DSB Heresy

[ldrhawke]

I'm still intrigued by the possibility of automating the release of effluent (hence my questions about monitoring the nutrient parameters of the effluent and about the dose/waste volume interval and periodicity)... I realize that the plenum ORP/tank ORP relationship wouldn't be quick or tight...

One potential thing to monitor might be pH of the waste discharged. Keeping the waste in the DSB for more than 30 days appears to cause the pH to drop into the 4's.

If the pH is used as a control, as example, a controller could discharge at 4 and stop at 6. That may allow the DSB to drop low enough to allow phosphates and SI O2 to be removed. Just a thought. Needs a lot of testing to verify.

 

[keman]

Interesting question:

How much of a biohazard is the drained 'liquor' going to represent?

Should gloves be worn when handling the storage container for emptying, etc?

I grew up gravel vacuuming fish tanks, pulling dead fish out (worked at a LFS for many years) and eating food randomly always with bare hands. Never had any problems ... but.. this reminds me of a phrase I once heard:

"BMW Motorcycles never used to overheat.. until they started putting temp gauges on them."

 

[ldrhawke]

How much of a biohazard is the drained 'liquor' going to represent?

Should gloves be worn when handling the storage container for emptying, etc?

Easy with that biohazrd stuff.....we may have a greenie or an EPA advocate reading this stuff.

Next thing we know we will have to a a license to keep a reef tank and "big brother" will be monitoring our every move. We won't be able to empty any waste into the sink and we we all have to build a pretreatment plant or have a separate hazardous waste container at our drive way.. :bum:

 

[BORECKI]

irdhawke; perhaps a picture is worth a thousand words. Looking at your gallery, I did not see enough pictures of the actual under sand piping, nor how the holes are protected from cloging (the fabric). Could you be kind enough to make a mockup of a section of the pipe wraped with your fabric and post a few pictures?
Again; I don't think the concept of draining away the soup from the DSB is what's in question but rather the mechenics of the sistem.
turtlesteve; I think your idea of tuning the plumbing so that all the holes have an equalized distance/friction is a stroke of genius. (Just like tuned pipes of high perfomance cars & bikes)Taking that concept further, one can go a size smaller in plumbing (provided it's available at the local plumbing shop) and realy set up a very uniform grid on the bottom of the tank with LOTS of branches. One could even get out of the two dimentional drawing you did and go up with some of the cross pipes to crowd even more tubes under the sand. The end pipes would be at the bottom and the cross members one step above; the DSB will hide the whole thing anyway.

I only hope that raising questions is not a sign of being an idiot:mixed:
Boris.

 

[ldrhawke]

irdhawke; ... Could you be kind enough to make a mockup of a section of the pipe wraped with your fabric and post a few pictures?
Again; I don't think the concept of draining away the soup from the DSB is what's in question but rather the mechenics of the sistem.
turtlesteve; I think your idea of tuning the plumbing so that all the holes have an equalized distance/friction is a stroke of genius.

I only hope that raising questions is not a sign of being an idiot
Boris.

If I get some time, I'll try to mock up something so you can see a picture to explain the mechenics of the sistem. Right now I am not even sure if I will be in town next week.

There is no need to equalize the distance for the holes with 1/2" pipe only flowing a gallon a minute. There is no measurable friction loss in the piping to tune at this low flow a flow rate. It is only .04 ft of head loss per foot of pipe. Divide .04 by the number of total pipes, because the flow divided. You would have difficulty measuring any friction loss.

Questions are never a problem. It is arrogant condescending personal attacks that become a problem.

By the way didn't you run your plenum in reverse and clean the substrate regularly. I tried that for awhile but my water quality was a problem when I did it.

 

[Shoestring Reefer]

Phosphate

Phosphate

I have been monitoring. There are continuous low levels of phopshate, pH, and nitrates in the wasted fluid....I have not mesured for SiO2.

