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Thread: Scrubbers compared to refugiums

  1. #21
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    Quote Originally Posted by ferdinand View Post
    yeah, i don't know your setups, even when you put a picture or video, i'm still not 100% sure it's yours too though.
    My flickr album.. my youtube channel.. still don't think that is my tank?

    Quote Originally Posted by xerophyte_nyc View Post
    Actually, it is true. Take a closer look at trees and really any branching plant. The newer and also more active leaves are at the tips of branches. When growth is fast, the older leaves become senescent at a quicker rate. Inhibitory hormones at the meristems prevent side shoot development to enhance photosynthetic surface area.
    Ok, I am taking a closer look at this 'branching plant' I found on google images, I don't see leaves dying below the top of the plant. It looks pretty uniform to me actually.


  2. #22
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    You have great growth going there!!!
    150G. Reef/Mix
    125G. 3 Regular Oscars/1 Jack Dempsey
    75G. 20+ Africans
    40G. Fish/Reef. Algae Scrubbers on ALL my SW
    10G. SW Fish/Reef.
    10G. SW Hospital/new fish quarantine/pod breeder tank
    6 stage RO/DI system 200 GPD.

  3. #23

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    a good amount of money in there lol

  4. #24
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    "Found on Google Images" - yeah, right. Thanks for sharing Ace.

  5. #25

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    Plants position their leaves to use sunlight as efficiently as possible.

    I will admit the stuff in the image above left me a bit hazy though.

  6. #26

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    Wouldn't mind some of that action right about now, LOL!

    Just walk through any forest or area of mature growth and you will see that the older branches and lower parts of plant life have leaves of a different morphology. It's not even debatable. Speak to any horticulturalist/ botanist/ ecologist if you want more details about this.

    Are there examples that show otherwise? Sure. Your photo shows a plant that was likely grown indoors where the lighting regime can be modified to attain better growth. But even if that were not the case, there are plenty of fast growing plants that can grow so quick that many leaves remain on the plant. In due time, even they will have older, yellowing leaves.

    Back to algae: if light is intense enough, or if the algae is illuminated from wide angles, then you can certainly get good growth where the net result could be adequate. However, it is difficult, as far as I'm concerned, to argue that photosynthesis occurs at the same rate when chlorophyll is clearly shaded by other growth.

  7. #27

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    Many leaves on that plant will die of light starvation and require pruning to avoid air stagnation and powdery mildew, and I am sure it has seen pruning already. Looks a little stretchy but I am sure that will go away after it goes into flowering. Keep doing what you are doing and maybe FIM the tops a little more if you have time... Oh wait, wrong forum.

  8. #28
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    LOL, seriously, not my plant.. haven't grown anything of that nature in decades.

    Bottom line, plants differ, some plants do as xerophyte_nyc stated and lose their lower leaves/branches, while other plants do not. Ever seen a Christmas tree? Even the plant above, while yes, the lower leaves will slowly die off before the top leaves, that doesn't mean the bottom leaves are not useful (as I found out the hard way once but trimming the lower dying leaves off, only to cause the plant to hermi from the stress). The dying leaves, while they may not do much in the way of photosynthesis towards end of life, they do act as sort of a battery to the plant. The upper leaves do the photosynthesis and the extra energy from that can be stored into the lower leaves. If you trim off the lower leaves before they are completely dead, you trim off the excess storage capacity of the plant.... but again, different plants behave differently and human interaction can change the growth style drastically (ie. Screen of Green). Waaaaay off topic now though.

    Back on topic.. I still think a scrubber = refugium in many aspects, but obviously not all. A refugium with macro algae can be just as good as a scrubber if built correctly, but I think a refugium will always take more space to accomplish the same goal in regards to using algae to filter the water.

  9. #29
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    Update:

    Scrubbers compared to refugiums

    If you are starting a new tank, then the obvious difference is that a scrubber gives you the option of not having a fuge at all because the scrubber can go on top of, in, or behind the display. There are other uses for a sump/fuge of course, but we'll only cover the filtration concerns.

    A not-so-obvious difference is that a scrubber, if run together with a fuge with macros, will kill the macros even though the macros are much larger. This is because the scrubber thinks the macros are nuisance algae. Some people do run both together without killing the macros, but this is just because their scrubber is not strong enough, and actually the macros might even be slowing down the scrubber because the scrubber thinks it has to remove the macros, and the nutrients in the water, and the nuisance algae in the display. However, if it works for their current setup, good.

    But assuming you have to decide on either a sump/fuge or a scrubber (not both)...

    o Filtration with algae is proportional photosynthesis, which is proportional to Light X Flow X Attachment. Meaning, stronger light grows more algae; stronger water flow grows more algae; and stronger attachment lets more algae grow without it floating away. A scrubber is designed to maximize Light, Flow, and Attachment.

    o The main problem with macros in a refugium is the self-shading that the macros do. Any part of the macro which is not directly in front of the light at any moment is not filtering. And any macro inside of a "ball" of macro (like chaeto) is self-shaded all the time. Only the surface macro that is directly in front of the light is doing any real filtering. A scrubber is designed to have all the algae in front of the light at all times. Rotating the macro does not solve the problem because the time that the macro is rotated away from the light is time that the macro is not filtering. This is why it takes a much larger size of chaeto to do the same filtering as a scrubber.

    o Self-flow-blocking is another problem of macros in a refugium, for the same reason as light-blocking. And the thicker the "ball" of macro, the worse the flow-blocking.

    o Particle trapping is another result of a ball of macro. These particles need to cycle back around to feed the corals, but instead they get trapped in the macro and rot, and in doing so they block even more flow and light.

    o With a scrubber, there is very little water standing in the way of the light. Also, the light is (or should be) very close to the scrubber... 4 inches (10cm) or less. The power of light varies with the inverse square of the distance, so going from 8" to 4" actually gives you 4X the power, not 2X. And the nutrient removal power of algae is proportional to the power of the light, because it's the photosynthesis that is doing the filtering.

    o Rapid flow across the algae in a scrubber gives more delivery of nutrients, compared to the slow moving water in a fuge. Filtering is proportion to nutrient flow.

    o The turbulence of water moving over the sections of algae in a scrubber help to remove the boundary layer of water around the algae. This boundary layer slows the transfer of metabolites in and out of the algae. There is no turbulence in a fuge (if there were, you'd have waves and bubbles).

    o Scrubbers do not let food particles settle like a refugium does; most particles flow right out of the scrubber.

    o Scrubbers do not (if cleaned properly) release strands into display, like chaeto does.

    o Scrubbers do not go sexual, like caulerpa can.

    o Scrubbers do grow lots of pods; more than was previously thought.

    o Scrubber don't, obviously, provide a place for snails and crabs, etc.

    However, if you already have a sump with an empty compartment, and you don't mind using all of it and putting a light over it, then maybe it's easier and cheaper to try macros than even a DIY scrubber.

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