That's very useful to know, thanks!
Algae Scrubber Basics
- Thread starter srusso
- Start date
That's very useful to know, thanks!
SantaMonica
Well-known member
Actually it's about getting a turbulent air/water interface to the strands. This comes from Adey's book and studies. When an algal strand passes through a bubble, you get this (the strand goes from wet to "dry" to wet again.) Works great.
Floyd R Turbo
Either busy or sleeping
Who said that an algae strand passes through a bubble? Was that you, or Adey?
Floyd R Turbo
Either busy or sleeping
I've got Dynamic Aquaria. Point me to the section where he says that an air bubble causes a wet/dry/wet effect. Because logically speaking, this doesn't make any sense. The air/water interface I believe he discusses is related to the dumping and/or surging action and the algae actually getting physically exposed to air, not an air bubble passing through a submerged algal mass, but correct me if I am wrong. That book is a textbook so it's not something one can sit down and just read without a few cans of Jolt.
A bubble has surface tension. If an algal strand were to have a bubble travel past it, the strand would just get pushed out of the way as the bubble passes. While this creates a rapid movement of the algal strand, it just doesn't make sense that the bubble is pierced by the strand, because it has no rigidity. I could put a paper clip above an air outlet and that would slice a bubble in half, but not every bubble - any bubble that came up off-center would stand a chance of actually moving around it as well. So how could an algal strand, a flaccid mass, actually penetrate the surface tension of a passing bubble? You're going to have to prove this one to me, because I just don't buy it.
Now, if you have a mass of algae (in a UAS) that is essentially ready to harvest from compacted growth as a result of growing in a restricted chamber, and you pass an air bubble through it, it might cause an air pocket where algal growth remains exposed for a time period, but this would be at the top of the growth enclosure, and this situation specifically excludes all open scrubbers. The path of the air bubble in a restricted growth chamber full of growth would be somewhat inhibited (slowed down) and I could see a case by where the bubble could get sliced up, but for the most part the algae will not grow into the path of the bubble, and will actually grow around the path of the bubble (meaning, the growth will be restricted near the "air channel"). On top of that, a freshly cleaned scrubber would allow for free passage of said bubbles, and then we're back to the algae strands moving out of the way.
I never have bought into this theory of yours that defines the air bubble wet/dry/wet interface because of these above reasons. Rapid, random motion created by bubbles, yes, I think that makes logical sense but I still don't think it's an improvement over a thin rapidly falling sheet of water, it's just a different way to do it and it creates a solution for many people who otherwise would not have the ability to use a scrubber.
I would bring this up to you on your site but you banned me and many others for asking such questions. You probably have me blocked/ignored on here too. But there it is for the world to see. I'm totally open to changing my opinions about the bubble theory if you can prove it to me.
A bubble has surface tension. If an algal strand were to have a bubble travel past it, the strand would just get pushed out of the way as the bubble passes. While this creates a rapid movement of the algal strand, it just doesn't make sense that the bubble is pierced by the strand, because it has no rigidity. I could put a paper clip above an air outlet and that would slice a bubble in half, but not every bubble - any bubble that came up off-center would stand a chance of actually moving around it as well. So how could an algal strand, a flaccid mass, actually penetrate the surface tension of a passing bubble? You're going to have to prove this one to me, because I just don't buy it.
Now, if you have a mass of algae (in a UAS) that is essentially ready to harvest from compacted growth as a result of growing in a restricted chamber, and you pass an air bubble through it, it might cause an air pocket where algal growth remains exposed for a time period, but this would be at the top of the growth enclosure, and this situation specifically excludes all open scrubbers. The path of the air bubble in a restricted growth chamber full of growth would be somewhat inhibited (slowed down) and I could see a case by where the bubble could get sliced up, but for the most part the algae will not grow into the path of the bubble, and will actually grow around the path of the bubble (meaning, the growth will be restricted near the "air channel"). On top of that, a freshly cleaned scrubber would allow for free passage of said bubbles, and then we're back to the algae strands moving out of the way.
I never have bought into this theory of yours that defines the air bubble wet/dry/wet interface because of these above reasons. Rapid, random motion created by bubbles, yes, I think that makes logical sense but I still don't think it's an improvement over a thin rapidly falling sheet of water, it's just a different way to do it and it creates a solution for many people who otherwise would not have the ability to use a scrubber.