There is little or no measureable level in the water column above. The most obvious thisng is the rotten egg odor present for several weeks in the low level wasting fluid. After a several weeks of wasting the rotten egg smell in the wasted fluid went away. The low levels of nitrates and phosphates remained. pH is always about .4 to .5 lower in the wasted fluid.

Ok, now maby we have a little data to work with, regarding long-term functionality. First, a some clarification:

There are continuous low levels of phopshate, pH, and nitrates in the wasted fluid....I have not mesured for SiO2.

By low levels, do you mean that there are detectable levels, rather than undetectable levels?

I have been monitoring. There are continuous low levels of phopshate, pH, and nitrates in the wasted fluid....I have not mesured for SiO2.

There is little or no measureable level in the water column above. The most obvious thisng is the rotten egg odor present for several weeks in the low level wasting fluid. After a several weeks of wasting the rotten egg smell in the wasted fluid went away. The low levels of nitrates and phosphates remained. pH is always about .4 to .5 lower in the wasted fluid.

In the first sentence of the second paragraph quited above, are you saying there are unmeserable levels of phosphate and nitrates in the water column, or just SiO2. I don't think ANY levels od SiO2 in the water column would make sense, but I want to make sure I understand what you are saying.

If there is undetectable levels of phosphate in the water column, yet you have detectable levels in the waste water, then the bed is already a phosphate source. The constant removal of waste from the bottom bed may help limit phosphate release into the water column, but what happens between the waste removal? Will phosphate retention and release continue to occure higher and higher in the bed, until it is close enough to the water column to affect water quality? Or, will increase waste removal eliminate phosphate in the waste water?

If, on the other hand, if phosphate levels are undetectable in the waste water and the water column (or can be made to be undetectable with increased waste removal), and can stay low long-term, then that would be a sign that phospate problems are a non-issue with this method.

 

[Shoestring Reefer]

To put it another way...look at what most everone is doing right now in an effort to make DSB's amd BB's work.

What, exactly, are people doing to make BB's work that is not required with yuor method? From what I understand, the BB method requires skimming.

To put it another way...look at what most everone is doing right now in an effort to make DSB's amd BB's work. It is now almost accepted fact by most that DSB's will fail.

Ok, so why not just go BB? What advantages does your idea have over BB? One original theory with DSB was that it would provide food for corals, and a breeding place for fauna like pods, etc, while providing biological filtration.

I have read numerous posts saying they believe the DSB contribute little to providing food for corals. I think your system would provide even less, considering the frequent waste water removal, which will just pull potential food away from the water column.

As far as a home for fauna, consider the recommendations for mandarines, which rely on pods for food. Recommendations are given for amounts of live rock and system maturity; substrait seems to be a minor consideration. Any fauna may end up too low in the bed to be of any benifit, anyway, because that's where the detritus will end up.

I think any biological filtration is irrelivent, becaust the water is just leaving the system, anyway. I'll let the town deal with handling my waste water.

 

[Shoestring Reefer]

Hole diameter and clogging

Hole diameter and clogging

Plugging of the holes is apotential problem; one recommendation for addressing that concern is to place "filter material" over the pipes (or plenum, if used) to prevent the plugging of holes.

The problem, as I see it, is that the filter material will still get plugged. That's why people using canister filters for circulation are recommended to remove the filter media.

A better solution may be to use larger diameter holes to allow detritus to pass through, eliminating the need for a filter material over the holes. The substrait used would be coarse enough to not blocg the tubes, and its coarseness will reduce substrait clogging, as well.

 

[BORECKI]

..........By the way didn't you run your plenum in reverse and clean the substrate regularly. I tried that for awhile but my water quality was a problem when I did it.

No, when I was running a refugium/DSB over a plenium it was sealed as per Jalbert.
One thing I'd like to raise about the behavior of sand under water pressure; It will compact or turn into quicksand depending on the direction of the water flow. It should be quite interesting to see what happens to the sand with backflow pressure when one is uncloging any holes
Boris.

 

[ddoering]

Hi,

Interesting thread.

