DSB Heresy
- Thread starter ldrhawke
- Start date
thriceanangel
Active member
I have been toying with the idea for my next tank - 48" cube and didn't know this thread existed.
I will use 4 -6" intakes below the sand, and 2 2" intakes above the sand all on a closed loop. The idea is that the large intakes below the sand will slowly but continously flow water through the sand and plenum through a semi-closed loop. For more information on this design, check this link:
http://fingerlakesreef.com/forum/viewtopic.php?p=9411#9411
I will use 4 -6" intakes below the sand, and 2 2" intakes above the sand all on a closed loop. The idea is that the large intakes below the sand will slowly but continously flow water through the sand and plenum through a semi-closed loop. For more information on this design, check this link:
http://fingerlakesreef.com/forum/viewtopic.php?p=9411#9411
I would read the thread & you will see that ldrhawke tried to re introduce the waste water back into the system also. This sounds similar to what you have in mind, a closed system. Big Daddy who resurrected this thread has had no problems so far ( 3 yrs ) with this CPW system with just draining & discarding the waste
I have built a similar plenum, but not to the design that Iderhawke has. Mine use's a cross piece at several sections (4 way pvc fitting) this enabled me to install it in sections because of the euro brace. I did opt for the screen instead of the drainage cloth, simply for a better flow with less restriction over time JMO.
I do believe that just draining & discarding the waste water is the better option.
I have been researching this Plenum / CPW plenum for quite some time now & have found a member who has been using a plenum in excess of 11 years with excellent results from the start.
This is my first attempt at this but after all the research I have done & the members that I have been in contact with about a plenum system, it looks promising to just keep the DSB cleaner & not be the eventual dump it will develop in to over time.
I hope to post some posotive results on this in the future
Steve 926
:smokin:
pjf
Premium Member
The main contributor experimented with more than just the bare bottom approach. Apparently, one of his last posts in June of 2005 was in response to a fellow RC member. Someone asked him:
"Can you give us a full description of your path from plenum draining thingy, to bare bottom, to vodka, to zeo? That seems like a lot of methodology changes in a short amount of time. I'd be interested in knowing how you determined how each wasn't working and why the switch to the next and how long before you determined each wasn't working."
The thread was entitled, "Can we talk about Zeo, if we promise to be civil?" I'm not sure how civil everyone was or which methodology he finally settled on but the rest is history.
"Can you give us a full description of your path from plenum draining thingy, to bare bottom, to vodka, to zeo? That seems like a lot of methodology changes in a short amount of time. I'd be interested in knowing how you determined how each wasn't working and why the switch to the next and how long before you determined each wasn't working."
The thread was entitled, "Can we talk about Zeo, if we promise to be civil?" I'm not sure how civil everyone was or which methodology he finally settled on but the rest is history.
carlso63
Reefkeeping since 1977
Not sure if this is significant to this thread (or not) -
I have run plenumed systems for many years (decades) now... the longest-running plenumed system I have run was a 175g display w/ a full plenum made of eggcrate / screening held up off the bottom by 1" PVC sections. Two substrate layers (med. coarse and very fine) themselves seperated by a 2nd screening. Total sandbed depth was about 4.5 -5" (plus another 1.25" for the plenum)...
In addition to the plenum the system had maybe 125 lb. of LR, a 50g sump and a 15g refugium to aid in filtration...
System was a "Mixed" Reef containing LPS and SPS along with a few "soft" corals, anenomes, etc and a modest fish load.
The system was set up in March of 1991 and was finally dissasembled Thanksgiving weekend, 2002 because we were moving from LI, NY to Utah (job transfer) so it ran a little more than 11.5 years, uninterrupted... without a "crash", ever. I did do partial water changes (usually 10g every 2 weeks) and dosed some trace elements at usually 1/6 the recommended dose for the water volume, and only about once every month or two...
Never had any measurable nitrates after the 90-day mark (approx); upon disassembly there were no 'dark' pockets (HS2) to be found.
Never added any pods or "critters" of any sort to the sandbed; relied on macroalgae "trimming" from the refugium for any nitrate / phosphate exporting...
