Algae Scrubber Basics

[Swanwillow]

my first one was made with the side of a plastic cutting board. Worked well.

 

[parrotchute]

I don't think the algae would effectively grip onto it.

 

[Floyd R Turbo]

Could I create a really simple ats by using a piece of acrylic and just having the water flow on it into my refugium? It would only be one sided but it wouldn't be as complicated to build.

You could, however it it difficult to rough up acrylic enough. The algae will form a mat that can be easily peeled away by water flow. If you're set on using the acrylic to 'guide' the water, then just lay a roughed-up piece of the #7 plastic canvas on it to grow the algae. Single-sided rules apply.

I understand from the pics & info you've already provided, thank you very much.
The advantage of a closed bottom with the drain system is that water can get trapped to encourage 3D growth?
One option I was considering, but have never used personally, is an open bottom with longer screen into the sump. Would be silent? Would water drip off the acrylic panels and make noise if they weren't also submerged at the bottoms? Microbubbles? What are the downsides?
Is 3D growth much more efficient to deal with the whole closed box/drain thing?

Yes, the 3D growth allows the algae to 'trap' water, but it still flows through the mat so it keeps the layer near the screen alive and moves fast enough to breach the boundary layer (where the nutrient exchange happens at a cellular level), and it also allows the algae to grow long without pulling off the screen.

Leaving the bottom of the box open to the sump would surely be quiet. If you made a box with no bottom and it was thin, say 1/2-3/4" from the screen on each side, and you had good green growth, it would likely grow thick enough to touch the wall of the box, and this is pretty much all you need to start the 3D effect, it takes off on it's own exponentially at that point. I'm thinking that someone has done this at some point...somewhere in this thread or on another site...

 

[Floyd R Turbo]

I will upload pics from my cell phone of the first week's harvest of the modified scrubber - phenomenal growth! I got a solid mass of green this week, and it was as much or more than the previous record growth from this system on 30% less screen material. I attribute this to better slot (more even flow) better flow, and better use of lights (the screen near the ends of the lamps never got really green, mostly grew red/turf)

Also, the P tested at 0.01. Previously I have not been able to get that down below 0.09 due to Nitrate limitation, so we'll see if it continues along this path.

 

[Floyd R Turbo]

Here is an important tidbit of information that was posted on another site after I posted about the increase in growth:

Yes the smaller screen size, for a give amount of nutrients, causes the growth to grow "out" instead of "sideways" because it can't grow sideways because there is no more screen. So by growing "out" it gets closer to stronger light, and gets more 3D flow, which increases filtering even more.

When there is endless screen available, it just grows sideways and never gets closer to the light (actually, it gets farther from the light), and it stays 2D. In the ocean this endless-area does not matter, because growing sideways does not reduce the light

Given that information, anyone who is having trouble getting green growth, especially around the edges, should consider trimming down the width of their screen to eliminate or reduce the area where the brown/red growth is occurring. This usually means cutting a new slot tube, or somehow sealing up the ends of the slot (which can be done rather easily by cutting a patch out of spa-flex and welding it on, or other patching techniques for leaky PVC joints, for instance).

Trimming the screen down to help spur green growth works for several reasons:

1) As mentioned, reduces areas of non-green growth
2) Increases flow per inch
3) Increases light wattage/sq in (more accurately, eliminates low-wattage areas which tend to grow brown/red algae)
4) forces green algae to spread perpendicular to the screen (3D) versus along the screen (as stated in the quote above)

So if you're experiencing a lot of red/brown growth around the edges of your screen, consider trimming off a small portion of your screen and see if that makes a difference. I would suggest a 10% width reduction to start, and give it a week or two, don't change anything else (feeding, etc) and pay attention to the before/after.

 

[6Speed]

I have a very limited amount of space in my sump and cabinet so I am going to have to use led's. the screen area I have to work with is only about 9" wide by 5" tall and the max space I have for a light is 3" deep by 9" wide by 5" tall. this is only a 20 gallon tank and the sump adds another 5ish gallons to the water capacity.

an off the shelf nanoglo refugium light fits perfect with plenty room to spare and I'm considering building or buying something similar but more powerful/dimmable with the correct color LEDs. any recommendations?

 

[Floyd R Turbo]

nano glo looks like 6500K so that's not the right spectrum. I would just DIY it and use 660nm LEDs. Also a 9x5 screen is 45 sq inches, which is great if you plan on feeding 4 cubes a day into your 20g. I'm guessing not. Use the new feeding based size guidelines. I'm guessing you're probably only going to feed about 1/2 a cube per day, which means your screen only needs to be 6 square inches. Realistically, it might be more difficult to run a screen that small, so I would go 12 sq in. I have to look for the link but there are some people using a LED chip that has 3 660nm LEDs on it and it works well. Would be good for a small build like yours probably.

 

[6Speed]

awesome. yes I was thinking I wouldn't need to utilize that large of a screen area. I love the idea of having a small screen doing such a big job for my tank!

if you find the link let me know. I'd love to see what small led setups diy'ers have come up with.

 

[Floyd R Turbo]

The link is to another site that is blocked so I can't post or PM the link to you. Sorry.

 

[parrotchute]

I wasn't getting good growth on my scrubber. It was brown-slimey algae and too spread out.
So, taking some advice, I raised the lights up to cover just the top 5", cut the screen in half to "concentrate" the algae's growth area.
What do you guys think? Think that will help?

I figure as my system bioload grows, I can remove some of those boards and just stack another pair of lights, and increase my screen size.

Thanks for any feedback, I'm struggling a bit!

-Alex

CURRENT GROWTH:

BEFORE:

AFTER:

 

[Floyd R Turbo]

Looks good, give it a couple of weeks.