Isn't this basically an under gravel filter? You are proposing to use the sand bed for it's surface area, and instead of recycling the water passed through the gravel/sand, you are exporting it as waste.

Exporting concentrated waste is the most efficient I guess, like exporting macroalgae or using a skimmer to condense wastes into sludgey skimmate to remove from the tank.

Do you expect the bed depth to make much difference besides giving more area with deeper beds for more bacteria?

Are there some byproducts in the tank that won't be soluble and so will not be siphoned out over time? I thought that the problem with DSB over time was that they basically filled up and could no longer absorb more wastes. I thought this included solid wastes as well.

Would you expect problems with this using a shallower bed with finer sand (and smaller holes in the pvc?)

Do you have to worry about calcium carbonate buildup in the pipes which would require cleaning out the tubes? Having to try to tear apart a tank to get the pipes out to clean them would be like redoing a DSB tank in a few years to prevent old tank syndrome.

What is the real worry with DSB? Is it the accumulation of Hydrogen Sulfide? Or do people more have a problem with phosphate buildup and then algae nightmares?

The holes on the PVC, are you drilling them on the sides of the PVC, all around the PVC or what?

Thanks,
Doug

 

[keman]

Easy with that biohazrd stuff.....we may have a greenie or an EPA advocate reading this stuff.

Next thing we know we will have to a a license to keep a reef tank and "big brother" will be monitoring our every move. We won't be able to empty any waste into the sink and we we all have to build a pretreatment plant or have a separate hazardous waste container at our drive way.. :bum:

Sorry, Biohazard was probably not quite the term I'm looking for. I doubt this stuff represents any hazard to the environment. Like any living environment though however, there will be some things that represent a hazard to us fleshy land dwellers. Someone brought up an interesting point on the topic of cutting live rock, for instance-- one I had not considered prior. Don't inhale the spray from a saw if you use one, as it can contain some very bad things.

What I'm interested in is how unhealthy this stuff would be to injest or otherwise come in contact with my skin?

Are we talking... rotting old hamburger unhealthy, or... ?

 

[ldrhawke]

Hi,

Interesting thread.

Isn't this basically an under gravel filter? You are proposing to use the sand bed for it's surface area, and instead of recycling the water passed through the gravel/sand, you are exporting it as waste.

Exporting concentrated waste is the most efficient I guess, like exporting macroalgae or using a skimmer to condense wastes into sludgey skimmate to remove from the tank.

Do you expect the bed depth to make much difference besides giving more area with deeper beds for more bacteria?

Are there some byproducts in the tank that won't be soluble and so will not be siphoned out over time? I thought that the problem with DSB over time was that they basically filled up and could no longer absorb more wastes. I thought this included solid wastes as well.

Would you expect problems with this using a shallower bed with finer sand (and smaller holes in the pvc?)

Do you have to worry about calcium carbonate buildup in the pipes which would require cleaning out the tubes? Having to try to tear apart a tank to get the pipes out to clean them would be like redoing a DSB tank in a few years to prevent old tank syndrome.

What is the real worry with DSB? Is it the accumulation of Hydrogen Sulfide? Or do people more have a problem with phosphate buildup and then algae nightmares?

The holes on the PVC, are you drilling them on the sides of the PVC, all around the PVC or what?

Thanks,
Doug

Truely...not being a wise guy, but virtually everything you've asked has been answered if you start reading from page 1.

With regard to actual required service of A CPW system over time...only time will answer that. I'd just be guessing.

I don't believe calcium carbonate will build up in an area that tests show that pH's can drop well below 7.

 

[ldrhawke]

Sorry, Biohazard was probably not quite the term I'm looking for. I doubt this stuff represents any hazard to the environment. Like any living environment though however, there will be some things that represent a hazard to us fleshy land dwellers. Someone brought up an interesting point on the topic of cutting live rock, for instance-- one I had not considered prior. Don't inhale the spray from a saw if you use one, as it can contain some very bad things.

