Algae Scrubber Advanced

[Mike Edwards123]

Not sure if this is the best place to post this but I am in the beginning stages of resurrecting my Eco Wheel algae turf scrubber. Been sitting dry for 12 years or so after a move but time to restart. This is a algae turf scrubber on a wheel powered by a air pump. Think of the wheel as a 2 foot diameter and 2 foot wide paddle wheel. Algae screen is attached to outside circumference of the wheel that is spun around by the water/air circulation. The light was a panel of cfl light which was 2ft by 2 ft that sat on top of the wheel. I am looking to see what would be the best led replacement. Lots of info here that I will need to read but looks as if a red and blue mix is the latest trend

[Floyd R Turbo]

My rule of thumb that I have followed and recommended has been 660nm Deep Reds and 440-445nm Royal Blues. For the DRs, quality does matter so don't go cheap. I get Philips Luxeon ES from Steve's, he gets a specific bin that seems to work well.

I also get teh blues from Steves, but you might also consider using the True Violet he offers. Very much recently, one user replaced his blues with the deep violets and got great results.

As far as a ratio goes, I've stuck with two blues running at 350ma for every 6 deep reds running at 700ma and that seems to do well, but even that might be too much blue. So you really don't need a lot of blue.

[Da Maui life]

Floyd, What would you run the true violet at, and how many? Same as the blues.

[Floyd R Turbo]

I can't say with any certainty based on my own experience, but based on what others have told me they run them at 700mA along with the rest of the deep reds. I would suspect that this would be OK to do. I compare 445 RBs & 420 Violets to 630 reds & 660 deep reds.

The 630s and 445s will be of higher intensity, at least to our eyes. I know that based on my conversations with people in the hydroponics grow-light industry, that 630s have roughly 3x the intensity over 660s (at least, for what the plants "care about"). However it seems that this is way too much intensity for algae scrubbers. My experience with running 445s at 700mA vs 350mA showed me that 700mA RBs would easily cause photosaturation, but this was not the case with the 660s at 700mA.

Since a deep violet is on the other side of the blue spectrum, it would make sense that you would be able to run them at 700mA, the same as you can run a 660 at 700mA and not cause saturation (at least not in the majority of cases).

In fact, one person who tried this was running 700mA on 4-660s and 3-420s on each side of a screen that is about 6" x 6", roughly. But, he was also running 3 royal blues at full power on the same screen, so maybe that is not a very good assumption to make.

For now I would stick to a 6:1 DR:violet ratio, if running full power. If running a 2-sided screen, I would recommend offsetting the violets such that they are not directly across from each other.

When I get a chance, I'm going to modify my personal unit such that it runs 2 violets per side, but in parallel such that they run 350mA (current divider). I also have another unit running on another tank with 2 arrays of 6 deep reds and one full-current royal blue in the center, I will swap those out for violets as well and then I'll have 2 different scrubbers to monitor

[Da Maui life]

I’m currently looking at building a one ‘cube’ scrubber 'like' the L2. Thanks for answering my questions.

[SantaMonica]

Wow an algae wheel. Have not looked at those in years.

[Mike Edwards123]

Yeah. It's by a company that is no longer in business. Aquatic Engineers. May not be as small as today's waterfall ats but the tank runs on only an air pump and lights. No impellers. It creates a surge as well although not enough of one. I am also converting my 90 gal reef tank to a 125gal and will be setting up a waterfall ats on that.

[Brummie]

I've re-visited the Adey 3D screen theory. My conclusion is that if you have a submerged screen then the algae acts as substrate for diatom growth (and other epiphytic algae), increasing biomass. Now I look back at the article in question, Adey did elude to this. So here's a pic (changed lighting also to a blue spectrum, to simulate 5 metre water depth).

[Brummie]

Originally Posted by Floyd R Turbo

I should measure my scrubber lights with a PAR meter one of these days, our local club has a $375 apogee meter that anyone can use.

I used one once when I compared an e-shine 50W bar to a Nova Extreme T5HO 2-lamp fixtures with 2x 2700K lamps in it. The peak in the middle of the LED fixture was way higher, but the coverage was not as even. with the LED (tighter distribution)

I know I've only used a cheap ipad app but I've measured the light intensity of an LED growlight 36w (3watt diodes) at a distance of two inches from the light source and it peaks at 1600 ft candles. Now, considering over 1200ft candles appear to be detrimental even dangerous to growth should we at least agree a maximum of 1200ft candles. This reading is without lenses.

Edit - Hmmm - now I've checked a CFL 23watt (with diy reflector) and it's upto 1800ft candles at 2 inch, needs to be 4 inches to get to below 1200ft candles.

[Floyd R Turbo]

I'm not sure if foot-candles is what you want to measure. You want to measure radiant flux, as this does not depend on human perception.

[Brummie]

Originally Posted by Floyd R Turbo

I'm not sure if foot-candles is what you want to measure. You want to measure radiant flux, as this does not depend on human perception.

I'm probably comparing apples with pears anyway. Quite how LEDS relate to white light output is beyond me, although my initial thoughts would be that LED power output should be considerably less than that experimentally shown to be inhibitive to growth in white light as nearly all the LED output can be utilized but only a fraction of white light is available to chl a, b. There are the accessory pigments to consider in white light though, along with cryptochromes, neochromes and phytochromes.