I would bring this up to you on your site but you banned me and many others for asking such questions. You probably have me blocked/ignored on here too. But there it is for the world to see. I'm totally open to changing my opinions about the bubble theory if you can prove it to me.
thejuggernaut
Member
I just thought the air was a way of creating water movement up the water column. Just like they use to do with undergravel filters and air stones.
avandss
I'm hooked
same here
Floyd R Turbo
Either busy or sleeping
Yes, water motion is the primary need of a scrubber, and bubbles rising provided this. Bubbles rising also create localized rapid water motion which can break down the boundary layer. Not denying that, that makes logical sense. I'm challenging the wet/dry/wet theory.
avandss
I'm hooked
dont get me wrong, i agree with what you are saying 100%
Floyd R Turbo
Either busy or sleeping
No, I didn't get you wrong 
thank you both for bringing that up - so I was sort of putting an addendum on my statement
thank you both for bringing that up - so I was sort of putting an addendum on my statement
herring_fish
Crazy Designer
OK "¦I drank the Jolt, the Red Bull, and did the Dew. I read it from cover to cover and the point of the dump bucket is the water surge. The point of the surge is to reduce clumping. That means breaking down boundary layers, keeping individual strands separate, having moments of high energy which better insures that water gets to the algal cell walls. Of course there are other benefits like solar flashing and much more but to start the first of a broken record, it's about getting water to the cell wall.
Yes bubbles can promote turbulence but not as much as high energy, irregular water movement. Adey's point was that algae evolved in the tidal zone to cope with areas of very high energy and high predation. Fast growth was an adaptation to high shear forces and grazing. Fast growth is why algae is what we grow in our scrubbers. Requirements for a fast metabolism are nutrients and CO2 from water and lots of light.
The algae's that Adey proposes using, grows IN the water and not an algae that grows just out of the water where it is kept wet by splashing. After all, above the water line, there is more air and more light but that is not where it like to grow fastest. That is also why he proved through numerous studies that turf algae grows fastest.
In our low energy scrubbers, sometimes turf algae doesn't do as well as the long stuff that we like but a low energy scrubber is not the most efficient per square inch of screen surface. That doesn't mean that they don't work. It just means that you have to get the right sized unit to do the job and the effect will be the same. The problem is that high energy scrubbers are harder to design and produce.
"¦.but the point is insuring that water gets to as many cell walls as possible because that is what it wants. Air displaces water. Our reason for having a scrubber so that water is stripped of nutrients right? You can't absorb waist from air. Algae has adapted to getting CO2 from water not air bubbles.
If you don't have as much turbulence as you would like, you will need to harvest before clumping has a chance to occur. Aside from that, good water movement is what you need.
I guess that I will post plans for a true Adey dump bucket style Algal Turf Scrubber. This was patent protected until recently. You will see that making one is no picnic, but if you are designing a scrubber, just get as much as you can of the big three.
1. Get enough good surface area as you can.
2. Provide enough good quality light.
3. Facilitate good water contact with the algae strand cell walls.
If you have that you should be good.
Yes bubbles can promote turbulence but not as much as high energy, irregular water movement. Adey's point was that algae evolved in the tidal zone to cope with areas of very high energy and high predation. Fast growth was an adaptation to high shear forces and grazing. Fast growth is why algae is what we grow in our scrubbers. Requirements for a fast metabolism are nutrients and CO2 from water and lots of light.
The algae's that Adey proposes using, grows IN the water and not an algae that grows just out of the water where it is kept wet by splashing. After all, above the water line, there is more air and more light but that is not where it like to grow fastest. That is also why he proved through numerous studies that turf algae grows fastest.
In our low energy scrubbers, sometimes turf algae doesn't do as well as the long stuff that we like but a low energy scrubber is not the most efficient per square inch of screen surface. That doesn't mean that they don't work. It just means that you have to get the right sized unit to do the job and the effect will be the same. The problem is that high energy scrubbers are harder to design and produce.
"¦.but the point is insuring that water gets to as many cell walls as possible because that is what it wants. Air displaces water. Our reason for having a scrubber so that water is stripped of nutrients right? You can't absorb waist from air. Algae has adapted to getting CO2 from water not air bubbles.
If you don't have as much turbulence as you would like, you will need to harvest before clumping has a chance to occur. Aside from that, good water movement is what you need.
I guess that I will post plans for a true Adey dump bucket style Algal Turf Scrubber. This was patent protected until recently. You will see that making one is no picnic, but if you are designing a scrubber, just get as much as you can of the big three.
1. Get enough good surface area as you can.
2. Provide enough good quality light.
3. Facilitate good water contact with the algae strand cell walls.
If you have that you should be good.
