Algae Scrubber Basics

[SkyReef]

Sky: What camera do you use:

Hi, SantaMonica. Thanks for your question. I use the camera on my Droid Razr Max smartphone, 8 megpixel. Do you have concerns with the photo quality not correctly displaying what it depicts, based on the photos I posted of my ATS?

 

[Floyd R Turbo]

As for flow I don't think it has anything to do with tank volume. All the screen knows is what growing conditions it has in front of it, and it does not care what occurs elsewhere. If stronger flow helps it's because its delivering more nutrients in relation to illumination and the ability of growth to stay attached.

I absolutely believe it does matter. Take this example.

Tank volume, 120 gallons

Previous scrubber, 20" long x 7 " tall. Flow 20x35=700 GPH. 700/120 = 5.8 tank turns/hour.

Current scrubber: 6" long x 4" tall. Flow 6x35=210 GPH. 210/120 = 1.75 tank turn/hour.

That is less than 1/3 of the overall flow rate. The result is that before, there was zero algae in the display. Currently, there are some clumps and pockets of algae growth. Not enough to cause any kind of issues, but it is a noticeable change. The majority of the algae is growing near the surface, on the loc-line plenum, not on the rocks. There is cyano present on some rocks and in some areas of the sand bed, where before there was not.

Feeding stayed the same (type and quantity), as did lighting. N=0 and P=0.02 which is actually lower than it was with the larger scrubber.

I have queried many users and found that situations are similar when the scrubber is sized appropriately for feeding on a large volume tank.

The conclusion I have come to is that there is an upper limit to the feeding based guideline. So if you feed 2 cubes/day, and you have a 4x6 screen, this will do you well as stand-alone filtration for a tank up to about 100 gallons, more if you have a skimmer running as well (120, maybe 150). After that, you need to increase the size of the screen (and flow/lighting, etc) regardless of what you feed in order to keep algae at bay.

Go the the extreme. 2 cubes/day feeding. 40 gallon vs 400 gallon. 200GPH scrubber flow. On the 40g, 5x turnover. on the 400, 0.5x turnover.

Now granted this is simplifying things, because the full tank volume isn't going in and out, there is mixing, etc etc. But the point is that algae is opportunistic, and if the environment allows it, it will grow. The point of the algae scrubber is to take away that environment. IMO there is a fine line where nutrients, regardless of how low they are kept over a long term basis, remain in the water column long enough on a consistent enough basis that algae can survive in the display tank.

The reduction in the screen size, while it does make sense, IMO has presented unintended consequences. They are easy enough to remedy, i.e. make the screen a little bigger.

There may be other factors at work as well, I will admit that - I can't account for everything. But that's what research is for. Still waiting for that grant so I can quit my job and study this stuff full time.

 

[igadget56]

JohnnyB in SD

Could you please explain these in a little more detail?

1. spaced approx 2.25" on center

2. you might consider designing something with 1.5 or 2x the emitter density.

May be a pic? Thanks Dave.

 

[_shorty_]

Shorty: Increasing the LED power even more will photoinhibit the growth on the glass.

I actually did increase my lighting during this. I started with 15 x 1W LEDs on a 6x9 ish" screen (right on the outside of the glass) - and then increased to 30 x 1W LEDs on the same area. I believe giving better growth, but also making glass growth worse. I used CFL on the other side with the same issue.

What would you recommend?

 

[acroman]

However, if you are wanting to run heavy SPS, the word I have been hearing from scrubber users is that scrubber-only systems tend to lead to lack of PE (polyp extension) and browning of corals as the zooxanthellae appear to be overfed. So adding a small amount of carbon, or a skimmer and carbon, seems to make the PE return.

What interests me the most is why the PE declines. Theories abound. One of them is that since scrubbers do not remove food, the coral is fed well and the polyps don't need to extend. Increasing the light may cause better uptake and thus the need for more food? Dunno...thinking aloud.

Lack of carbon availability due to all the CO2 being removed by the scrubber? The addition of a skimmer would help gas transfer, and *may* be what is fixing the problem.

 

[acroman]

I absolutely believe it does matter. Take this example.

Rate of exit of contaminant = Rate of drained solution x (Amount of contaminant / Volume of tank )

So yes, it absolutely does matter.

Basically this means that the nutrient export capacity is a function of flowrate, AND nutrient concentration, AND tank volume.

Feeding 1 cube a day to a 30L tank and a 300L tank will have the same total nutrient input by mass, but the concentration in ppm will only be 1/10th in the 300L tank.

 

[Floyd R Turbo]

Shorty: Increasing the LED power even more will photoinhibit the growth on the glass.

I actually did increase my lighting during this. I started with 15 x 1W LEDs on a 6x9 ish" screen (right on the outside of the glass) - and then increased to 30 x 1W LEDs on the same area. I believe giving better growth, but also making glass growth worse. I used CFL on the other side with the same issue.