What I'm interested in is how unhealthy this stuff would be to injest or otherwise come in contact with my skin?

Are we talking... rotting old hamburger unhealthy, or... ?

I wouldn't drink it


I'd be a lot more worried about the junk in my skimmer.....ikky, bad, no good, not nice:lol:

Just cleaned my skimmer out tonight:eek2:

 

[Shoestring Reefer]

Re: DSB Heresy

http://www.ozestuaries.org/indicato..._reduction.html

The above link is not working for me. I found the page here:
http://www.ozestuaries.org/indicators/Def_sulphate_reduction.html

 

[Randy Holmes-Farley]

The only conflicting views are from people that simply do not want to accept the data below and feel they have some way to improve upon what I have described it takes to build a CPW system to work effectively.

Just a comment here that we will probably address more in the chemistry forum. Note that some of these test kits involve redox chemistry. A little nitrite shows up as a lot of nitrate in some kits, for example. Since the plenum is a reducing situation where there may be redox species like nitrite and sulfite and other things, I tend to worry about the primary data that was generated by Thiel (not a chemist), and is being used to test these systems as well.

 

[ddoering]

Hello,

I did read through beginning at post one before posting my questions, and as I was unclear on things, I asked questions.

Simply referring me back to what I have already read does nothing to clear up any questions I have. If something was already stated, and somebody asks a question on it, try rewording your explanation, as this might clarify the issue.

Your first post states in the description of your tank you are using a 5 inch sandbed of coarser media than usually recommended for a DSB. Later you state it is between 3 and 4 inches.

You state you are using Carib Sea Special Grade Sand, which was later said to be approximately 1 mm (10x coarser than sugar sand).

"Also, remember I do not believe in using fine sugar sand. I believe it is far to dense and leaves little open area to allow adequate fluid flow. I use a very uniform coarse crushed coral that is designed for exactly what I want. Pore space for fluid movement to reach deep into the bed"


My question to this is what is the difference between using a coarser media 5 inches deep, or using a finer media that is perhaps 2 or 3 inches deep?

The smaller particles will provide much greater surface area for bacterial populations than the coarser media, so should improve the biological filtration.

You will not take up as much viewing area in your tank as a 5 or 6 inch bed if you could use a shallower bed with finer particles. You should still get the oxygen depleted areas without needing the same depth, but could prevent the completely oxygen devoid areas by reducing depth of finer grain substrate so it is not a DSB anymore.

Now I don't know about fluid flow, but wouldn't you be able to get adequate fluid flow through a shallower bed? Also, wouldn't a bed of finer particles help combat the channeling of fluid through an area of least resistance? I would think a coarser media would be more likely to channel, since the finer material would settle more and be moved around more by the water flow to fill in any channeling that occurs. You state that detritus will block pores in a finer substrate leading to dead zones. Wouldn't a finer substrate result in detritus being caught higher up in the sandbed in the oxic zone, where bacteria and microfauna can get at it? As opposed to it being sucked down so far into the coarser bed in an anoxic zone etc?

Using the finer substrate would also allow for people to keep the sandbed fauna that people want to assist with cleanup and recycling of wastes in the form of food organisms, or just for the novelty of having those different critters. Wouldn't sandbed stirrers also prevent the dead zones since they would stir up finer sands that would break up any clogging.

This is why I was asking about the depth of the bed, and possible use of finer sand substrate.

You stated your opinion that you would use a coarser media, but I don't understand why a shallower bed of finer media would not also be affective. Can't you get water to flow through the bed of finer material? Can't you get the same pressure drop by using smaller holes in the PVC pipe? Or would you need a longer drop for the siphon tube to increase pressure drop through a fine sand bed?


I asked about whether there were solid components to the waste that builds up in the sandbed that we should be concerned with. I don't see this really being addressed in this thread besides you stating that the bacteria should eat everything and it will all be in solution. I think more measurments on the contents of your wastewater, vs what you are adding in the way of food and salt etc should be done. Try to correlate inputs to outputs, that way you will see what is building up possibly in your system. Some things will be incorporated into biomass of fish and corals, but other things are probably still accumulating and filling in your coarse sandbed like any other DSB. The question is... what?

Have you done any sampling of your bed, like a core sample so you can check for accumulating solids and preciptates?

The waste water you are throwing away, is it a higher concentration of heavy metals like copper? Or are these still possibly accumulating in your system so that after a 2 year period, you will have a crash just like DSB? Long term data would help show possible things to be concerned with.

This also relates to why I asked what the actual downfall of DSB really is. I know this has been debated, and some people say it is accumulation of phosphates leading to an algae bloom that consumes oxygen and basically suffocates other inhabitants in the tank. Others say it is accumulation of heavy metals that eventually gets to toxic levels leading to mass die-off. Others think the DSB is not diverse enough or large enough to support enough critters to efficiently recycle materials, leading to buildup and eventual crash of the sandbed.

From reading what you have stated, my interpretation is that you
believe that drawing water off from low in the sandbed will resolve the crashing of DSB, but why? Your proof that your system is working is the lack of rotten-egg smell in the waste water, meaning less hydrogen sulfide in the waste water.

I would like to see more testing over time of what is being drawn
off in your waste water, as well as testing to see if there is
anything still accumulating within your coarser bed.


I asked about possiblities of buildups in the pipes because that is
something that would eventually lead to having to tear down the
system, which would be a complete overhaul of a tank since you
are covering the entire bottom with the PVC tubing.
Since you have different PH in the water that is sitting in the tubes, and then flushing them and filling them with water of a different PH which will sit for hours/days etc, the water parameters will change while the stuff sits in the pipe. Since PH can drop over time, could this lead to salts or other precipitates that will accumulate in the pipe and eventually lead to failure? Again, without long term data to see if the pipes fail over time because of buildup, people are going to be skeptical of claims that your suggestion will fix long term problems with only short term data.


You also state you are using 1/2 pvc with 1/32 inch holes drilled
approximately every 2 inches. The only people I see who made suggestions for orientation of the drain holes in the PVC were Shoestring Reefer and Borecki. Do you drill the holes, on top, bottom, or side of the pvc, or all the way around the circumference of the pipe.


Sorry for the lengthy post, but my questions were not from a lack of reading... lack of understanding yes.

 

[ddoering]

Another thing that people setting this up should keep in mind.

I noticed that you have suspended your live rock on a platform to elevate it.

This is probably needed to ensure less channeling and dead zones since you dont want your live rock sitting on the sand and blocking water flow through the bed.

I was going to ask about this but saw the pic in the gallery with your liverock on little pvc risers.

Doug

 

[Shoestring Reefer]

This also relates to why I asked what the actual downfall of DSB really is. I know this has been debated, and some people say it is accumulation of phosphates leading to an algae bloom that consumes oxygen and basically suffocates other inhabitants in the tank. Others say it is accumulation of heavy metals that eventually gets to toxic levels leading to mass die-off. Others think the DSB is not diverse enough or large enough to support enough critters to efficiently recycle materials, leading to buildup and eventual crash of the sandbed.

There are many (and long) threads on DSBs, as you must have read (at least partly) based on your post. I've read probably 120 or more pages on DSBs lately, and I get the impression that it's not heavy metals and massive die-offs (not that heavy metals are not a concern) but phosphate problems seem (based on other people's posts) to happen first, and die-off is not often reported.

One suspected cause is that the bacteria fix phosphate, and as the anoxic region moves up through the bed, the aerobic bacteria die and their retaned phosphate is released. This is debatable, but it's the theory that jives with me, FWIW.

 

[Shoestring Reefer]

Your first post states in the description of your tank you are using a 5 inch sandbed of coarser media than usually recommended for a DSB. Later you state it is between 3 and 4 inches.

You state you are using Carib Sea Special Grade Sand, which was later said to be approximately 1 mm (10x coarser than sugar sand).

