DSB Heresy

[d-town tony]

A day in saranex is like a week in jeans and a t-shirt, I feel your pain, spent may days like that. I like continously supplied air respirators, scba's are ok, but only give you 15 minutes and are bulky.

 

[Scleractinian]

A day in saranex is like a week in jeans and a t-shirt, I feel your pain, spent may days like that. I like continously supplied air respirators, scba's are ok, but only give you 15 minutes and are bulky.

SCBA's not bulkier than draggin' an air line, especially if you're not sure what you might be dragging it through.

 

[d-town tony]

I hate SCBA's myself. I'd rather drag air-line any day. Especially when you're going through man-holes.

 

[brian crosson]

I love the concept and believe it works... However, I would like to give some criticisms (hope I do not offend).

The system you have works. There is no doubt your system works(at least not for me). You have combined a sand filter, plenum, and under gravel filter only you dump the fluidized sand bed?

I think you are siphoning off the fluidized sand bed too often. You have nominal biological filtration and a lots of mechanical that way...or so it may seem? What stops the bacteria from being sucked into the waste?

In addition, some concepts have gone awry. Reactants are sucked into your sand bed or the lower water levels making it more difficult for the air/light to dissipate (i.e. chlorine). Your trace elements will end up in your sand bed not your water column where you want them. The key to a true plenum is low water flow.

I have some torques I would like to run past and see if ideally you can give me some criticisms

What if you use the system in a sump... you can still maintain high current and circulation in the main tank. With lower circulation in the sump allowing reactants to fall naturally. Keeping trace elements and calcium where you want them. Also in the sump you would have marine plants that will use phosphates and nitrogen as fertilizer. The key problem to this is an 18" * 12" plenum is not sufficient for a 100+ gallon tank The key is to skim but under do it so as to keep the majority of good proteins.

The exact system I plan to use starts with 2 outside overflows. Water is pushed through an intake chamber contain shells and broken up live rock. Then skimming with an AquaC Urchin (suggested for 75 gallons or less) (I have over 200 gallons though. Then over a baffle to a refugium. Where the plenum lies beneath a 4 inch sand bed. The plenum is pretty much like yours (wholes are large though) it is connected to a bulkhead which has a small siphon pump. Lastly, I will incorporate one of rpgraff suggestions with a hang on filter with zeolite.

I think my system will provide the best of all worlds. A skimmer is best at getting water surface reactants. The plenum nonsurface reactants. And the zeolite pushing everything else! Next I would still vacuum the main tank substrate and once every other month empty part of the fluidized sand bed as part of a water change.

 

[ldrhawke]

I love the concept and believe it works... However, I would like to give some criticisms (hope I do not offend).

........... What stops the bacteria from being sucked into the waste?

In addition, some concepts have gone awry. Reactants are sucked into your sand bed or the lower water levels making it more difficult for the air/light to dissipate (i.e. chlorine). Your trace elements will end up in your sand bed not your water column where you want them. The key to a true plenum is low water flow.

I have some torques I would like to run past and see if ideally you can give me some criticisms

What if you use the system in a sump... you can still maintain high current and circulation in the main tank. With lower circulation in the sump allowing reactants to fall naturally. Keeping trace elements and calcium where you want them. Also in the sump you would have marine plants that will use phosphates and nitrogen as fertilizer. The key problem to this is an 18" * 12" plenum is not sufficient for a 100+ gallon tank The key is to skim but under do it so as to keep the majority of good proteins.

The exact system I plan to use starts with 2 outside overflows. Water is pushed through an intake chamber contain shells and broken up live rock. Then skimming with an AquaC Urchin (suggested for 75 gallons or less) (I have over 200 gallons though. Then over a baffle to a refugium. Where the plenum lies beneath a 4 inch sand bed. The plenum is pretty much like yours (wholes are large though) it is connected to a bulkhead which has a small siphon pump. Lastly, I will incorporate one of rpgraff suggestions with a hang on filter with zeolite.

I think my system will provide the best of all worlds. A skimmer is best at getting water surface reactants. The plenum nonsurface reactants. And the zeolite pushing everything else! Next I would still vacuum the main tank substrate and once every other month empty part of the fluidized sand bed as part of a water change.