Floyd R Turbo
Either busy or sleeping
I recall reading that true turf algae is actually much more efficient, but like you said, building the device that perfects growing turf algae is much more difficult, but probably more suitable for certain systems, namely very large systems.
Thanks for the post HF - very informative. I seen things I can gleam off for my next "basics" update...
Thanks for the post HF - very informative. I seen things I can gleam off for my next "basics" update...
herring_fish
Crazy Designer
Yes They are big and don't have the best shape. There is also the splashing sound. With another design you can simply make up for efficiency per square inch by increasing the square inches.
This is a re-post from another thread on RC. I have held off on posting this for a long time. I didn't want to get in the way of the general thrust of information but some people will find it interesting.
PLEASE DO NOT TRY TO BUILD ONE OF THESE FROM MY PLANS!
Some fine points of the design were changed after the CAD work was completed, during construction.
THESE PLANS ARE FOR REFERENCE ONLY!
You would have to have fabrication knowlege, skills and the proper equipment.
These are some of the ATS’s that Dr. Adey suggested that worked best because of the agitation and turbulence that they produce. Good turbulence increases effectiveness by 50% and greatly reduces clumping which can cause yellowing at the root and die off. Most were about 4 by 8 feet in size and had 1000 watt metal halides
This is my first version. It worked very well but I moved on to the version 2 below.
This is a 3-D PDF of version one. It is NOT to scale but you can rotate it around to see how I laid it out.
Note: Open these in a session of Abode Reader for full features. Click on the link and it will open in your web browser but you will not be able to rotate the model. "Save As" it to your Desk Top or somewhere you can find it. If you already have Adobe Reader then you can open it right away. If you don't have it, go to the Adobe web site and down load it for free. Be sure to look at the other pages that are attached for more information(in the left dark grey margin). Turning the background color to gray will make it easier to see. There is a quickly drawing in version two but you can also go to >Tools>Analysis>Measure to get sizes.
http://asaherring.com/reef/hardware/DumpBucketTriangle.pdf
This is a 3-D PDF of version 2.
http://asaherring.com/reef/hardware/DumpBucket.pdf
By the way, my Avatar is a rendering of the splash from my dump bucket when it was mounted right on top of my 180 gallon tank.
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thejuggernaut
Member
So I guess he point is to have the water flow change directions to change the direction of the algae so that more of the strand is objected to the light? If so a vertical scrubber with a motorized belt system with water on both sides would create a system that allowed water to flow over the algae from both sides.
Floyd R Turbo
Either busy or sleeping
I've seen the motorized drum idea in a few places, but I've never really seen it followed up on. I think it comes down to simplicity, more moving parts mean more things that can go wrong, more complications.
Google "Algae Wheel" for some fun reading
The alternation of light and dark might have some effect, hard to say without actually trying it. But I think it would be along the lines of diminishing returns.
At one of our fests I was discussing algae scrubbers with one of the speakers, who told me that the dump bucket scrubber works so well because of the back and forth motion having the effect of keeping strands separated and exposing both sides of the algae to the light. He poo-pooed the idea of the waterfall scrubber because of this knowledge he had. When I asked him if he had ever used a waterfall scrubber, he said no - in fact, he had never even seen one in person. I lost a lot of confidence in his opinion at that moment.
My point is that static scrubbers work just fine in the vast majority of cases, and of course there is a trade-off between factors like efficiency, complexity/simplicity, cost, space, etc.
What I think would be a good cross-over would be to have a waterfall scrubber combined with a surge device. Picture an enclosed waterfall scrubber, with a surge inlet on the side or bottom that periodically fills the box (rapidly) and then drains out quickly and the waterfall continues.
I've seem waterfall scrubbers where they let the box fill and then drain it quickly - that's not what I'm talking about, IMO that is very inefficient, because you need rapid water motion all the time. Waterfall + reverse surge would be very interesting. I've had that idea in my head for years, but haven't ever had the chance to try it. Again, complicated.
Google "Algae Wheel" for some fun reading
The alternation of light and dark might have some effect, hard to say without actually trying it. But I think it would be along the lines of diminishing returns.
At one of our fests I was discussing algae scrubbers with one of the speakers, who told me that the dump bucket scrubber works so well because of the back and forth motion having the effect of keeping strands separated and exposing both sides of the algae to the light. He poo-pooed the idea of the waterfall scrubber because of this knowledge he had. When I asked him if he had ever used a waterfall scrubber, he said no - in fact, he had never even seen one in person. I lost a lot of confidence in his opinion at that moment.
