Algae Scrubber Basics

That's what I thought but I couldn't recall if you had posted that or not. I would put a diffuser on that when the screen is brand new, and leave it there for at least 2 weeks or until you get thick growth that stays in the holes after scraping (up to 6 weeks, depending on how well you rough up your screen). You can put the fixtures pretty close with the diffusers in place. After the screen is mature, you can take the diffusers off, or you can cut them down a bit so they are only a few sq in and right in front of the chip, that would be an intermediary step to fully removing.
 
Does it hurt if the screen is too big? Or should I just purchase 1 light and make it one sided with a larger screen? Or switch to 2 -20 watt lights because the screen is only 6x6
 
Always go double-sided when possible. Light from both sides is important for sustaining growth longer for each growth cycle.

I think whatever multichip you get will still create a hot spot. To determine the mutlichip wattage, I have to do a little math for you here. If I were to go by my rule of thumb for LEDs, which is one 3W 660nm Deep Red on each side of ever 4-8 sq in of material. To convert that to watts for comparison, each LED has a Vdrop of about 2.2-2.4V so at 700mA the actual consumption of each LED is more like 1.5-1.7W. Let's take the low number to be safe.

So that means for a 6x6 screen, using the high-intensity number, that's 6x6 = 36, 36/4 = 9 LEDs, 9x1.5 = 13.5 actual watts (consumed). For the low-intensity, 6x6=36, 36/8 = 4.5 LEDs, 4.5x1.5 = 6.75 actual watts. Those numbers are for each side.

In the Multi-chip fixtures in question, they use both red and blue - you mainly care about the reds. Ignore the chip counts, because they are using 1W chips. But just like the 3W chips, 1W does not necessarily equal 1W consumed, but the output ratio of "rated" to "consumed" is probably a little better. So if you were conservative and considered the "20W" fixture to be more like 10W consumed (by the LEDs, ignoring the driver losses) you would probably be safe with that assumption. That's 16 reds, "de-rated" a bit, and the blues are supplemental as far as we are concerned, so I really do not tend to factor their presence into the overall "wattage per area" calculation. There are only 4 of them so that is a good ratio and I don't feel it affects the calculation or increases the chances of photosaturation (blues are more intense at the same drive current)

That means that if you had a 6x6 screen and used the 20W fixtures, you would probably fall right in the middle between the "high" and "low" intensity ranges. Throwing the diffusers on would knock this down a bit. I usually recommend diffusers on a fixture that is individual LEDs setup for high intensity. In this case, since I am of the opinion that you should probably have some level of diffusion with the multi-chips, it's probably safer to go with the 30W fixtures + diffusers, for a 6x6 screen.

For a 6x4 screen, you could probably do the 20W fixtures and be pretty safe.

Hope that helps (and doesn't confuse too much)
 
What if I put a 20 watt on one side and a 30 watt on the other on a 6 x 6 screen. What is the down side on a larger screen. Just more to clean? Would it pull to much out?
 
That would be fine.

The purported downside is that if the screen is too big, the algae will try to grow over all of it but there won't be enough nutrients to "feed" it all, so it all sort of "starves" or turns brown, or rather, never grows very green and thick. How true this is I really couldn't tell you because there never has been any actual testing but it makes logical sense and seems to work, so right now we go with that recommendation.

I have been recommending that you don't size the screen much more than 2x larger than what you feed, unless you are dealing with a very large volume tank. Large volume is a secondary factor that IMO overtakes the feeding-based guideline at a certain point.

As for more to clean, no not really, it will just be more spread out. this also means that you are putting the same intensity of light over a larger area that grows thinner algae, which may also mean that it might tend to photo-inhibit faster. So adding the diffuser will reduce this effect, as will simply running a shorter photoperiod. So there are ways of reducing the "capacity" of a given scrubber, if you build it a bit too big.

For the record, there never really has been any sort of benchmark or scientific study of current algae scrubber designs so we have to use logic, reason, and interpretation of results gathered from those online who contribute to come up with recommendations.
 
I couldn't get my scrubber to shut up. I get a lot of HA growing on the rocks in my sump below my screen.

What are your thoughts on setting up a horizontal screen about 3-4 inches below the water surface in my sump. I have about 600gph thru the sump.
 
lokii_37 said:
I couldn't get my scrubber to shut up. I get a lot of HA growing on the rocks in my sump below my screen.

What are your thoughts on setting up a horizontal screen about 3-4 inches below the water surface in my sump. I have about 600gph thru the sump.
Click to expand...

Got a pic or a short video? There might be something you are missing.

If you want to block some light to the sump below the screen, and lessen the noise of water falling into the sump:

1) extend the screen to about 1" below the water level. I'm guessing you already are doing this and it's still noisy, so:

1b) take a piece of plastic canvas, the same width as your screen, and bend it to make a crease like a little rooftop. At the "peak" of the rooftop, use very small zip ties to secure this to the bottom edge of your screen. In this case the bottom of the screen can be above the water line, the further above the larger attachment "roof" you will want - you want the attachment to touch the water. This attachment will spread the falling water out in 2 directions, and water will also trickle through it, the but point is that it will deaden the noise. You can use the #7 mesh for this, or the #10 (smaller holes)

2) use black plastic canvas for the attachment if you want to block some light from getting to the sump. The larger the attachment, the larger area that you can shade.
 