No offense taken. As I have said before I expect people to modify the concept to meet their own needs.

Most of the bacteria is on and in the substrate. Periodic flushing and moving fresh food source by it will not remove any significant amount.

If any reactants are sucked into the bed, it is very small amounts, and I sure hope it isn't chloriine. I do not have any chlorine in my water column. If you have it in yours you have other problems. Yes, you are removing some trace elements using CPW, but no more than you do with any water change.

The CPW system I use is a periodic low flow pluse system. The total amount removed and transferred is much lower than a continuous flow plenum and is done in short surges to evenly move fresh material into and old out of the bed. Any low flow continuous system will short circuit because of the low flow.

A continuous low flow system will begin to act like a trickling filter and you will reduce denitrification in the bed and put it back into the tank. Continuous and high flow in a plenum has been tried before and people doing this had high nitrates. This is why the plastic balls are out of favor.

I fully agree skimming is the most important element in any reef tank.

If I understand correctly what you have explained you are doing. You are using the plenum waste to feed your refuge and are filtering and re-processing the discharge so you can recirculate it back into the tank.......this is not CPW.

CPW is a method of feeding the substrate bacteria uniformly with fresh food, to keep it from forming sulfides, and then simply wasting what is removed and not being concerned if you have full denitrification taking place. It removes no more than your normal water changes and allows you to replenish the trace elements being used with fresh salt mix and new trace elements to maintain a constant SG. Why do you want to even try to treat and process the CPW waste when it is less than what you do in 10% weekly water changes?

What you have is a trickling filter or bio filter in series with your filtration system, not CPW. I am not sure if what your are doing will be helpful or not, it is potentially putting untreated nitrates back into the water column and then trying to skim them out to remove them. On the positive side it will make you substrate more effective and reduce the potential of it going sour.

Drilling more and larger holes in the plenum will cause more maldistribution and not evenly pull the water column through the bed. You could have purchased any store bought bottom filter and had the same thing. Obviously you don't agree with or understand with what I have tried to explain on other occasions about reasons for maldistribution in commercial bottom filters and the reasons for restricting the flow.

The only real down side I see to what you are doing is that you may be putting nitrates back into the water column, which CPW is designed not to do. You have a lot going on after the water leaves the plenum and the zeolite may help, but everything I read says zeolite is useless in salt water to remove nitrates. Keep us informed of your nitrate levels. It is a different approach. Good luck.

 

[brian crosson]

I am not reusing the waste. My holes are only a 1/32 of an inch larger than yours.

The key is one month (during water changes) I will remove water from the main tank. The next beneth the plenum.

Chlorine is a gas when you wash your white clothing/ towels and they dry out the gas is transfered into the air. Water natually picks things out of the air. Even RO/di will not get out 100% of toxins. I think the RO filter from dupont advertises 99.99% there will still be trace elements of chlorine. Though probably not readable by any test.

Lets say for theory puroposes that this is small amounts of toxins in your water specifically chlorine. your concept of off on with the pump would pull the gas deep into the tank which naturall escapes the surface of water. It is not a hugh or even signifigant problem. but over time you may poison your sand bed though it may take several decades.

Mine concept being on a smaller level water change wise and plenum size may take centuries.

3 levels in the aquarium;

the surface where thing are removes by light air and skimming

The center and water column. water changes, plants, mechanical filtration

The bottom deep sand beds and plenum etc.

Your plenum idea fixes some of the problems with the deep sand bed and plenum

The key is the plenum accepts nitrates breaking the down to nitrogen which is harmlessly removed at the surface your concept stops the surface exchange from happening. My problem with it is it is not only that nitrogen but any gas.

The next is a skimmer is used to remove organic wastes before nitrifying bacteria act upon it therefore technically in a manner of speaking your need to skimm first.

I am not an advocate of overskimming as the phosphates in small nonleathal portion will help Zooxanthellae. Also either Macro or micro proteins (I get them confused) are good for the aquarium over skimming takes out both.

by doing all the workin the sump my fauna still get their food source in the main tank.

I am sorry I am obviously very biased in my planning. A good chop to the block would be benificial. If my explaining of the mod is still hard to grasp due to my poor writing abilities. I will try to take pictures in a couple of months when completed!