My point is that static scrubbers work just fine in the vast majority of cases, and of course there is a trade-off between factors like efficiency, complexity/simplicity, cost, space, etc.
What I think would be a good cross-over would be to have a waterfall scrubber combined with a surge device. Picture an enclosed waterfall scrubber, with a surge inlet on the side or bottom that periodically fills the box (rapidly) and then drains out quickly and the waterfall continues.
I've seem waterfall scrubbers where they let the box fill and then drain it quickly - that's not what I'm talking about, IMO that is very inefficient, because you need rapid water motion all the time. Waterfall + reverse surge would be very interesting. I've had that idea in my head for years, but haven't ever had the chance to try it. Again, complicated.
Lavoisier
Premium Member
Indeed, which hundreds (thousands) of us can attest to. Thanks, Floyd, for all your great work on these threads. :beachbum:
herring_fish
Crazy Designer
Yes ....That is an added benefit but the main point is forcing the individual strands apart (like a comb), breaking down boundary layers, getting higher surges of water flow as opposed to a constant rate. Light can go right through individual strands of algae but a mat of algae obstructs light as well as restricting direct water exposure to the strand walls. Water surges act like a comb to keep algae from matting.
Rastafarian hair may be stylish but clumped and matted algae …even just a little bit of it, is bad. Meticulously prompt harvesting can insure that this doesn’t happen in any design, with or without surge.
Solar flashing can happen any time wave action happens and is not limited to surge devices. Waves can focus light into single spots or balls of light, sometimes called glitter lines. Studies going back as far as the time of the First World War indicate that brief intense flashes of light can foster more growth than the same amount of light spread out into a constant exposure. 10 to 40 percent light and the rest dark time works best. Also we are learning through LED research that, if light has different wave lengths included in it, slight separation of time between the different colors will also help. Once again, this requires more complicated equipment and would yield small improvements. Of course this can be produce without surge or wave action at all.
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Floyd R Turbo
Either busy or sleeping
I'll pick your brain for an opinion on the clumped and matted algae issue.
When running T5HO scrubbers in the past, I had to clean them every 7 days, maybe 10, but if I ever went over that, I ended up with dead roots.
With the LED scrubbers I run, I've found that this is not an issue. I recently got a bit lax in my rounds and let 2 scrubbers grow from 11/10 until 11/29 - 19 days between cleanings. On both scrubbers, the algae was still firmly attached, no lower layer death, and holes still filled in just as much as they are at the normal 14 day cleaning.
The spec of these are that the LEDs are 660nm, 2" on center, and 2" distance from the growth, in an enclosed growth box. I also run a light/spray blocker over the slot pipe which I have found keep the slot/screen junction nearly 100% algae free, so there is no reduction in flow rate over the whole growth period...at least, not significant when compared to flow rate when I wasn't using these. The growth does get to the point where it starts to attach to the light blocker, but it still doesn't appear to impede flow - in fact, that may drive flow more down the middle of the screen as the algae grows outward.
So anyways, I kind of went off on a tangent there but I wanted to give the whole picture.
My thought is that the time of the past dealt with 1000W MH and horizontal surge scrubbers, but I would put it out there that these experiments that determined that this surging was completely necessary might need to be revisited, because of the advent of LED light. LEDs really do seem to penetrate very deep into the substrate, when placed in the right proximity and operated at the right time and intensity, so much so that I think enough light penetrates down through the clumped/matted masses to sustain growth (or at least, prevent decay) of algae deep with the mass.
This may be influenced by the device (the "3D growth box") or it may also be a general rule for LED, giving it at least some kind of advantage over other sources in general.
Still, for a horizontal scrubber, I would think that the surge is still beneficial to discourage channeling and other things - again, the surge is needed for horizontal, but may not be for vertical/enclosed with LED source, and that is the difference between then and now which has not been truthfully and scientifically revisited.
When running T5HO scrubbers in the past, I had to clean them every 7 days, maybe 10, but if I ever went over that, I ended up with dead roots.
With the LED scrubbers I run, I've found that this is not an issue. I recently got a bit lax in my rounds and let 2 scrubbers grow from 11/10 until 11/29 - 19 days between cleanings. On both scrubbers, the algae was still firmly attached, no lower layer death, and holes still filled in just as much as they are at the normal 14 day cleaning.
The spec of these are that the LEDs are 660nm, 2" on center, and 2" distance from the growth, in an enclosed growth box. I also run a light/spray blocker over the slot pipe which I have found keep the slot/screen junction nearly 100% algae free, so there is no reduction in flow rate over the whole growth period...at least, not significant when compared to flow rate when I wasn't using these. The growth does get to the point where it starts to attach to the light blocker, but it still doesn't appear to impede flow - in fact, that may drive flow more down the middle of the screen as the algae grows outward.