[Pny]

Originally Posted by Floyd R Turbo

I know that based on my conversations with people in the hydroponics grow-light industry, that 630s have roughly 3x the intensity over 660s (at least, for what the plants "care about").

I guess the hydroponics guys are growing plants and not algae? Not sure if their knowledge is applicable here... Its obvious that they talk about absorption of chlorophyll b, since chlorophyll a has its absorptions peak at 665 nm. Do we know if the algae we grow in the scrubbers use chlorophyll a or b, or both?

[Floyd R Turbo]

I was told that 630s would be better because they output about 3x the intensity of 660s, and for plant growth they were by far the better way to go when looking at output radiant power per unit of input watt.

But so far in the real world, this does not hold true for algae. I believe this is both due to intensity and spectrum.

From my studies, I found that the chlorophyll A spectrum is used during times of intense sunlight, and the chlorophyll B spectrum is used during cloudy times, sunset, sunrise, etc. So B is sort of a 'backup' when A isn't available. I can't recall where I read that though.

[Brummie]

I'm still very fuzzy about the advantages of red over blue. From stuff I've read, too much red just turns the light into heat and also causes more chlorophyll production which in turn causes more heat production instead of growth.

[salty joe]

Little bits and pieces I've picked up from you guys makes me wonder if blue has not been a winner because it's been too intense.
Based on the wavelengths plants utilize, I have a real hard time believing blue would not grow algae quite well. Especially since blue is generally considered for vegetative growth and red for flowering.

[Brummie]

Using this spectrum, here's my first full 7 days, day zero first (harvest time);

[salty joe]

How does that growth compare to growth from all red?

Is that a metal halide? I wonder how all 430 (or whatever blue wavelength is best) LED would do?

[Brummie]

Originally Posted by salty joe

How does that growth compare to growth from all red?

Is that a metal halide? I wonder how all 430 (or whatever blue wavelength is best) LED would do?

Wasn't all red before, it was a cheap red/blue led combo. The new pics are MH, yes. Although MH are less efficient I'm just testing the light, with a view to broad spectrum LEDS and not just red or red/blue combos. So far, I see more epiphytic diatom growth at day 7 but overall growth is similar to high red to blue ratios.

[Brummie]

I've been doing a bit of digging around on light intensity;

http://reefcentral.com/forums/showthread.php?t=2424221

If anyone has pertinent info then please add.

[Brummie]

Seems as though the inverse square law of light does not apply to scrubbers.

[Floyd R Turbo]

Looks like we're on the way to a better way of looking at lighting and scrubbers

[herring_fish]

Here's a quote from ADEY

Right, the bit I'm struggling to believe. I've measured LUX at my screen surface at 6600 LUX. So using the conversion factor this equates to just 93 uE. If this is correct, and ADEYs quote is accurate (no reason to believe why not) then I could safely increase lighting by 12 times if that's at all possible?

I’m a design engineer so I should know math and stuff but this makes my head hurt.

Seriously, I went to review my old calculations and ran across this somewhat dated chart from Dr. Adey’s book. The red lines and conversion was just there for my particular tank. Please ignore them. His chart was what he actually used in his setups. The lights appeared to be a few inches away from the screens, 3 or better.




One thing to note is that his studied assumed the scrubber was a 3-D scrubber with wave turbulence which is, according to his studies, 50% more efficient than those that do not have this type of design.

These designs allow for better respiration along with mineral and nutrient uptake over a longer time period. As harvest period approaches, in other designs, his observations might change quite a bit.

Die off might start earlier if metabolism is revved up that much. As flow to the individual strands begin to decay, respiratory distress might start earlier and be worse than normal. This could affect your average net uptake.

What I’m thinking is that if you use those higher light levels, you might need to be sure that you clean the screen promptly on schedule.

[Brummie]

Originally Posted by herring_fish

I’m a design engineer so I should know math and stuff but this makes my head hurt.



Seriously, I went to review my old calculations and ran across this somewhat dated chart from Dr. Adey’s book. The red lines and conversion was just there for my particular tank. Please ignore them. His chart was what he actually used in his setups. The lights appeared to be a few inches away from the screens, 3 or better.









One thing to note is that his studied assumed the scrubber was a 3-D scrubber with wave turbulence which is, according to his studies, 50% more efficient than those that do not have this type of design.



These designs allow for better respiration along with mineral and nutrient uptake over a longer time period. As harvest period approaches, in other designs, his observations might change quite a bit.



Die off might start earlier if metabolism is revved up that much. As flow to the individual strands begin to decay, respiratory distress might start earlier and be worse than normal. This could affect your average net uptake.



What I’m thinking is that if you use those higher light levels, you might need to be sure that you clean the screen promptly on schedule.

I agree. When the filamentous stuff is present, the algae acts as the 3D substrate. On Adeys manufactured 3D screens he merely tried to emulate the algal mats where they were absent in Dino dominated systems. Lights been increased for a couple of days now and it certainly seems to have filled out (15 days in total)

[Brummie]

Right, so Adey used 1600 MH watts over 2 m of screen. Hmmm. I think I've worked out that on my size screen (13x10 inch) he would have used 67 watts., mine is 150w.

[Brummie]

This lot used 400w MHs x 2 and got readings double the readings I got (on a large screen) so I'm quite content that the calculations I've made are vaguely correct.

Page 77, 78 (actual page numbers)

http://drum.lib.umd.edu/bitstream/19...117E_11236.pdf