Also I intend to perform experiments test water quality after skimming, after plenum nitrifing, waste removal, and zeolites in record the results on DFWMAS.

 

[ldrhawke]

The key is one month (during water changes) I will remove water from the main tank. The next beneth the plenum.

Sorry, I don't understand the reasoning!

Chlorine is a gas when you wash your white clothing/ towels and they dry out the gas is transfered into the air. Water natually picks things out of the air. Even RO/di will not get out 100% of toxins. I think the RO filter from dupont advertises 99.99% there will still be trace elements of chlorine. Though probably not readable by any test.

Lets say for theory puroposes that this is small amounts of toxins in your water specifically chlorine. your concept of off on with the pump would pull the gas deep into the tank which naturall escapes the surface of water. It is not a hugh or even signifigant problem. but over time you may poison your sand bed though it may take several decades.

I was also concerned about chlorine in the form of chloramines, fromm our water system. I have used a Hach test and found no indication of any chlorine or chloramines after my RO/DI which has a triple carbon filter on it.

I do not believe any chlorine in ppb in the air will get into the water and then be drawn down into the substrate with CPW and build up. Unless, you have your tank in a commerical laundry.

Plus, if ppb of chlorine do get into the water they will react quickly and be spent. They will not build up. It is a highly reactive chemical. Chlorine will be react and spent quickly and chloramines released more slowly, over days, but they will not concentrate in the substrate over time.

I will try to take pictures in a couple of months when completed!

Also I intend to perform experiments test water quality after skimming, after plenum nitrifing, waste removal, and zeolites in record the results on DFWMAS.

Looking forward to seeing the pictures and reading about your results.

 

[brian crosson]

If you are changing out the water just beath the sand then the reactant has to get below the sand bed. The reactant may never get below the sand?

Still your focusing on chlorine to much it is a generalization there are other gases and liquids... they will get into your tank! Just because a test doesn't detect it doesn't mean it's not there. Have you done soil samples? It's obviously not very realisting to do one on a tank.

The point is the way your system works will force things into the sand bed. It may be a decade before it chrashes but it will still crash. You haven't eliminated the problem just extended the duration.

 

[ldrhawke]

The point is the way your system works will force things into the sand bed. It may be a decade before it chrashes but it will still crash. You haven't eliminated the problem just extended the duration.

You forgot to take into account, CPW is also removing waste build up from the sand bed. The whole idea of CPW is to stop the build up beyond the point that nitrification is retarded. What is being filter out in the bed is food for the bacteria. Also keeping be bacteria fed means there will be more available to process the waste.

There are bacteria that will eat virtually any type of carbon waste....even gasoline and PCB's ....

 

[DennisRB]

What use is the system if all the DSB processed water eventually ends up in the sink?

This is how I see CPW in order of the events.

Tank water enters DSB > it gets denitrified > it has a chance to become putrid > in ends up in the sink.

In other words, relatively clean tank water is putrefied then thrown in the sink. You may as well get some tank water. Put in a sealed container for 2 weeks, comment how much in stinks then throw in in the sink. The results will be similar.

You may as well have a shallow sand bed. The results will be the same as CPW. CPW basically makes the bottom part of the DSB redundant because any water in it will be thrown in the sink.

Similar comments have been made though this thread with no replies.

These ideas may be wrong, but I'm yet to see why. They seem to make logical sense.

 

[ldrhawke]

What use is the system if all the DSB processed water eventually ends up in the sink?

This is how I see CPW in order of the events.

Tank water enters DSB > it gets denitrified > it has a chance to become putrid > in ends up in the sink.

In other words, relatively clean tank water is putrefied then thrown in the sink. You may as well get some tank water. Put in a sealed container for 2 weeks, comment how much in stinks then throw in in the sink. The results will be similar.........

Now you've described our hobby..

Maybe you can describe your system, how long you've been at it, and what type of coral and fish you keep to see how you process waste differently. I'm always open to better ways......Just trying to get my head around the science of it.

 

[DennisRB]

"Maybe you can describe your system, how long you've been at it, and what type of coral and fish you keep to see how you process waste differently. I'm always open to better ways......Just trying to get my head around the science of it."

