My lighting comments are the same as above. They should be at least 1 watt per square inch, with big reflectors, and within a few inches of the screen.
Now consider this as info for other readers who have not tried a dump bucket...
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Now I come to a site dedicated to scrubbers and I get the same response.
Yes, because you said your phosphate filtering is not strong enough. The above posted reasons are why.
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This is not a static horizontal design and should not be conflated with one.
It's worse (for filtering), as stated before. Surges are great and fun to watch and have, however, and they can be done by themselves.
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the actual question about lighting
Well if the question about lighting it to try to make the design filter better so as to fix your phosphate problem, I think I explained it above; the lighting is not the issue.
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many Algal Turf Algae (ATA) [but not all] have evolved to grow best at and near the oceans water line.
Because, remember, they have evolved in an area with (almost) unlimited surface area. But when you can't grab more surface, the only other way to grow is up.
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the principles that I understand and use are very well documented
Yes, but you are leaving out the principles of self-shading. If algae grows "up", it shades itself. In algal studies, this is called self-shading, and is the mechanism for algal growth exiting the exponential growth phase that we want to stay in.
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They also takes advantage of that zone of high turbulence and high sunlight to out pace predation.
The high-sunlight adaptation, which uses darker growth and works very well for this, is the very mechanism which contributes the most to self-shading.
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A dump bucket allows the algae to stand up and flow with the water in the tray, waving back and forth as it does. Non-constant water direction and velocity insures great contact exposure to the individual strands of algae.
True. At least, when the water is covering the algae. If yours is configured to minimize the dry time, that's good.
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Non-surging laminar flow lays algae strands down like a comb does to your hair.
Very true, especially with waterfalls. When I clean my waterfalls, whenever there is a growth spot over an inch thick, if I don't clean soon enough, I'll get a light-brown wheat underneath where it died. But from what I've seen so far with upflows, it seems to not matt-down as much since it's floating in water.
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Alternating light intensity stimulates photosynthesis, respiration and growth in both. It was found the more intense flashes followed by and equal amounts of relatively lower light is more effective than a contain amount of light.
It probably is, for certain mechanism. Periphyton in tree-covered streams, for example, make most of their growth during the milliseconds of flashes that come through the leaves. However, remember how photosynthesis works: One unit of light (say, 1 second) + one unit of nutrients = one unit of growth. If you take that one unit of light (1-second) and break it up into flashes, the integration of those flashes over the 1-second will be less total light than the fully-on 1-second. So if the light source itself remains the same, and only "flashing" is added to modulate it, then the total available filtration will be less because the summation of light is less. Although some bio mechanism may indeed be stimulated by the flashes.
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The prismatic spectral shift of waves gives more variety of the light’s K value as well. Being able to eat steak all the time is good but you do need to eat your vegetables as well.
This is true. If an algal species is looking for shifting K values, this would supply it. The bubbles in an upflow might too, if the light source were a CFL (and not a 660 led).
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Algae that can stand up for part of the time, not touching its neighbors just performs better. Much like a kelp forest, water flow is optimized if stocks or strands don’t touch all the time. In a 3 inch deep agitated tray with water surging, light reaches and permeates all of the algae, right down to and through the roots.
I have to differ on this. If dark or black turf is more than 1/4 inch thick, and you can't see the white screen that's under it, I don't think any light is going to be getting through it. Plus, when I clean even 1/8 inch thick dark growth, I find dead areas under it much sooner than under the green areas that are much thicker. Lastly, and probably most important if filtering is the goal, is that I've seen over and over (with my tank and with others) how filtering reaches a maximum when the scrubber is growing thick GHA.
Of course, you should make what you like to make. The surge is fun to look at, and I'm sure it helps many corals, and tangs sure do love it too. But if the goal is phosphate reduction, I can't recommend combing the surge with the scrubber no matter what lighting is used. Maybe a separate surge and vertical scrubber would really be easier to build overall. It sure would (my opinion) filter much better given the same size, wattage, and cleaning schedule.