 

[parrotchute]

Looks good, give it a couple of weeks.

Thanks Floyd, will do!
Sidenote - getting a lot of suspended crap in my tank, looks very yellowy and turbid.
How do most people with a scrubber deal with suspended detritus that a skimmer would usually sift out?

 

[Floyd R Turbo]

After you scrape the screen off, do you rinse it thoroughly in tap water and make sure it's running clear?

 

[JohnnyB in SD]

I wasn't getting good growth on my scrubber. It was brown-slimey algae and too spread out.
So, taking some advice, I raised the lights up to cover just the top 5", cut the screen in half to "concentrate" the algae's growth area.
What do you guys think? Think that will help?

-Alex

CURRENT GROWTH:

AFTER:

What you did makes good sense. I'm sure many, like me, are watching to see how those lights ultimately work out.
My water is very clean & clear, maybe your algae isn't holding onto the screen very well. Probably the previous weak lighting? I'm sure the screen is roughed enough.
Is there a reason you're using 2 extra 90° elbows to feed the screen on the opposite end from the pump?

 

[rndmcnflct]

I wasn't getting good growth on my scrubber. It was brown-slimey algae and too spread out.
So, taking some advice, I raised the lights up to cover just the top 5", cut the screen in half to "concentrate" the algae's growth area.
What do you guys think? Think that will help?

I figure as my system bioload grows, I can remove some of those boards and just stack another pair of lights, and increase my screen size.

Thanks for any feedback, I'm struggling a bit!

-Alex

As the poster above me mentions, every 90 you have restricts flow. Having four when you only need two is silly. Given that the algae in your first pic is growing right near the slot, where the flow is the highest, and nowhere else, overall flow rate might be an issue. If it doesn't grow with your current tweaks, I would replumb to two 90's and shorten the screen and slot.

 

[Floyd R Turbo]

It looks to me like he made it that way so he could get to the union and maybe there wasn't room for the pump on the near side or something. Either way, I agree, reducing the 90s would help increase flow, which may or may not be an issue.

Also, I know you've got a nice clean neat box made for the taller screen, but it would probably help to cut the box down a bit. Shouldn't be that hard, just run it through a table saw and make new end notches. Make it so that the bottom of the screen is underwater. I'm guessing this is running pretty loud right now with that 3-5" fall off the bottom of the screen. Not necessary, just a thought.

 

[parrotchute]

After you scrape the screen off, do you rinse it thoroughly in tap water and make sure it's running clear?

Yes - but I do have a lot of short, brown tufty (not quite GHA) growing on the backwall of the tank, so maybe it's detaching and yellowing the water? Probably...

Is there a reason you're using 2 extra 90° elbows to feed the screen on the opposite end from the pump?

It was for accessibility so I could easily get at it from the front of the sump. Otherwise I gotta somehow reach around the back to get at the union. Do you think 2 more 90's is actually restricting flow that much?? I can try a redesign this weekend, but maybe when I get a chance I'll run a flow test and figure a GPH for this set up. I probably should have done that already! I SHOULD have between 500-600GPH if my calculations are correct, with a 14" slot looking to have 490GPH.

 

[parrotchute]

It looks to me like he made it that way so he could get to the union and maybe there wasn't room for the pump on the near side or something. Either way, I agree, reducing the 90s would help increase flow, which may or may not be an issue.

Also, I know you've got a nice clean neat box made for the taller screen, but it would probably help to cut the box down a bit. Shouldn't be that hard, just run it through a table saw and make new end notches. Make it so that the bottom of the screen is underwater. I'm guessing this is running pretty loud right now with that 3-5" fall off the bottom of the screen. Not necessary, just a thought.

Yup, that's the reason.
I want to keep the box as is for now, since I want to be able to increase the size of the screen as my tank grows. It's a little loud, but it doesn't bother me! And don't I want to avoid a longer screen (i.e., making it long enough to tough the water)? In order to "concentrate" the algae and prevent it from spreading out?

I'll run a flow test tomorrow and get a better number.

Trying to figure out how close these LEDs need to be, too. I think they're pretty bright so I might back them off a little bit.

 

[Floyd R Turbo]

I would not back them off, I would put them as close as you can without burning. If you start to get yellow growth, cut the photoperiod back until you get green, but not so much that you get brown/slimy growth. This goes in hand with the high-light screen technique which is meant to power through to the green algae and required half the photoperiod. It is my theory that the LEDs do this, so I would cut your photoperiod back to 12 on 12 off for a start and see if you start getting green growth.

Just an idea for you, but you could cut a 1.5" or 2" pipe (as large as can fit in the box) lengthwise and make a trough at mid-level in the box that allows the bottom 1/4" or so to be submerged, then support it on the ends with a tee and vertical drop to an elbow. This would create a starting place for 3D growth and divert the water sideways to the tees and then down to the bottom of the box via the elbows.

The 3D growth really takes off when it has a place for the water to get trapped. With a box that has a bulkhead at the bottom, it takes longer for the algae to 'fluff up' or whatever you want to call it since the box is very wide, and if there's no 'stopping point' for the water flow, this will not encourage 3D growth very well.

But first, you need to start getting green growth. That is step one after your screen is cured (which yours looks like it is - 4-6 weeks old at least, right?).

Make sure your flow is adequate and your slot is straight and even width and the screen fits in loosely (not pinching).

Also forgive me if you have posted this already, but what is your N and P at?

 

[parrotchute]

Thanks for all the help Floyd - I'll do that with my lights.
So you're saying for the 3d effect to take place, it's best to have the end of the screen resting in a small pool of water so algae can grow out from there? Once I start growing I'll try to make a little trough like that.

Yup, it's at about 5 weeks now.

N/P is 0 as of last week. I'll retest tomorrow.