I will gladly admit I no marine experience at all. So I am trying to get my head around the science of it. However I have been doing extensive research for over one year, just because I love nerding up on stuff like this. I have learned a lot through other peoples experience. This of course can't be compared to hands on experience. I also have the habit of always wanting to know how stuff works before I use it. (when I'm interested in it anyway)

I am in the middle of setting up a 150G reef. look here for the current progress It will probably have a shallow sand bed in the display tank and a DSB in the refuge. This way the DSB can easily be replaced if it goes bad.

I don't think my experience level really has anything to do with the point I was making about CPW. I'm sure you understand exactly what I meant in my last post. You did not address the issue of the DSB redundancy (yet again). Instead you asked me about my experience and system. This thread is supposed to be about CPW is it not?

I actually though of your idea the first time I came upon an article about a plenum. I immediately wondered what having a stagnant volume of water under a DSB is supposed to achieve. I thought of draining the plenum and then dismissed it for the reasons I gave in my last post.

The view I have on CPW at the moment is that, all it achieves is the processing of tank water before it gets thrown away. Why bother processing the water with a DSB if it will get thrown out anyway? In effect its like claiming your tank will benefit by doing a water change then treating the water you just took out of the tank before throwing it away.

Surely you understand my point? I think this point deserves some explanation on your part if CPW really is all you say it can be. I'm not even saying CPW is no good as there might be something I have missed in my reasoning. That is why I eagerly await your reply.

Just trying to get my head around the science of it

 

[Shoestring Reefer]

What use is the system if all the DSB processed water eventually ends up in the sink?

That's been brought up over and over, and no one else has tried to give a good answer, so I'll give it a shot.

Yes, processed water ends up in the sink. I suspect it will have similar results to mechanical waste removal. The goal of this method appears not to use the DSB as a biological filter, but rather to delay or prevent the day that the DSB will contribute to algae growth.

There are people who just want a DSB, plain and simple. They may have animals that require one (such as jaw fish), they may want the DSB for it's "forgiving" nature, they may not be able to afford or set up a high-end skimmer and high water flow, they may keep some invert that prefers low-flow and they believe it will benefit from some DSB-supplied food, they may just like the look of DSBs, or they may want to experiment with something new. If someone falls in that category, and they think they will have their tank set up for a few years, then ldrhawke's method may be something they feel is worth trying.

I ultimately want an in-wall SPS tank. From what I've read, they do best in very nutrient poor water, accomplished with heavy, wet skimming, as well as high water flow. I don't have a system anything like that right now, but I removed my DSB to make my system "less forgiving" so I could use this time to practice (as much as I can) the husbandry techniques needed for the tank I someday want to have. If someone wants to stick to leathers or jaw fish, and is scared the DSB will someday contribute to algae growth, then maby ldrhawke's method will help them sleep better.

 

[ninja750]

My thoughts:-

I like the idea of a DSB. I want it to "protect" my tank if their is a spike. The forgiving nature of the DSB l believe out weights the con's. I had a long chat with my lFS owner about DSB's, and he kept on going how everyone's DSB's are crashing. I would like to use the CPW method to prolong the DSB fro a few more years than is normal - average 3 years, hopefully with CPW where the nutrient buildup is removed before it becomes a sink, will allow the dsb to last say 5 years.

ldrhawke / anyone - I have a 5'x3'x2' tank with 2 x corner weirs of 150mm x 200mm. Does anyone have any ideas about a simple piping system to be utilised for the CPW method???

I am useless with anything other than a computer (IT technician) so it needs to be really simple.....:rollface:


HI dennisRB, your tank is looking good. Will see you around on the MASA board....:strooper:

Linh

 

[DennisRB]

"Yes, processed water ends up in the sink. I suspect it will have similar results to mechanical waste removal. The goal of this method appears not to use the DSB as a biological filter, but rather to delay or prevent the day that the DSB will contribute to algae growth. "

An even better way to delay or prevent the day that the DSB will contribute to algae growth is by not using one.

As far as I know a DSB is a biological filter. Right? I sure we can all agree on that.

If your not going to use it as a biological filter. Why bother having it in the first place? Why not just use a shallow sand bed? It seems to me the results will be similar, eg limited biological filtration and it won't crash and release toxins.