No question in my mind that plenums work long-term. Period. (Although this 'CPW' is an interesting concept)...
I have run plenumed systems for many years (decades) now... the longest-running plenumed system I have run was a 175g display w/ a full plenum made of eggcrate / screening held up off the bottom by 1" PVC sections. Two substrate layers (med. coarse and very fine) themselves seperated by a 2nd screening. Total sandbed depth was about 4.5 -5" (plus another 1.25" for the plenum)...
In addition to the plenum the system had maybe 125 lb. of LR, a 50g sump and a 15g refugium to aid in filtration...
System was a "Mixed" Reef containing LPS and SPS along with a few "soft" corals, anenomes, etc and a modest fish load.
The system was set up in March of 1991 and was finally dissasembled Thanksgiving weekend, 2002 because we were moving from LI, NY to Utah (job transfer) so it ran a little more than 11.5 years, uninterrupted... without a "crash", ever. I did do partial water changes (usually 10g every 2 weeks) and dosed some trace elements at usually 1/6 the recommended dose for the water volume, and only about once every month or two...
Never had any measurable nitrates after the 90-day mark (approx); upon disassembly there were no 'dark' pockets (HS2) to be found.
Never added any pods or "critters" of any sort to the sandbed; relied on macroalgae "trimming" from the refugium for any nitrate / phosphate exporting...
No question in my mind that plenums work long-term. Period. (Although this 'CPW' is an interesting concept)...
Daemonfly
New member
Here's a question:
What actually collects in the plenum? Sediment or is it just nasty water?
If it's any kind if sediment, would a small closed-loop filter work to help remove it? Say, a small cannister filter, or DIY floss filter. This would only take water from the plenum, then return it to the plenum, no interaction with anything above the sandbed.
What actually collects in the plenum? Sediment or is it just nasty water?
If it's any kind if sediment, would a small closed-loop filter work to help remove it? Say, a small cannister filter, or DIY floss filter. This would only take water from the plenum, then return it to the plenum, no interaction with anything above the sandbed.
thriceanangel
Active member
The plenum contains nothing but water, and tiny particles of detritus that will be blown back into the system before they can actually collect to any significant level. Then they will be flitered out by the mechanical filtration that is employed by the rest of the system.
In ldrhawke, the water was discarded because it was a conversion to an already established system. There was already nasty stuff at the bottom, and the sand was already dirty. This would be a totally new system, so there would be no buildup, or chance for the nasty stuff to collect. At first ldrhawke describes a rotten egg smell that went away after a few weeks. That wouldn't be the case. The bacterium would establish themselves in this system from the getgo. It is what I would call partially closed because once a week I will do a water change as always, BUT I will use the below the sand intakes to get the water that will be changed. So in that sense, it will get drained. Just not as often.
In ldrhawke, the water was discarded because it was a conversion to an already established system. There was already nasty stuff at the bottom, and the sand was already dirty. This would be a totally new system, so there would be no buildup, or chance for the nasty stuff to collect. At first ldrhawke describes a rotten egg smell that went away after a few weeks. That wouldn't be the case. The bacterium would establish themselves in this system from the getgo. It is what I would call partially closed because once a week I will do a water change as always, BUT I will use the below the sand intakes to get the water that will be changed. So in that sense, it will get drained. Just not as often.
This is an interesting concept to the CPW design.
Basically then you are using the sand bed as a continuous sand filter, & draining a portion of the detritus from it during a water change, if I understand it correctly ?
So in essence a smal pump connected to the CPW design may accomplish a similar result
Please post your results when you decide to try this.
Steve 926
:smokin:
thriceanangel
Active member
yes, but it's a DSB so hopefully the oxygen will get used up on its way down.
It's not a small pump. The slow flow is created by two things:
1. An extremely large diameter intake multiplied X 4: 4 six inch intakes, so even with a large pump the flow will be slow. Think 1000gph through a sluice pipe, vs a straw
2. The closed loop flow will be divided between the 4 intakes below the sand, and 2 x 2" intakes above the sand. Naturally the water takes the path of least resistance, so most of it will flow through the above sand intakes, even lessening the amount flowing through the large under sand intakes which will be impeded by the sand, and screen, and the water that does flow through them will be lower velocity due to the large diameter.