So anyways, I kind of went off on a tangent there but I wanted to give the whole picture.
My thought is that the time of the past dealt with 1000W MH and horizontal surge scrubbers, but I would put it out there that these experiments that determined that this surging was completely necessary might need to be revisited, because of the advent of LED light. LEDs really do seem to penetrate very deep into the substrate, when placed in the right proximity and operated at the right time and intensity, so much so that I think enough light penetrates down through the clumped/matted masses to sustain growth (or at least, prevent decay) of algae deep with the mass.
This may be influenced by the device (the "3D growth box") or it may also be a general rule for LED, giving it at least some kind of advantage over other sources in general.
Still, for a horizontal scrubber, I would think that the surge is still beneficial to discourage channeling and other things - again, the surge is needed for horizontal, but may not be for vertical/enclosed with LED source, and that is the difference between then and now which has not been truthfully and scientifically revisited.
herring_fish
Crazy Designer
As you well know, I am not an expert. I’m just a designer that read the book and has used scrubbers for a long long time.
The water fall scrubber is nice and inexpensive and there for may have done a lot for scrubbing in general because of how much market penetration that has resulted from its development. It is not the most efficient per square inch but it has more inches. You do have to be careful with your harvest schedule but into fits in tight spaces.
That being said I personally think that your 3-D design is an improvement over the water fall scrubber but it is harder to build. If you have the fabrication skills to make it or you can by it, you will have a generally better scrubber but that is just my opinion. I would think that 3-D growth reduces matting because the water flow does not actually cause the strands to lie down. Algae can grow away from the screen and not be push down and flatten.
Adding the LED lighting is another layer of improvement that undoubtedly benefits 3-D scrubbers whether they are in a bucket or not, as well as non 3-D scrubbers whether they have a surge or not.
For any scrubber, matting can be an issue that will eventually crop up, no matter what the design is. I also would think that surge lengthens that time a little but is that the most important thing?
Again, clumping reduces water contact with cell walls and therefore respiration which probably is worse than lighting that is only cut in half.
I know that I went 3 months when I was on the road and saw no die off but if you want to harvest every week or so is that worth the splash sound, size and shape? I like dump buckets but most well designed scrubbers do the exact same thing, don’t they? They just have different upsides and downsides but they all work.
The water fall scrubber is nice and inexpensive and there for may have done a lot for scrubbing in general because of how much market penetration that has resulted from its development. It is not the most efficient per square inch but it has more inches. You do have to be careful with your harvest schedule but into fits in tight spaces.
That being said I personally think that your 3-D design is an improvement over the water fall scrubber but it is harder to build. If you have the fabrication skills to make it or you can by it, you will have a generally better scrubber but that is just my opinion. I would think that 3-D growth reduces matting because the water flow does not actually cause the strands to lie down. Algae can grow away from the screen and not be push down and flatten.
Adding the LED lighting is another layer of improvement that undoubtedly benefits 3-D scrubbers whether they are in a bucket or not, as well as non 3-D scrubbers whether they have a surge or not.
For any scrubber, matting can be an issue that will eventually crop up, no matter what the design is. I also would think that surge lengthens that time a little but is that the most important thing?
Again, clumping reduces water contact with cell walls and therefore respiration which probably is worse than lighting that is only cut in half.
I know that I went 3 months when I was on the road and saw no die off but if you want to harvest every week or so is that worth the splash sound, size and shape? I like dump buckets but most well designed scrubbers do the exact same thing, don’t they? They just have different upsides and downsides but they all work.
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thejuggernaut
Member
I get your point about balancing simplicity and effectiveness. No point adding allot more complexity and motorized belt drives if it only gets you 10% better results.
SantaMonica
Well-known member
No, it's primarily to deliver the turbulent air/water interface to the algae. Very little delivery "turnover" of water itself is needed, because algae only absorbs a small percentage of nutrients per pass, similar to eating at a buffet: you can only eat so much; having more food there will not allow you to eat more (you'll have to come back every few hours to eat the whole thing).
That's why water needs hundreds of passes through a scrubber to remove sufficient nutrients; because only a small amount of nutrients are removed each pass. The algae does not even touch any of the water outside of the microscopic boundary layer, so adding more water outside of that does nothing.
That's why upflow versions with strong bubbles can pack with algae when there is only small holes to allow for water flow.
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