As I am setting up a tank right now, I am looking for new ways of doing things. ATM I can't see the benefit of a CPW DSB compared to a shallow sand bed. Maybe if you hate DSBs and want livestock that needs one, it might be a good idea but other than that I can't see any benefit.

Why use CPW if it makes the bottom part of the DSB redundant?

Hi Ninja. Make sure you post some pics when you set it up

 

[ldrhawke]

"Maybe you can describe your system, how long you've been at it, and what
type of coral and fish you keep to see how you process waste differently.
I'm always open to better ways......Just trying to get my head around the
science of it."

............

The view I have on CPW at the moment is that, all it achieves is the
processing of tank water before it gets thrown away. Why bother processing
the water with a DSB if it will get thrown out anyway? In effect its like
claiming your tank will benefit by doing a water change then treating the
water you just took out of the tank before throwing it away.

Surely you understand my point? I think this point deserves some
explanation on your part if CPW really is all you say it can be. I'm not
even saying CPW is no good as there might be something I have missed in my
reasoning. That is why I eagerly await your reply.

Just trying to get my head around the science of it

Maybe this will help. I have said most of this before but it helps in my
own thinking to reiterate somethings. In fact, some of my original thinking
has been challenged by my own recent post to the "coil denitrator size" and
water change dilution math.

Let me start with a few basic assumptions i have made in the CPW concept:

1. DSB's do work and help in reducing nitrates.
2. DSB's can fail and often do from going "sour*"
*sour meaning anoxic conditions can get out of control and
release phosphates and other waste back into the water column.
3. DSB's have additional benefits in that they are a large biological filter
that rapidly helps to reduce ammonia and nitrites, act as a pH buffer,
release bacteria for coral to feed on and generally stabilize the the tank
conditions.
4. Some have been successful in keeping DSB's for relatively long and trouble
free periods.
5. DSB's have some strong positives aspects in keeping a reef tank.
6. DSB's have some strong negative aspects in keeping a reef tank.
7. The majority of reef tank keepers agree 10 to 25% regular water changes,
every week or month, are necessary in successful reef keeping.
8. Trace elements are used up in a reef tank and the need to be
replenished. Water changes with fresh salt mix is a good way to replenish trace elements.
9. Toxic waste from some corals can build up and need to be removed.
10. The nitrification and denitrification bacteria need to be fed and
populate and be available for waste loading.
11. The denitrification bacteria, once establish, can survive and actually
increase and thrive as the spent nitrates move into the lower layer. The
temporary increase in oxygen will quickly stabilize and anoxic conditions
quickly return because the de-nitrification bacteria is being positively
fed.
12. CPW still needs the support of good husbandry practices and a good
skimmer. It an additional tool and process to assist in reef keeping.

The question then becomes is there anything that can be done to reduce or eliminate the negatives of a DSB, keeping the points above in mind.

This why the CPW concept was developed. To maintain or improve the positive aspects of a DSB and keep it from flipping anoxic and going sour. Not only to keep it from going sour but to increase both the oxic and anoxic bacteria population.

Controlled Plenum Wasting allows the water column above to gradually move into substrate bed and move waste (food for the bacteria) through the nitrification cycle.

The substrate is still acting as a biological filter, as it does in a conventional DSB, with water in it entering back into the water column above it, even with periodic negative flow into the bed.

The questions still unanswered is how frequently and how much movement into the substrate bed is optimum. Is there an upper limit that will totally stop denitrification in the bottom of the bed. Is there a lower limit that allows the bed to go sour.

If CPW is used as an adjunct to normal water change practices, there will probably no or little increase in the amount of water normally changed on a regular basis. On the other hand, there will be little or no decrease.

I say this because of a recent realization. Trying to use daily wasting at reduced flows and numerous small volume changes, and attempting to replace regular water changes, will not work very well. (see my post in: Advanced Topics > coil denitrator size). I just realized the same recycle dilution principles apply to CPW. Even if you use CPW to keep your DSB refreshed, you will still need to make larger periodic water changes or you will still get a build up of waste in your tank.

This is what happened to me several weeks ago when I was only using the CPW to replace water changes. The water quality started to drop below 300mv in the ORP meter.

