Algae Scrubber Basics

[Floyd R Turbo]

I'm pretty sure that somewhere along the line, someone said that GHA is specifically not "turf" algae...you're saying that in the broad sense of that category, it is - correct? Maybe I misinterpreted what I read and it was more of a method of differentiating growth types in layman's terms. "True turf" vs "GHA"...still turf, just doesn't look quite the same

 

[herring_fish]

Yes As defined by the coiner of the phrase (Dr. Adey) , turf is a bigger category that includes GHA and bigger stuff at well. Dump bucket can grow the fast stuff but is not limited to it.

 

[Mock]

Recently I removed all the sand and rock from my refugium because it was just so laden with detritus it was becoming a very bad nitrate trap. I we at it and removed the sand bed that was in it, rinsed all the rock really well and placed them into milk crates and when it was all said and done my 75 was all clean with well packed rock in easy to remove baskets.

I was looking at ways to still grow micro algae when I remembered what I had read on algae scrubber and wondered if this was something I might be able to put into place with what I am working with now.




As you can see in the photo I linked I am thinking of running this a little less than normal. I have a 75 that drains into one end and the water basically runs to the other before dumping into the rest of my sump set up.

I was wondering if this might work, I am thinking about building a floating scrubber to place that simply floats on the water surface of the 75 with screens in the top of it. The water would pass across it and allow for algae to grow on this mat.

I was wondering if anyone has ever done this before or have seen anything like it done. I can bring my light down lower if needed and pretty much have everything it would take but the real question was the flow, I know over time as the closer end grows the other end may not get adequate flow so, I was just turning to you guys to see if it would be a viable design.

 

[kegogut]

So its been 13 days since my last cleaning and since then I've added two more 23w CFLs which has turned my algae greener in color.

This is what the screen looked like before cleaning.


And here is what was harvested.

Its definitely more than I got last time,but I also waited for 13 days instead of 7.

This is what the screen looked like after cleaning.


Im gonna wait 14 days or so to see how the growth is with the 4 CFLs and a bit more flow

 

[dn100]

Floyd thanks for the useful reply

Has anyone experienced Cyanobacteria or dinoflagellates disappear from the main aquarium soon after starting an algae scrubber?

What colour does the algae change when nitrates and phosphates drop to low levels ? When the desired nutrient levels are reached, does one simply decrease the photoperiod ? ( apologies if this was answered already)

Thanks in advance

 

[Floyd R Turbo]

Has anyone experienced Cyanobacteria or dinoflagellates disappear from the main aquarium soon after starting an algae scrubber?

Cyano is usually the last to go, but with a well built scrubber it will eventually out-compete it. You may have to use more than one method of nutrient reduction, like carbon, gfo, skimmer, etc if it is really bad.

Dinos - these will typically go away also but my experience is that they show up as a result of you making a change to the system that upsets the balance of bacterial populations. Such as moving a bunch of rock around, changing flow patterns, changing lighting, etc. Usually about 6 weeks after making such changes, you get an outbreak that lasts about 2-3 weeks. During that time, you try everything you read to get rid of it, and it seems to work in about 2-3 weeks. In essence it goes away on it's own, as long as you don't freak out and start scrubbing rocks with a brush and start changing more things - just suck as much as you can out once or twice daily with an airline hose, and only feed a minimal amount every other day about 15 minutes before the lights go out. At least that is what has worked for me.

What colour does the algae change when nitrates and phosphates drop to low levels ?

The algae will generally get a brighter shade of green with lower nutrients. Sometimes thicker growth also.

When the desired nutrient levels are reached, does one simply decrease the photoperiod ?

That is one way you can do it, but reallly what you do it watch the growth and if it starts to turn from GHA to a more yellow and spongey gooey growth, then you have too much light and not enough nutrients.

 

[hawkinmd]

How much of a difference will the wavelength from 660nm to 640nm make? I'm sure this was covered before but have not had the time to read through totally. Any help would be greatly appreciated.

Bill

 

[Floyd R Turbo]

630 is the typical "red" and 660 is the typical "deep red"

630 is actually much more intense than 660. In my discussions with the plant-growth hydro guys, they told me that 630 outperforms 660 when growing plants, tree seedlings, etc by a long shot (3:1 or something like that) but when it comes to algae it does not appear that this translates. The issue might be the intensity. From what I've seen from hundreds of examples, getting even coverage is very key and LEDs do not do this well from a point source unless it is far away, one example being the multichip, which has to be further away to prevent photosaturation directly in front of the fixture, resulting in a 'sweet spot' where it works best, but too close and you get zero growth (or brown slime)

I would imagine that a 630 multichip would be even worse, unless you can dim it way down and get into the 'zone' where the intensity is just right. Historically though, anyone who has made a 630 fixture and then switched to a 660 fixture has concluded that the 660 fixture is much more effective. The kicker though is that they may not have considered the intensity factor, meaning, they were running both colors at the same current resulting in the 630 array being 3x as intense as the 660 array. We didn't really know this had such a dramatic effect until recently when it became clear that LEDs could output intensity levels that CFLs or T5HOs couldn't even get close to, resulting in screen that literally would not grow at all because the light was so intense.

All that being said, 660nm deep red is within the chlorophyll A band, and this is the primary red band that most plant life uses (high noon sunshine). The chlorophyll B band is more of a secondary band, which penetrates a bit more and is kind of like a backup for sunrise, sunset, and cloudy days where the A band is not as intense. At least that's how I recall it being described somewhere I read on the interwebz

 

[kegogut]

BTW I figured I would mention that Lowe's had some releasable zip ties which come in handy when cleaning the screen.

 

[Floyd R Turbo]

Try finding "beaded cable ties". They are the second best thing you can use.

IMO the best thing is the rotatable ring. Just find a slip x slip connector for your size pipe, cut off a ring, clip about a little less than 1/4 of the ring off with a wire cutters, use a file to round off the cut edges and some 150 grit sandpaper to smooth it out, then snap over your slot pipe and cut a hole in the mesh to line up with it.

 

[kegogut]

Try finding "beaded cable ties". They are the second best thing you can use.

IMO the best thing is the rotatable ring. Just find a slip x slip connector for your size pipe, cut off a ring, clip about a little less than 1/4 of the ring off with a wire cutters, use a file to round off the cut edges and some 150 grit sandpaper to smooth it out, then snap over your slot pipe and cut a hole in the mesh to line up with it.

I'm actually using some of the beaded cable ties on my filter sock. I couldnt find those at my Lowes but found the releasable ones and so far theyre working great.

 

[Chris Abbott]

Are the Numbers still coming down for you Dave?

 

[kegogut]

Are the Numbers still coming down for you Dave?

They actually just started coming down. When I started the scrubber they were running about 35. In the month Ive been running it theyve come down to 20 according to API test ( I ran out of Salifert).

Im going to let it run for a few weeks before I clean it again to see how much green growth I get now that I'm running four CFLs instead of two.

 

[Chris155hp]

hey guys! I need some help with my scrubber design and in an effort not to hijack thread ill link my newly started thread http://www.reefcentral.com/forums/showthread.php?t=2485780

 

[widmer]

Floyd, great to see you're still active here, as I have been largely off of the forums for the past couple years. I went through a few pages of this thread, specifically searching for some sort of mantra regarding LED light requirement per square inch of screen. I'm setting up a new tank, it is a 30 gallon tank with a sump in the stand, and would like to use an ATS as my primary (only?) means of nutrient export.

Based on the dimensions I have to work with, my screen will be vertical, 7" wide x approx 10" tall, and one-sided, with approx 35 gph/inch as required. I want to use LEDs as the light source, and based on my sump area, they will be placed exactly 5" away from the screen. So on to my question: What is the ideal mix of wavelengths and intensity for this 7" x 10" x one-sided screen? I have tons of late-model 660nm, 420nm, white, etc LEDs laying around from RapidLED and other vendors, and would be happy to pick up whatever is ideal if I don't already have it.

 

[Floyd R Turbo]

Welcome back widmer!!

My formula is based on coverage, with LEDs about 2" from the screen:

High intensity: one 660nm DR @700mA on each side of every 4 sq in of screen

Low intensity: one 660nm DR @700mA on each side of every 8 sq in of screen, OR every 4 sq in but running at 350mA

For 5" from the screen, I would go with high intensity as you will lose a bit due to the extra distance. So 7x10=70/4=about 18 DRs.

If you want to supplement with anything, I would use either royal blues or hyper violets and run them at 350mA. However, with the 5" distance you might be able to get away with running them at 700mA in the normal series with the DRs, at 2-3" they are too intense and cause photosaturation (zero growth). Use one RB or HV for every 6 or 8 blues, in your case, I would just use 2 of them, but you could use 3 if that makes the array more symmetrical, it depends on how you lay them out

 

[widmer]

Edit: Thanks for the quick reply! I will proceed accordingly. Followup question: I can't help but wonder if by only providing two wavelengths of light (ie 660 and 420), the algae is missing out on various other wavelengths that it might not use so much for photosynthesis, but might be really helpful as a cue/trigger for various metabolic pathways. So part of me wanted to go with primarily 660s, but also add a couple whites in case the additional spectrums might be of any service. Do you have any thoughts on this?

And for my second question: It appears that the roughed-up plastic canvas is still the standard go-to for ATS units. However, I like the idea of something rigid for ease of removing and scraping. I was planning to make my screen out of a ceramic tile that I would coat with a light layer of cement/crushed coral mix, for lots of turbulence. Over the past couple years that I've been away, has anyone had any reported successes/failures with these other screen materials?

 

[Floyd R Turbo]

Santa Monica's UAS designs use crushed quartz, just like pool filter sand except larger granules. aragonite might be good, special grade reef sand comes to mind. This is the go-to type of material for UAS, but that's mainly because the plastic canvas works horribly underwater.

The PC is IMO still the best for waterfall. I remember a tile one a while back, worked OK but the problem with any non-porous substrate used for a waterfall is that growth tends to push the water flow away from the base, so it dies faster, and that combined with a single sided setup where it gets no light from the other side, this is even worse. So I would advise against that.

But if you are going to do it as you describe, make it a slanted screen, 10 degree or so. This will at least keep the base hydrated. The LEDs will penetrate well so this will help with die-off also.

With all of the double-sided LED units I run, I have rarely seen die-off at the base. LEDs really penetrate well.

Also one additional thought on the array - initially, with a new screen, it's easy to over-light (photosaturate) with LEDs. So you can start at a lower intensity until you get a base of growth, then increase it. With your 5" distance however I don't think you'll need to do this, but watch for it.

 

[SantaMonica]

For these types of designs to do much filtering, they need to be right at the surface, with lots of wave action. In other words, lots of air/water interface turbulence.

The pic however looks like the screen is under the surface; this will not work well at all. Best would be to dump the overflow on it.

 

[SantaMonica]

Here is a compilation of dark, slime, and black growths: