or so...

BTW, ldrhawke, who was the quote from?

 

[ldrhawke]

Originally posted by Scleractinian BTW, ldrhawke, who was the quote from? [/B]

Drum Roooooolllllllll...................
:rollface: :rollface: :rollface: :rollface: :rollface: :rollface: :rollface: :rollface: :rollface:

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