Hope this answers why use CPW. And why it is simply not a fancy way to make water changes. By the way Dennis nice job on that tank. Look forward to see progress photos posted.

 

[DennisRB]

Do you still view the CPW DSB as a biological filter? I don't think you gave a direct answer to the DSB becoming redundant. I'm sure de-nitrification will work great with CPW DSB, too bad whatever gets processed will get dumped.

Surely any water in the lower levels will not mix up with the tank water and consequently just be thrown away? You talk about water slowly going down into the DSB and becoming denitrified. I'm saying it is irrelevant what happens in the CPW DSB as any products will be drained off.

I think CPW eliminates the bad points of DSBs but also eliminates the point in having one in the first place.


That tank build is going fairly slow. Just keep looking in the link I gave for updates.

 

[ldrhawke]

Do you still view the CPW DSB as a biological filter? I don't think you gave a direct answer to the DSB becoming redundant. I'm sure de-nitrification will work great with CPW DSB, too bad whatever gets processed will get dumped.

Surely any water in the lower levels will not mix up with the tank water and consequently just be thrown away? You talk about water slowly going down into the DSB and becoming denitrified. I'm saying it is irrelevant what happens in the CPW DSB as any products will be drained off.

I think CPW eliminates the bad points of DSBs but also eliminates the point in having one in the first place.

I don't think you read or at least fully comprehended what I said. I did addressed all of you comments. Let me ask you a few questions.

....and the point in having a DSB is....?


....but it eliminates the bad points of a DSB, which are?

You contend nothing is released back out of a DSP if it has a periodic postive flow into it and remove waste off the bottom.

At what point does CPW not act similar to a DSB? If I remove a quart once a month or when remove a gallon every hour? Or what point inbetween does the biological activity never flow out of the CPW/DSB and into the water column above?

I think after you get water in your tank and attempt to maintain water quality, a lot of you're opinions will moderate. Keep the pictures coming.

ps...I wouldn't reference back to another another online community on RC to view photos. Don't ask me how I know.

 

[DennisRB]

deleted double post

 

[DennisRB]

lol, thanks for the tip

You know it is possible to still disagree, even after reading and comprehending what you were saying. Your big post lists some points on DSBs, and sets targets for what you claim CPW can do. It still did not address DSB redundancy. I agree with all the numbered points you made.

"I think after you get water in your tank and attempt to maintain water quality, a lot of you're opinions will moderate. Keep the pictures coming. "

That has absolutely nothing to do to with the theoretical points I am trying to make.

"....and the point in having a DSB is....?"

I was wondering what your opinion on this matter was, considering that you are throwing away any water that has been treated by the DSB. DSBs denitrify the water by allowing a very slow flow of water to low oxygen zones where anoxic bacteria use nitrate as food.

"This why the CPW concept was developed. To maintain or improve the positive aspects of a DSB and keep it from flipping anoxic and going sour. Not only to keep it from going sour but to increase both the oxic and anoxic bacteria population."

I'm sure CPW can draw enough water into the DSB to prevent it going anoxic, sour etc. (so what if the water gets dumped)

"but it eliminates the bad points of a DSB, which are?"

They can go bad after time by releasing toxins and from anoxic zones back up into the water. They can release phosphates and other compounds back into the water after a long time. They take up valuable tank space. They look ugly.

CPW might tackle the first 2 drawbacks but it also counteracts the point in having a DSB by disrupting the normal slow flow of water in and out of the DSB. Instead of water flowing in and out at a slow rate. It only flows in the DSB then into the sink. Rendering the beneficial effects of the DSB useless. *



"At what point does CPW not act similar to a DSB? If I remove a quart once a month or when remove a gallon every hour? Or what point in between does the biological activity never flow out of the CPW/DSB and into the water column above?"

* YAY You are finally starting to address the real issue of DSB redundancy. I would love to know the answers to the questions you asked in the paragraph above. I think you should know these answers before you hail CPW as the holy grail for DSBs. Without that knowledge you can't say that the DSB is not becoming redundant. (though I can't say that it is either!)

It has to be determined if the level of wasting required to maintain safe DSB conditions is not too high to stop water transfer between the DSB and tank water.