"Also, remember I do not believe in using fine sugar sand. I believe it is far to dense and leaves little open area to allow adequate fluid flow. I use a very uniform coarse crushed coral that is designed for exactly what I want. Pore space for fluid movement to reach deep into the bed"


My question to this is what is the difference between using a coarser media 5 inches deep, or using a finer media that is perhaps 2 or 3 inches deep?

The smaller particles will provide much greater surface area for bacterial populations than the coarser media, so should improve the biological filtration.

You will not take up as much viewing area in your tank as a 5 or 6 inch bed if you could use a shallower bed with finer particles. You should still get the oxygen depleted areas without needing the same depth, but could prevent the completely oxygen devoid areas by reducing depth of finer grain substrate so it is not a DSB anymore.

Now I don't know about fluid flow, but wouldn't you be able to get adequate fluid flow through a shallower bed? Also, wouldn't a bed of finer particles help combat the channeling of fluid through an area of least resistance? I would think a coarser media would be more likely to channel, since the finer material would settle more and be moved around more by the water flow to fill in any channeling that occurs. You state that detritus will block pores in a finer substrate leading to dead zones. Wouldn't a finer substrate result in detritus being caught higher up in the sandbed in the oxic zone, where bacteria and microfauna can get at it? As opposed to it being sucked down so far into the coarser bed in an anoxic zone etc?

Using the finer substrate would also allow for people to keep the sandbed fauna that people want to assist with cleanup and recycling of wastes in the form of food organisms, or just for the novelty of having those different critters. Wouldn't sandbed stirrers also prevent the dead zones since they would stir up finer sands that would break up any clogging.

This is why I was asking about the depth of the bed, and possible use of finer sand substrate.

You stated your opinion that you would use a coarser media, but I don't understand why a shallower bed of finer media would not also be affective. Can't you get water to flow through the bed of finer material? Can't you get the same pressure drop by using smaller holes in the PVC pipe? Or would you need a longer drop for the siphon tube to increase pressure drop through a fine sand bed?

I'll throw my 0.02 in again, because I'm trying to get 100 posts a week rather than per month, so here goes:

I must agree with ldrhawke that bigger is better. Bigger particles will be less likely to trap detritus in one place; rather, detritus will be more able to simply pass through.

Some of this detritus will be removed from the system, and never get broken down, so IMO more surface area for bacteria is not required. You won't need to break it down, because it's getting flushed out.

 

[ldrhawke]

Hello,

.........Your first post states in the description of your tank you are using a 5 inch sandbed of coarser media than usually recommended for a DSB. Later you state it is between 3 and 4 inches.

...........................You state you are using Carib Sea Special Grade Sand, which was later said to be approximately 1 mm (10x coarser than sugar sand).

..............My question to this is what is the difference between using a coarser media 5 inches deep, or using a finer media that is perhaps 2 or 3 inches deep?

The smaller particles will provide much greater surface area for bacterial populations than the coarser media, so should improve the biological ........................................................................................................................... but I don't understand why a shallower bed of finer media would not also be affective. Can't you get water to flow through the bed of finer material? Can't you get the same pressure drop by using smaller holes in the PVC pipe? Or would you need a longer drop for the siphon tube to increase pressure drop through a fine sand bed?


I asked about whether there were solid components to the waste that builds up in the sandbed that we should be concerned with. I don't see this really being addressed in this thread besides you stating that the bacteria should eat everything and it will all be in solution. I think more measurments on the contents of your wastewater, vs what you are adding in the way of food and salt etc should be done. Try to correlate inputs to outputs, that way you will see what is building up possibly in your system. Some things will be incorporated into biomass of fish and corals, but other things are probably still accumulating and filling in your coarse sandbed like any other DSB. The question is... what?

Have you done any sampling of your bed, like a core sample so you can check for accumulating solids and preciptates?

The waste water you are throwing away, is it a higher concentration of heavy metals like copper? Or are these still possibly accumulating in your system so that after a 2 year period, you will have a crash just like DSB? Long term data would help show possible things to be concerned with.

This also relates to why I asked what the actual downfall of DSB really is. I know this has been debated, and some people say it is accumulation of phosphates leading to an algae bloom that consumes oxygen and basically suffocates other inhabitants in the tank. Others say it is accumulation of heavy metals that eventually gets to toxic levels leading to mass die-off. Others think the DSB is not diverse enough or large enough to support enough critters to efficiently recycle materials, leading to buildup and eventual crash of the sandbed.

From reading what you have stated, my interpretation is that you
believe that drawing water off from low in the sandbed will resolve the crashing of DSB, but why? Your proof that your system is working is the lack of rotten-egg smell in the waste water, meaning less hydrogen sulfide in the waste water.

I would like to see more testing over time of what is being drawn
off in your waste water, as well as testing to see if there is
anything still accumulating within your coarser bed.


I asked about possiblities of buildups in the pipes because that is
something that would eventually lead to having to tear down the
system, which would be a complete overhaul of a tank since you
are covering the entire bottom with the PVC tubing.
Since you have different PH in the water that is sitting in the tubes, and then flushing them and filling them with water of a different PH which will sit for hours/days etc, the water parameters will change while the stuff sits in the pipe. Since PH can drop over time, could this lead to salts or other precipitates that will accumulate in the pipe and eventually lead to failure? Again, without long term data to see if the pipes fail over time because of buildup, people are going to be skeptical of claims that your suggestion will fix long term problems with only short term data.


You also state you are using 1/2 pvc with 1/32 inch holes drilled
approximately every 2 inches. The only people I see who made suggestions for orientation of the drain holes in the PVC were Shoestring Reefer and Borecki. Do you drill the holes, on top, bottom, or side of the pvc, or all the way around the circumference of the pipe.


Sorry for the lengthy post, but my questions were not from a lack of reading... lack of understanding yes.

____________________________

Measured 3.5" front and 5" rear.

Carib Sea Special Grade is 1 to 1.7mm. It's listed in their literature.

You have asked a lot of good questions. Many of which you could have answer before asking, or have little real importance, or you know there is no answer for yet, the are what I call the " how high is up questioning approach". Since you read what I have written, you and knew the extent of my testing before even asking the questions.

Not to be a smart a**, but a lot your questions are posed as if I am on your pay roll and you are demanding I prove and verify everything I say, and then report to you. I am just presenting an idea that I think the community can benefit from. I stated numerous times that a lot of testing needs to be done to fine tune the concept of CPW.

Any person so opinionated and able to write such a long dissertation on the high biological value of fine sand should be able to verify and answer a few questions for me, support such an eloquent long list.

Most all of all of your questions are based on your belief that fine sand is better than coarse sand. I like to see some support data for fine sand.

What is the minimum, maximum , and average grain size of the fine sand you purpose? How deep is the fine sand bed? What is the flow rate through your fine sand? What is the pressure drop per inch of depth? At what point and mm size do you consider the fine sand too fine? What is the pore space between the fine sand particles? How long a life to you get before blinding occurs? At what mesh size do you consider your fine sand a clay*? How long have you tested fine sand in the bottom of you tank? Hve you tested it with a plenum underneath? What was your biological loading during the test? Does calcification cause blinding in your fine sand now? Do you think you will have more or less binding with flow through the bed? How do you know you have more active bacteria on fine sand? Have bacteria counts at various depths and over an extended period been done to evaluate life support. At what depth in the fine do you find anoxic conditions? What is the pH at various depths? Have you measure the nitrates and phosphate concentrations in the bottom of your present tank? What is your present set up and how long have you been using it.

Sorry, I don't have all the answers either.


Easy to ask a lot of questions.

These are good questions also. What are your answers? You answer these and then I'll attempt to answer yours.

*Clay is often used as an impermeable ground seal layer for ponds.