I will be able to adjust the flow using valves to achieve the optimum flw through each intake system. And I'll be able to maintain the flow by being able to clear any obstructions by the back flow created when the pump is shut down after completing a water change... at least thats the plan. (crossing fingers)
Fairly complicated to write about, but it seems easy to understand in my head. The principals are farily straightforward though. The hard part will be getting the flow dialed in so that enough is flowing through the sand, but not too much to make it well oxygenated.
It's not a small pump. The slow flow is created by two things:
1. An extremely large diameter intake multiplied X 4: 4 six inch intakes, so even with a large pump the flow will be slow. Think 1000gph through a sluice pipe, vs a straw
2. The closed loop flow will be divided between the 4 intakes below the sand, and 2 x 2" intakes above the sand. Naturally the water takes the path of least resistance, so most of it will flow through the above sand intakes, even lessening the amount flowing through the large under sand intakes which will be impeded by the sand, and screen, and the water that does flow through them will be lower velocity due to the large diameter.
I will be able to adjust the flow using valves to achieve the optimum flw through each intake system. And I'll be able to maintain the flow by being able to clear any obstructions by the back flow created when the pump is shut down after completing a water change... at least thats the plan. (crossing fingers)
Fairly complicated to write about, but it seems easy to understand in my head. The principals are farily straightforward though. The hard part will be getting the flow dialed in so that enough is flowing through the sand, but not too much to make it well oxygenated.
thriceanangel
Active member
So if the intake flow was divided evenly amongst something like the intake specs of a barracuda, it would be only 750 gph per intake. But take into consideration the restrictions of the below sand intakes, and it may be somewhere around 450-550 gph going through each under sand intake. But due to the large intake diameter, the flow would be slow. Might even slow it down further by using a dart instead.
Then I think that it would most definitely be under 300 gph through each 6" intake. - if that.
Then I think that it would most definitely be under 300 gph through each 6" intake. - if that.
Do you have the room to fit all of this without compromising the structural interegity of the bottom plate ( glass / acrylic ) ?
Could be a long & sad evening if it lets go !
It sounds feasible, almost like a UGF or in your case a USF. I wish you the best of luck in your endeavor & hope to hear good results from you in the future.
Steve 926
:smokin:
Could be a long & sad evening if it lets go !
It sounds feasible, almost like a UGF or in your case a USF. I wish you the best of luck in your endeavor & hope to hear good results from you in the future.
Steve 926
:smokin:
thriceanangel
Active member
The bottom is epoxy covered 3/4" poplar plywood, I think that I could drill many more, and add much more weight as well without a problem. It's also supported underneath by 2x4's with angle bracing. Strong enough to hold up a car I'd say... It's really over built.
Here's a pic of the stand
http://fingerlakesreef.com/forum/viewtopic.php?p=4943#4943
taking my time, but it'll get done sooner or later...
Here's a pic of the stand
http://fingerlakesreef.com/forum/viewtopic.php?p=4943#4943
taking my time, but it'll get done sooner or later...
WOW !
Id say a Volkswagen at least
I often thought of building a display & using plywood in some of the design. I would need to see how to attach the plywood to the glass, & in sealing the wood ( epoxy, fiberglass, ? )
Good luck & I anxiously await some pic's ( To copy, steal the design )
Steve 926
:smokin:
Id say a Volkswagen at least
I often thought of building a display & using plywood in some of the design. I would need to see how to attach the plywood to the glass, & in sealing the wood ( epoxy, fiberglass, ? )
Good luck & I anxiously await some pic's ( To copy, steal the design
)Steve 926
:smokin:
thriceanangel
Active member
Wood is sealed with epoxy resin. The glass is glued/siliconed to a plywood frame, it creates a great seal because it's a compression seal. The more water, the better the seal because the water pressure presses on the glass. Typical glass tanks are the exact opposite. More water, pulls the seal apart.
Here is a picture of a friends that is currently for sale.: Mine is similar, but a 48" cube.