Just got through testing a 2-LED scrubber which shines through the glass, with 30 square inches of attachment surface. You'd think the LEDs were way to weak for that size area.

First cleaning was brown slime; 2nd cleaning with some green hair; and 3rd cleaning was packed with green. And this is with just 5 chromis. So it got up and running really quick, and shows that in less-stringent situations, 2 LEDs can really grow well ( N=5, P=0.14 )

The LEDs were about 2.5 inches from the screen. And since they were lower power, they did not need to be shaded (reduced light) in order to start growing.
 
SantaMonica said:
Just got through testing a 2-LED scrubber which shines through the glass, with 30 square inches of attachment surface. You'd think the LEDs were way to weak for that size area.

First cleaning was brown slime; 2nd cleaning with some green hair; and 3rd cleaning was packed with green. And this is with just 5 chromis. So it got up and running really quick, and shows that in less-stringent situations, 2 LEDs can really grow well ( N=5, P=0.14 )

The LEDs were about 2.5 inches from the screen. And since they were lower power, they did not need to be shaded (reduced light) in order to start growing.
Click to expand...

Just to clarify SM, if you don't mind. This is the test screen where the actual second cleaning was not a cleaning and you just let it grow for another fortnight? And the tank is the one where you put lots of food in the tank which was decomposing on the tank floor? Or perhaps this is a test screen which you haven't posted on the tube?
 
SantaMonica said:
Yes same one.
Click to expand...

Seems like your getting through a few fish testing this scrubber. First you had 3, then upto 6, then down to 3 and now back upto 5. The attachment to the screen is not good and I'd be worried a chunk may block the relief hole. A strange point is that the two tufts of green algae are horizontally positioned whereas your lights look like they are vertically mounted, perhaps you could work out why? I would like to point out that nobody should ever toxify their tank just to grow a scrubber. Scrubbers should be made to grow in a healthy marine environment in my view, and not a sewage works.
 
So going off the numbers relating to food amount, is this correct:

I feed ~ 1/4-1/5th of a cube every other day for 2 clowns and a firefish.

A 2x3" screen would be 6sq", and 12sq"=.5cube/day. So this (2x3") would be able to pretty easily handle the 1/4 cube every other day I feed correct? Then I was thinking of getting one of the 10W LED flood grow lights for it off of ebay, or would that be too much?

I was thinking about making a floating one to put in my AC70. How would I suspend the screen on top of the water, ie make it float?
 
10 LED watts is way to much. A single 3w is fine.

You can float the screen by putting foam around it...
 

Attachments

  • P8.jpg
    P8.jpg
    75.3 KB · Views: 10
Haven't posted in this thread for a while, but a quick update is in order. My new 75g tank has been up and running with only a new ATS for filtration since 03/20/14. I am using the chinese LED floodlights I posted a few pages ago (the 40w version of this http://www.ebay.com/itm/22130724009...eName=STRK:MEWAX:IT&_trksid=p3984.m1423.l2649 except with only two blue LEDs) for lighting the ATS and so far I think it is going well.

Only a small amount of GHA left from my cycle in the tank, and it is very light green, almost yellow, in color and comes off the rocks with almost no effort when I touch it. I have only cleaned the screen twice, once this past weekend and two weeks prior to that. Each time there was a lot of GHA growth on the screen directly in front of the LED floodlight and a smaller amount to the sides of the light. So, I would say, there is not much light spill to the sides from the floods with them only being approximately 4-5 inches from the screen on each side.

In the past couple of weeks I have added all of my coral from my old Solana cube as well as the six small fish that I had. Everything seems to be going smoothly with the filtration. Once I sell or trade the remaining coral frags that are still in my Solana, I will be transferring the skimmer from that tank over to the 75g.

I will try to post a photograph of my set-up and the screen later if I can. So far, though, I like the LED floodlights and they seem to be workin well. Of course, I have nothing to compare them to as this is my first ATS!
 
Last edited:
Personally I've got loads of light overspill from my scrubber, but only growth on the screen.

11f9614f50b1ad35729b4335a638f24b_zpsea3e75fd.jpg


Edit - For what it's worth, the back of this sump has not been cleaned for 8ish years.
 
Last edited:
You must log in or register to reply here.

Similar threads

adova
300g DIY Acrylic Tank Recommendations
Replies
5
Views
355
griss
griss
Jyetman
All my corals and live rock now in my scrubber tank
Replies
2
Views
539
Jyetman
Jyetman
K
Carbon Dosing causes STN/RTN?
Replies
13
Views
719
Timfish
Timfish
D
Can I use Fiji 12 Sump skimmer compartment for cheat fuge?
Replies
7
Views
676
griss
griss
A
Fleece filter bypass problems (Innovitech X filter)
Replies
1
Views
240
Vinny Kreyling
Vinny Kreyling
Back
Top