What would you recommend?

My UAS tester box (sits on top of tank) always has a coating of algae throughout the entire interior of the box after 10-12 days. It is so thick that the only areas that do no have any algae are directly in front of the LEDs. This does not seem to affect growth, however. But I do have 6x 660nm at 2" on center, so there is likely still plenty of light getting through.

Lack of carbon availability due to all the CO2 being removed by the scrubber? The addition of a skimmer would help gas transfer, and *may* be what is fixing the problem.

This is also very likely. If I could redact that post of mine, I would. Concluding that PE is lacking because the corals are overfed is a leap. There are way too many reasons for PE or lack thereof, and me posting that was repeating what others had observed, and in short, to say it is so pretty much made me sound like an idiot. But sometimes you have to say stupid things in order to learn.

Rate of exit of contaminant = Rate of drained solution x (Amount of contaminant / Volume of tank )

So yes, it absolutely does matter.

Basically this means that the nutrient export capacity is a function of flowrate, AND nutrient concentration, AND tank volume.

Feeding 1 cube a day to a 30L tank and a 300L tank will have the same total nutrient input by mass, but the concentration in ppm will only be 1/10th in the 300L tank.

Good example as well. Just playing devil's advocate, the higher concentration would take longer to reduce, but would (theoretically) happen faster with a higher turnover rate, and less dilution overall. The lower concentration would take longer to remove at the same flow rate, and the dilution would be greater. I'm envisioning a graph with Y=concentration and X=time, Y would approach zero as X goes to infinity. In the 30 tank this would drop much quicker than the 300, but over the long term, they would look much the same, except for the occasional spike from feeding or snails/fish dying and muddying up the water, etc. But a larger (wider) scrubber or a higher flow scrubber in general would (should) fix this issue.

 

[acroman]

This is also very likely. If I could redact that post of mine, I would. Concluding that PE is lacking because the corals are overfed is a leap.

"Leaps" are how some of the best studies are started

Anyone have access to DO/CO2 monitoring? COD/TOC would also be helpful to test for carbon availability.

Good example as well. Just playing devil's advocate, the higher concentration would take longer to reduce, but would (theoretically) happen faster with a higher turnover rate, and less dilution overall. The lower concentration would take longer to remove at the same flow rate, and the dilution would be greater. I'm envisioning a graph with Y=concentration and X=time, Y would approach zero as X goes to infinity. In the 30 tank this would drop much quicker than the 300, but over the long term, they would look much the same, except for the occasional spike from feeding or snails/fish dying and muddying up the water, etc. But a larger (wider) scrubber or a higher flow scrubber in general would (should) fix this issue.

Exactly! The time issue is key. If the rate of export is not sufficient, you will get an accumulation. The wider screen should have a higher flowrate due to the linear screen area.

To borrow an old marketing line.... Wider is better :lmao:

I suspect that there is a flow min/max range that will provide optimal growth, as well as an optimal LxW ratio (residence time will also matter)

 

[_shorty_]

You can see the red and blue from my new 18$ 18w led in the flood light style.

Where'd you get that? I haven't looked at what's available for a while...

 

[_shorty_]

It is so thick that the only areas that do no have any algae are directly in front of the LEDs. This does not seem to affect growth, however. But I do have 6x 660nm at 2" on center, so there is likely still plenty of light getting through.

So the intensity of the LEDs being the main factor there then. My 1W LEDs - even though plenty of light corporately, are not enough intensity individually to promote what SM is mentioning. That makes sense.

 

[Floyd R Turbo]

Yeah, if they're 1W then they might only have a small circle in front of them that is inhibited from growth. Even with a diffuser, I have about a 1-1.5cm circle in front of mine.

 

[moatdaddy]

Shorty. I got mine from eBay. Don't but it yet its on day 3 of testing. . I think I did a par 38 search.

Dear Santa Monica. Your logic is not sound. If turnover is not important than why do skimmers, a proven technology, increase in size with tank size? To me it's because there is more to it than your small product that is inefficient unless you have a bunch that can service a large tank. If I ran the Atlanta aquarium and feed 2 cubes of food would you still recommend your formula, 100000 gallons with two cubes of food would not be effective.

 

[_shorty_]

I will also note: DO NOT USE HAGEN TEST KITS. I bought a master kit when first starting this tank up because it was cheep. Most reviews just said they were difficult to read except near 0 readings. I thought that would be fine. NO, NO, NO, NO. I've been testing PO4 under .25 since the tank finished cycling. Previously, almost 0 with the ATS, and I knew it had crept up to around what hagen read at about 0.25ppm while using the UAS. I purchased a hanna PO4 checker, and 0.79!!! I was so upset with Hagen. Fortunately I haven't lost any SPS to these false readings, YET.

