+ Reply to Thread
Page 1 of 2 12 LastLast
Results 1 to 10 of 14

Thread: Dwell Time, and Plastic Canvas vs. Green Grabber

  1. #1
    Banned
    Join Date
    Aug 2010
    Location
    USA
    Posts
    2,710

    Dwell Time, and Plastic Canvas vs. Green Grabber

    What led me to start this thread was this paragraph on the SURF2 thread http://algaescrubber.net/forums/show...2243#post32243

    Quote Originally Posted by SantaMonica View Post
    A few features of the SURF2 provide real usefulness and are available on no other algae scrubber. First, the enclosed growth compartment increases the dwell time of the water and bubbles inside the unit so that they rub the algae many times before leaving the compartment. This actually reduces nutrients (nitrate, phosphate) to a level lower than the outside water, which allows greener growth to occur sooner (lower nutrients grows greener algae) inside the unit, especially in high-nutrient aquarium water. In other words, the SURF2 creates a lower-nutrient ecosystem inside itself which is different from the rest of the water in your aquarium. Also, the position of the air bubble inlets (below the growth) causes the bubbles to flow through the growth no matter how thick the growth gets. This is in contrast to waterfall scrubbers, which mostly flow water on the outside of the growth, leaving the inner layers of growth without flow.
    There are a few interesting points to discuss in this above paragraph. Let us start with this one:

    Quote Originally Posted by SantaMonica View Post
    First, the enclosed growth compartment increases the dwell time of the water and bubbles inside the unit so that they rub the algae many times before leaving the compartment. This actually reduces nutrients (nitrate, phosphate) to a level lower than the outside water, which allows greener growth to occur sooner (lower nutrients grows greener algae) inside the unit, especially in high-nutrient aquarium water. In other words, the SURF2 creates a lower-nutrient ecosystem inside itself which is different from the rest of the water in your aquarium.
    I don't know if anyone else caught this, but this basically acknowledges what I have been saying for a while - the Upflow type scrubbers have inherently low-flow, because the action of bubbles rising does not pull water through the unit at a significant rate. Admittedly, the UAS flow rate is nearly impossible to measure, but I think this is something that we can all agree on, specifically, when compared to waterfall scrubbers.

    The "dwell time" concept is not really new, but the SURF seems to make it a priority. I would agree that the water exiting the unit should be very low in nutrients when compared to the rest of the tank water. However this is not a concept or technique that is necessarily limited to the SURF or UAS type scrubbers - not at all. It's not even limited to scrubbers. All one would need to do in order to create a similar low-nutrient ecosystem with any other scrubber (waterfall, dump bucket, you name it, any scrubber) or any other filtration system in general is to put the supply (pump) in the same compartment as the effluent (outflow) and then regulate the rate of influx of "dirty" tank water.

    There is a give and take with the dwell time issue:

    UASs (HOG, SURF, etc) = Smaller amounts of water that is a lot cleaner than the rest of the tank water
    Waterfalls, Horizontals = Larger amounts of water that is just a bit cleaner than the rest of the tank water

    One could recirculate the water from one end of their sump to the other and pass all the water through the entire filtration system repeatedly, and then have a low flow/return from the tank and achieve the same thing. But does this necessarily mean that such a method is more effective at filtration? I would say at best, it is just different - 6 of one, half dozen of the other. Each has their pros and cons, that's all.


    Now to the middle sentence:

    Quote Originally Posted by SantaMonica View Post
    This actually reduces nutrients (nitrate, phosphate) to a level lower than the outside water, which allows greener growth to occur sooner (lower nutrients grows greener algae) inside the unit, especially in high-nutrient aquarium water.
    The reference to greener growth occurring sooner in a low nutrient environment does seem to be true in many cases. When you put a waterfall scrubber on a tank that is in really bad shape, it takes a while to go through the dark growth stages. The point at which the algae really turns green and takes off, to me, is not really established. It's too hard to put a finger on exactly what causes a screen to go green fast. I have had customers put one of my units on their tank and literally get a solid mat of thick emerald green in 10 days. I have had others take months to get anywhere close to green.

    I think it's safe to say that GHA is better at filtering when compared to other forms of algae that might grow in high nutrient water (like brown slime, black slime, yellow, etc). Dr. Adey's research has always claimed that true Turf Algae has a higher rate of uptake (fixation), and (I assume) that's why he chose to build his Algal Turf Scrubber the way he did (admission: I still haven't read Dynamic Aquaria...). The advent of the waterfall scrubber has really amped up the ability to grow GHA faster due to the slot pipe, proximity of light, rate of flow, and uses of more efficient light sources. So it may not actually be that GHA is better at filtering, but rather that our method of cultivation (growth) is just that much more effective. Again, none of this as actually been (recently) studied scientifically and specifically related to how we in the scrubber community implement these methods. Well there was a tangent...back to the point now!

    I think the true test of this idea would be to put a scrubber on a high nutrient tank (any scrubber) and let it grow in a restricted volume environment. In a way, I had planned on doing something like this with my grand experiment plan, which will probably never happen because I don't have the time. But anyone could take their scrubber and make this happen - except those that feed their waterfall scrubber directly from their overflow (must be a pump-fed scrubber)


    Next up:

    Quote Originally Posted by SantaMonica View Post
    Also, the position of the air bubble inlets (below the growth) causes the bubbles to flow through the growth no matter how thick the growth gets.
    Quote Originally Posted by SantaMonica View Post
    ...Rough surfaces are critical for allowing algae to attach and grow and thus provide strong absorption of nutrients...
    ...Previous algae scrubber screens were made from "slippery" plastic canvas that is used for sewing and knitting; algae take a long time to attach to it...
    I'm still not sold on bubbles being the key. My UAS test unit has a bubble bar that clogs up in just a few days, and this forces all the air to come out of a few of the holes. I get just as much growth on the areas of the screen that has zero bubbles "rubbing" on them as I get in areas where all the bubbles go. Even the SURF has GG on the bottom/sides of the box, which are well and far away from direct bubble contact, yet these surfaces grow algae also.

    When I clean out my UAS, I get just as much growth on the submerged acrylic surfaces as I scrape off the screen. I can scrape the screen, put that in a pile, then scrape out the box, and put that in another pile, and they are about equal. All of this algae is very loosely attached - running the screen under tap water release most of it without even touching it. After over a year of growth, I can wipe the screen clean of growth with my fingertips, leaving a screen that is just stained green, with no growth stuck in the holes.

    This is in contrast to my waterfall scrubbers - using the same light and proximity - which need to be scraped, and the algae gets more strongly attached with each cleaning, and the screen holes get filled in with algae that needs to be scrubbed with a stiff brush to be removed (which I don't do).

    In my experience, algae adapts to it's environment. If you put it in an environment without a lot of high-speed laminar flow, such as UAS, it will not need to anchor strongly. If you put it in an environment with high speed laminar flow, such as a waterfall or even some horizontal scrubbers, it will anchor strongly.

    I do agree that rough surfaces, in general, are critical for algae attachment. However, this is more of a long-term issue with UAS based scrubbers. I think the more correct statement is that extremely rough surfaces, like the GG surfaces, are much more critical for UAS type scrubbers, as the algae just doesn't need to attach strongly. The GG surfaces essentially force the algae to attach more strongly.

    What I'm saying is that the plastic canvas is the wrong material for the UAS type scrubbers. We didn't really know it, but it always has been the wrong material, and it likely has been the reason why so many people have had problems with UAS scrubbers not performing well. I think the GG surface is a great thing for the UAS scrubbers, but I really wish, Santa Monica, that you would stop slamming on waterfall scrubbers and plastic canvas.

    References have been made (by Santa Monica) about the plastic canvas having a wax coating for releasing it from the injection mold, and even one post that suggested that the screen was coated in PTFE (Teflon), neither of which is true. I spoke with the manufacturer, and examined screens before and after boiling/rinsing/scrubbing/bleaching, and there was no difference. For some reason, rather that promote the advantages of the GG surfaces for UAS applications, you decided to wage some sort of campaign against plastic canvas in general.

    Plastic canvas is, IMO, an epic failure for use in the UAS. I feel pretty comfortable saying that. I can respect that you don't want to divulge the GG material. It does seem like the perfect material for the UAS scrubbers, which you have applied for the patent on, and worked very hard to develop. I can also understand why you might be reluctant to admit that the plastic canvas was the wrong material (in general) for UAS type applications (even though it does work well for some, just not consistently).

    The plastic canvas is still the perfect material for the waterfall scrubber. Algae can attach to it quickly, if it is properly roughed up, and if the rest of the scrubber is properly built. Speed of attachment and growth depends on many factors, not just the screen material. Algae will anchor to plastic canvas strongly over time, and will fill in the holes, which allows for rapid re-growth. I have never had detachment issues on any of the scrubbers I maintain - even with super-thick 3D growth. The material is very durable, easy to scrape clean, and as long is it is initially roughed up properly, it should really never need to be replaced, unless it gets torn from scraping too hard - I have yet to tear a screen.