Here is a picture of a friends that is currently for sale.: Mine is similar, but a 48" cube.
BigDaddy
Active member
Interesting idea.
I think you will have to test the O2 levels at the bottom of the tank. I was told by draining 5 gallons once every 3 days would disrupt my anerobic bacteria (it didn't) but I do think a few hundred gallon an hour will be too much.
Let us know how it goes.
I think you will have to test the O2 levels at the bottom of the tank. I was told by draining 5 gallons once every 3 days would disrupt my anerobic bacteria (it didn't) but I do think a few hundred gallon an hour will be too much.
Let us know how it goes.
mr.wilson
.Registered Member
I guess I'm missing something?
One method is to rapidly drain the plenum to remove detritus and bacteria; however, detritus doesn't build-up significantly in a plenum, even after years of use. Secondly, why would you want to remove the beneficial bacteria (biofilms) that take so long to form?
The more recent version is a cross between an under gravel filter (UGF) and a reversed under gravel filter (RUGF). It pushes water laterally across the plenum, if I read it correctly. Once again, this is a delicate area that thrives on stability and passive flow. The crux of a denitrifying bed is low dissolved oxygen (DO) rates. Pushing water through this area will reduce the viable sites for denitrifiers (pseudomonas). i.e.. the lower 3" of sand will be just as aerobic as the top 3". You would a need 7" deep sand bed to yield a 1" anaerobic zone suitable for nitrate reduction.
One method is to rapidly drain the plenum to remove detritus and bacteria; however, detritus doesn't build-up significantly in a plenum, even after years of use. Secondly, why would you want to remove the beneficial bacteria (biofilms) that take so long to form?
The more recent version is a cross between an under gravel filter (UGF) and a reversed under gravel filter (RUGF). It pushes water laterally across the plenum, if I read it correctly. Once again, this is a delicate area that thrives on stability and passive flow. The crux of a denitrifying bed is low dissolved oxygen (DO) rates. Pushing water through this area will reduce the viable sites for denitrifiers (pseudomonas). i.e.. the lower 3" of sand will be just as aerobic as the top 3". You would a need 7" deep sand bed to yield a 1" anaerobic zone suitable for nitrate reduction.
thriceanangel
Active member
Thing of it is that when you're removing 5 gals per day, you are only removing the water immediately surrounding what ever intake you have. If my plenum is one inch deep it holds 10 gallons. This also goes on the theory that has been discussed earlier in this thread, that a certain amount of dissolved o2 will not destroy the denitrification of anaerobic denitrifiers. BUT I still am under the assumption that MOST of the water will be drawn from the 2 above sand intakes, slowing the flow through the below sand intakes. I wouldn't say that it rapid draining of the plenum.
I am not opposed to a deeper sand bed either. 7" isn't out of the realm of possibility. However anyone who has removed a sandbed knows that there is TONS of built up gunk down there, am I to believe that just because there is a plenum that there wouldn't be for some reason?
I am not opposed to a deeper sand bed either. 7" isn't out of the realm of possibility. However anyone who has removed a sandbed knows that there is TONS of built up gunk down there, am I to believe that just because there is a plenum that there wouldn't be for some reason?
mr.wilson
.Registered Member
You haven't explained the prupose of removing the 5 gallons, or what you do with it.
I agree that a small influx of oxygen will not harm denitrifying bacteria. In fact, bacteria goes into lag phase where it increases in numbers with environmental changes, such as temperature, salinity, and changes in D.O. levels. It's a natural defense mechanism.
There shouldn't be any "gunk" in the sand, whether you have a plenum or not, even after years of use. Most of the debris in the plenum will be fine sand, with a small amount of detritus. Perhaps you are mistaking this fine sand as "gunk".
There's no problem with a 7" deep sand bed, as long as you have at least 4" of viable anaerobic zone.
The idea of a passive flow through the sand has its' merits. I use a perforated PVC pipe placed vertically in the sand to provide a passive water exchange, and means for nitrogen gas release. A heat source below the sand, such as a refugium light, would be the most efficient means of passive flow. A thermal exchange would occur as the heat rises.