Okay... so this test was off.. I'm not sure what happened, but upon retest it was .25, which I'm still not happy with, but hey - it's better than .79. So I'm not as mad at mr Hagen as I once was...

 

[JohnnyB in SD]

JohnnyB in SD

Could you please explain these in a little more detail?

1. spaced approx 2.25" on center

2. you might consider designing something with 1.5 or 2x the emitter density.

May be a pic? Thanks Dave.

Hey Dave, how is it going? Good to see you trying to make some progress.

2.25" on center means I mounted them with about that much distance between centers of each LED on the the heatsink. Rough layout attached for expedient reply, was not exactly my final. Your distance between centers should be closer depending upon how many you end up using.

In the example with 23 LEDs, 1.5 or 2 times the density would mean using 35-46 in the same 8x16 area. I suggest this in your situation as you are mounting them about twice as far from the screen as I did. I believe it is better to build with more, rather than not enough, as they are relatively inexpensive & you can dial them back if needed. But if you don't have enough light, you'll need to find a way to retrofit more.
Looking back, I see you are mentioning a 6x8 screen, which is 37.5% of the area in my 8x16 example. So I'm recommending 35 or 46 x 0.375 = 13-17 LED's (per screen side) for your application, something like the second example. I would base exact number on how their forward voltage calculates out with the drivers you use.
Also, the heatsink can be slightly smaller than the screen dimensions, as you won't be mounting LEDs directly on the boundaries of the screen. Maybe a 4.850" or 5.375" x 6" sink for 6x8 screen?

Naturally, I am only telling you what works for me, and I can say it works excellent. I based my build on information & advice I mostly received from Floyd, so I recommend his input as well.
Hope this is helpful.
Best of luck to you.

 

[JohnnyB in SD]

After replying to you, I read other posts & see that moatdaddy is trying out a new LED that MAY be usable for your application. You might want to see how that works out for him, could be a whole lot less trouble for your situation IF it is effective.

 

[ezhoops]

Wow, i read first 30 pages and then began skipping around. Few questions:
How large of a screen for a 60 cube
What type of led can i use for it

Great thread i will be using an ats for a new tank setup soon

 

[moatdaddy]

Well mine was 18 bucks per light 7 bucks for the housing. It's working but there is a mix so I need to buy a second one to get concrete evidence. I will have an answer for you guys in a couple of weeks because right now my led is beside a cfl flood light. It's growing the same but not sure how much of that is due to the cfl floodlight.

Oh and zero wiring. I have used acrylic shields then switched to syran wrap. Both ways the lights still got moisture. At least with syran wrap I have more in tub flow.

 

[Floyd R Turbo]

Wow, i read first 30 pages and then began skipping around. Few questions:
How large of a screen for a 60 cube
What type of led can i use for it

Great thread i will be using an ats for a new tank setup soon

Start by looking over the "basics" posts, as noted in my signature.

LEDs: use 660nm Deep Reds. If you want to add a few blues, you can, but they are more powerful so I run them at half power by wiring them in parallel within the series. It helps to have matched LEDs for this. I get Philips Luxeon ES from Steves because they are always the same.

 

[SantaMonica]

Air Pump Recommendations for UAS® upflow algae scrubbers®. Having bought and tried all of these, here are the best ones:


Flow (highest to lowest):

Coralife Super Luft... TONS of flow for multiple outlets or multiple scrubbers
Tetra Whisper 300... High flow if both outlets are combined into one
JW Aquatic Fusion 700... High flow if both outlets are combined into one
Tetra Whisper 150... Good flow for one outlet
Coralife Luft (regular)... Good flow for one outlet


Noise (most to least):

Coralife Super Luft... (Loud; vibrates)
Coralife Luft (regular)... (Vibrates)
JW Aquatic Fusion 700... Slight vibration
Tetra Whisper 300... Silent
Tetra Whisper 150... Silent


Size: (big to small):

Tetra Whisper 300... Large
JW Aquatic Fusion 700... Medium
Coralife Super Luft... Medium
Tetra Whisper 150... Medium
Coralife Luft (regular)... Small


Cost (most to least):

Coralife Super Luft
Coralife Luft (regular)
Tetra Whisper 300
Tetra Whisper 150
JW Aquatic Fusion 700

Overall winner for a single UAS scrubber used at home: JW Aquatic Fusion 700 (also is the only one with adjustable flow)
Overall winner for multiple UAS scrubbers if noise if ok: Coralife Super Luft

 

[scolley]

If you've already got an air pump, and an upflow scrubber means adding a new pump, it may be time to consider a single, powerful pump for all your airflow needs. Years ago I bought one of these Mid-sized Diaphragm Pumps from Jehmco. A bit pricey, but some of the best value for money I've ever gotten. Not too big, dead silent, enough blow for several tanks, and works for years with no maintenance. But you will need a decent gang valve to use it though, as you'll likely be bleeding off unused air.