    Necessity is the mother of invention. If the Plastic Canvas worked as well as it does in the waterfall scrubbers, you may not have had the need for coming up with the GG material. If your tank had not cracked and forced you to put everything into a tub, you may never have come up with the SURF.

    ...I had to cut this short and attend to business, still have a few more comments to add, eventually...

  2. #2
    Administrator
    Join Date
    Oct 2008
    Location
    Salt Lake City, Utah, USA
    Posts
    10,565
    Even the SURF has GG on the bottom/sides of the box, which are well and far away from direct bubble contact, yet these surfaces grow algae also.
    They do have direct bubble contact: Recirculating, smaller bubbles.

    such as UAS, it will not need to anchor strongly
    Wait till you see a video of the scrubber being lifted out of the water by only the attached growth

  3. #3
    Banned
    Join Date
    Aug 2010
    Location
    USA
    Posts
    2,710
    Quote Originally Posted by SantaMonica View Post
    They do have direct bubble contact: Recirculating, smaller bubbles.
    So does mine then. But the majority of the growth purportedly was supposed to be from direct contact with larger, fast moving bubbles, as was the original theory - "rubbing" causing alternating wet/dry conditions, which I don't buy into. I think it is just about flow and/or randomness. Waterfalls have flow but not a ton of randomness. Horizontal (oscillating/surge type) have randomness but intermittent flow. UASs have randomness and low flow.

    Quote Originally Posted by SantaMonica View Post
    Wait till you see a video of the scrubber being lifted out of the water by only the attached growth
    I believe it! Like I said, the GG and the string/ribbons allow a large, rough area for the algae to anchor onto. A lot of weakly anchored algae can be collectively strong, similar to a bunch of pencils being harder to break than a single one.

    I bet I could lift up my entire full plastic canvas screen of algae by thumb and forefinger from just a few strands. Point being they are individually more strongly anchored to the plastic canvas in a waterfall situation, whereas the same plastic canvas in a UAS would not have strong anchoring, because it is the wrong material for UAS.

    The way I see it, the GG allows for stronger anchoring, which means faster re-growth because the algae is forced to anchor to a larger area, thus is is harder to remove, whereas the plastic canvas could be too easily wiped clean and would not grow back very fast. It is not the fault of the plastic canvas, it is the implementation of it. Users are used to scraping screens and this method of harvest does not directly translate to UAS - you must not clean the screen as vigorously, or you must use a material that cannot be cleaned as easily - such as the GG.

    Without trying it out myself, I would venture to guess that the GG material would actually not be as user friendly in a waterfall setup, if it could even be done. I know that an aragonite screen was tried and it wasn't that great, but it was just one person trying it. No flow through the screen, no light transmission, hard (if not impossible) to scrape, etc. So canvas for waterfalls and GG for UASs.

  4. #4
    Banned
    Join Date
    Apr 2011
    Location
    USA
    Posts
    940
    I really need to get off my butt and make my new ATS. I am thinking of calling it a Pyramid Scrubber. Basically 3 screens in a chamber, 2 almost vertical but with a slight angle so the top of the screens touch but the bottom of the screens touch the bottom corners of the box. On the bottom there will be another screen for the 'uas/floating' scrubber that will be raised off the bottom with some spacers so the water can really mix through the bottom screen. The output will not be on the bottom, but on the sides about 2" up so that the bottom screen is submerged but very turbulent from the water coming down from the top. There will be no slot that the screens go into like is common on water fall scrubbers today, there will be a custom tray that the input water comes into. It will have slots cut on a table saw at angles to guide the water down the screens with a small riser pipe at the end of the tray to act as an emergency overflow in case the tray somehow gets clogged, although in my head I am hoping that isn't even a possibility but it is always good to have fail safes in place.

    As for any lighting concerns, I believe we have figured out what is needed for that and then some. We are now starting to go overboard with lighting so I think the standard R/B LEDs on both sides will still penetrate and grow algae on both sides of the screen and the bottom screen without the need to get crazy with rigging up lights in odd ways to light every surface of the screens directly. It would only be an issue if not maintained/cleaned properly, but that can be said with any piece of equipment. You don't empty/clean a skimmer or change media in reactors, they will also cause issues.

    I honestly think we are dealing with different algaes and/or mutations of algae with our current methods. Reason I think that is the algae on my water falls grows great.... until it hits the water line. The botton 1/2" of screen that is submerged does not grow algae like the rest of the screen, yet, when I (and Garf), put screens under the water fall scrubbers they grow algae just as well as on the water fall screen. I think different algaes or variations will grow better in different types of growth mediums. Combined, it should provide much better filtration than any single type.. or so I hope.

  5. #5

    Join Date
    May 2012
    Location
    usa
    Posts
    27
    i think it not really about what kind of algae or how much growth. its how well do they remove nutrients. particularly phosphates. there were lots of UAS growing algae, but they did not remove phosphates as well as the waterfall. i like the way SM has built his new scrubber it looks so easy to maintain i hope it can perform as well as the waterfall. also i hope it can be replicated without the secret green grabber substrate. i personally can't justify spending that amount of money on it when i can make a waterfall ATS for so little. my personal favorite of all the scrubbers i have seen is "the morgan" ATS.

  6. #6
    Banned
    Join Date
    Aug 2010
    Location
    USA
    Posts
    2,710
    Well I think you can DIY your own Green Grabber. Just use hydraulic cement and aragonite sand. Particularly, Marco Rocks mortar and Caribsea Special Grade Reef Sand.

  7. #7
    Banned
    Join Date
    Apr 2011
    Location
    USA
    Posts
    940
    Am I the only one thinking the 'green grabber' method is taking a step backwards? I see it as a huge negative, not a positive. Reason being is 3 fold, 1, algae is going to grow more dense, leading to quicker die off as it smothers itself, especially on the new floating scrubber that just uses air bubbles to provide flow, 2, it seems like a detritus trap, and 3 it seems harder to clean and if you clean it good you risk removing some of the substrate.

    The water falls are somewhat of a detritus trap as it is, I envision a green grabber type of growth turning to a slimy mush pit fairly quickly. I can easily skip a week of cleaning my water fall and the algae is still strong and lush green, I don't see that really being a possibility with the floating scrubber because I think if you skip a week the water quality may get really bad in the second week as die off occurs and massive amounts of detritus starts to break down. I think the screens we use are great as they provide enough surface area for growth and leave enough open holes to not have the smothering issues I mentioned. The only way I can see the green grabber method working is with massive amounts of flow, something like a strong wave crashing down on it every few seconds to really beat the algae to keep it clean and strong, which seems like way more work to make one function properly vs other methods.

  8. #8

    Join Date
    May 2011
    Location
    UK
    Posts
    15
    I've always struggled with my UAS, whereas my horizontal does much better (designed more for preventing a waterfall between sections, rather than a specific scrubber). Going back to a waterfall scrubber.

    I've noticed (due to lots of hair algae in the tank) that the darkest green, most difficult to pull from the rocks hair algae is in the high flow areas near the MP40Ws I have. The stuff that is really easy to pull off is in the low flow areas and is a much lighter colour. So, I can support the high flow is stronger grip and better growth.

    Additionally, we get hair algae growing everywhere in the tank, not just in the areas exposed to air, so, maybe hair algae would grow in a dedicated tank that just had high chaotic flow, plastic canvas' on the sides and bottom along with lots of light........

  9. #9
    Banned
    Join Date
    Aug 2010
    Location
    USA
    Posts
    2,710
    Ace, I had that thought as well regarding die-off, especially with the video that SM posted of the harvest. But if that was the case, then I would be getting die-off from my inch thick 3D growth on one of my scrubbers, and I don't really, even at the 17 day point.

    Also my point with the GG stuff is that you don't want to clean it, because 1) you need attached growth to stay in place and grow back and 2) you probably can't remove it without scrubbing hard.

    If the GG is Marco mortar (cement) or portland cement or something like it, you're not going to chip it off as long as the hobby box it's bonded to is strong and inflexible, and I imagine rouged up with a rasp prior to adhesion.

  10. #10
    Banned
    Join Date
    Apr 2012
    Location
    Uk! England
    Posts
    1,212
    Personally, I think algae will grow anywhere with little consideration for the material. It's just a function off settlement, flow and horizontal surface area (on initial start up anyway).it seems that after initial settlement has taken place, flow can be increased without problem. Perhaps someone will just get a roughed up screen screen, put it in the sump horizontally with low light and flow, leave it for a week or three, then convert it into a vertical high flow to see if it takes off faster than an initial high flow situation. The only benefit to the GG could be all the crevices it may or may not contain,causing low flow regions, however in the boiling couldron of the UAS these benefits could be counteracted.

+ Reply to Thread
Page 1 of 2 12 LastLast

Thread Information

Users Browsing this Thread

There are currently 1 users browsing this thread. (0 members and 1 guests)

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts