Algae Scrubber Basics

[flixxx]

I just made my first attempt at a vertical scrubber and things are not going to well.

I followed Floyd's blog and first measured my flow: 360 GPH.

I only need a 24 square inch setup (one sided lighting) so i opted for a 5 inch slit.
I replumbed my overflow and crated the 1/8 inch slit on a horizontal pipe

The issue i face is that the water comes out of the slit but comes out angled to the right so only half the screen is getting wet at a 45 degree angle.

I thought maybe the hole wasn't straight so i made a new one but i face the same problem (I also made a third one with only a 4 inch slit thinking the water didn't have time to fill the PVC).

What could be the cause? Too much flow?

[spamreefnew]

Sounds normal. The flow will start to fall straight down in a few days when the screen gets a biofilm on it. You can also widen the slot ,but only slightly. I would just start by waiting and if the flow still goes off to the side after you have some growth then take a file or sandpaper to the slot.

[Floyd R Turbo]

5" x 35 GPH = 175 GPH, you're at nearly double that. So you're going to end up with a lot of pressure which might result in excessive arcing

[flixxx]

Originally Posted by Floyd R Turbo

5" x 35 GPH = 175 GPH, you're at nearly double that. So you're going to end up with a lot of pressure which might result in excessive arcing

What's the range of GPH per inch? I only read the minimum, I never hear about the max to have keep presure in check and quieter.

[Floyd R Turbo]

Once you get much over 50 GPH/in you hit a point of diminishing returns, IMO

[karimwassef]

So if you're running 4000 gph with surges of double that in bursts, you need 160" of width?

That would require running the width of an 8' tank x 2 sheets?

Sorry - new to the topic

[flixxx]

Originally Posted by karimwassef

So if you're running 4000 gph with surges of double that in bursts, you need 160" of width?

That would require running the width of an 8' tank x 2 sheets?

Sorry - new to the topic

I'm thinking of leaving my 5 inch slit and adding an elbow vertically with a ball valve to control the rest of the flow into the sump.

Floyd, would that be an option?

[sensei]

Hello all,
I have never used an algae scrubber, but I like the concept.
Would it be recommended to have both a refugium and an algae scrubber in same tank?

is this the right canvas for the scrubber:
http://www.amazon.com/gp/product/B00...ilpage_o01_s00

Thanks

[hkgar]

Originally Posted by flixxx

I'm thinking of leaving my 5 inch slit and adding an elbow vertically with a ball valve to control the rest of the flow into the sump.

Floyd, would that be an option?

Not sure, but I think your problem may be that that your flow is through the pipe with the slot - thaat is the end of the pipe is not capped. I had that similar flow problem when I plumped into the pipe coming from my overflow and used an elbow to direct the excess flow into the sump. I now have plumbed into the return line and have an end cap on the pipe. I control flow with a gate valve - do not use a ball valve. I do have a ball valve on the line also to be able to shut it down for removal and cleaning, without needing to readjust the flow after cleaning.

[karimwassef]

Either it takes all the flow or I can use the surge overflow siphon line. It would have zero flow then very high flow, etc... The only worry would be nighttime when it would receive no flow for 8 hours. Might dry up and die?

[Floyd R Turbo]

Originally Posted by flixxx

I'm thinking of leaving my 5 inch slit and adding an elbow vertically with a ball valve to control the rest of the flow into the sump.

Floyd, would that be an option?

Yes, there is an example of something along these lines recently in this thread but that's kind of like looking for a needle in a haystack. An elbow after the screen is fine, but what you want to pay attention to is making sure that the growth can't really clog up the slot/screen junction, because there is no pressure to prevent this from occurring. So what you would need is some kind of light blocker, or you make the scrubber extra tall and only light the bottom part of the screen. So your scrubber in this case would have an "active" area. You can also leave the upper un-lit area smooth (don't rough it up) and this will help prevent algae from growing as well. Scrubbing it with a stiff brush during cleaning will keep it free of growth.

This situation is actually one where making the slot a bit wider can help, because low-pressure flow might be less just dropping through the slot/screen junction via gravity. But a little extra slot width goes a long way.

Originally Posted by karimwassef

So if you're running 4000 gph with surges of double that in bursts, you need 160" of width?

That would require running the width of an 8' tank x 2 sheets?

Sorry - new to the topic

If you wanted to match the screen width to the total flow, then yes. But as you can see, that results in a rather silly size!

Better to size it per what you need, then pump feed it, or via return plenum along with reactors/etc, or as described above

Originally Posted by sensei

Hello all,
I have never used an algae scrubber, but I like the concept.
Would it be recommended to have both a refugium and an algae scrubber in same tank?

is this the right canvas for the scrubber:
http://www.amazon.com/gp/product/B00...ilpage_o01_s00

Thanks

That looks like the correct material. Rough it up well!

As per scrubber vs fuge, lots of factors to consider. If you have a huge tank and a small fuge, probably could run both. smaller tank, small fuge, the scrubber might out-compete the fuge. But then again that depends on the strength of the scrubber, and the fuge.

[karimwassef]

Can it run dry occasionally? The rocks at the beach seem to be ok being exposed for hours at a time and covered in a layer of slime and hair algae.

[sensei]

Thanks for your answer Floyd,

I am planning a new 450 gal DT mixed reef, and the fuge will be 30gal aprox, so it may be considered small. I believe I will feeding about 2 sheets of nori and 6 cubes of myses per day. If I understood correctly I would need eight pieces of 12 square inches of screen illuminated on BOTH SIDES for such load, but since I will be doing a fuge of 30gals, I was thinking of doing 2 or of 12 square inches of screen for the algae scrubber.
please tell me what do you think.

thanks

[Floyd R Turbo]

Originally Posted by sensei

Thanks for your answer Floyd,

I am planning a new 450 gal DT mixed reef, and the fuge will be 30gal aprox, so it may be considered small. I believe I will feeding about 2 sheets of nori and 6 cubes of myses per day. If I understood correctly I would need eight pieces of 12 square inches of screen illuminated on BOTH SIDES for such load, but since I will be doing a fuge of 30gals, I was thinking of doing 2 or of 12 square inches of screen for the algae scrubber.
please tell me what do you think.

thanks

I don't think you meant you would need 8 separate screens, but you have the right idea I think. You would need a screen that could handle 8 cubes/day of feeding

So that's 8 x 12 = 96 sq in of area (LxW) or about a 10x10 screen, with at least 50W of CFL per side (and up to 100W) or something like 25-50W of LED (pre-manufactured fixture) on each side

Originally Posted by karimwassef

Can it run dry occasionally? The rocks at the beach seem to be ok being exposed for hours at a time and covered in a layer of slime and hair algae.

I suppose, but why would you want to? Algae only filters when there is water running over it.

[sensei]

[QUOTE=Floyd R Turbo;24040370]I don't think you meant you would need 8 separate screens, but you have the right idea I think. You would need a screen that could handle 8 cubes/day of feeding

So that's 8 x 12 = 96 sq in of area (LxW) or about a 10x10 screen, with at least 50W of CFL per side (and up to 100W) or something like 25-50W of LED (pre-manufactured fixture) on each side
QUOTE]

Thanks Floyd,
now, since I will have a fuge of 30gal would it be better to do only screen for half the load?? I mean one of 10 x 5= 50sq in of area or should I stick withethe 10 x 10??

can it happen that using both the algae scrubber of 10 x 10 and the 30 gal fuge, they consume to much nutrients to levels that are not apropriate for growing corals?

is the size of the algae scrubber coralated to the levels of NO3 and PO4 in the system? if I make the screen bigger would I get lower level of nutrients in water and visceversa?

thanks again for your help

[Floyd R Turbo]

A larger screen (and lights, flow, etc) would tend to grow more algae, but you can control the growth by adjusting the flow, photoperiod, and intensity.

If you have initially elevated levels of N and P then a larger scrubber would help you lower these better.

But IMO if you have a very elevated level of nutrients, it's better to get the scrubber growing while you take other steps to lower the N and P, and then when the scrubber is running at full strength, it should keep these levels in check. Relying on a scrubber to solve a nutrient problem can work, but sometimes very high nutrient systems take a long time to get under control with just a scrubber. If you have a long-term problem then it could take some time as the scrubber "mops up" the mess, even if you do water changes and run GFO etc.

There are a lot of factors that determine growth so these aren't hard-and-fast rules, but more of a general guideline to get you in the ballpark so it's hard to say that XYZ scrubber is going to do ABC for you.

[sensei]

Floyd,
above you said that:
"you can control the growth by adjusting the flow, photoperiod, and intensity"
do you have to be changing these parameters based on your N and P levels, or once algae scrubber growing green hair algae you just leave it alone and just clean it every week?

[Floyd R Turbo]

Well I just leave them alone and clean when needed. At this point I don't even monitor N and P, I might test once a month, except for my personal tank (120). I added 10 anthias and 4 pajama cardinals and then tested a month later (after increased feedings) and I had elevated N and P for the first time in a long time. So I had to tweak the scrubber so that I could run higher flow.

[sensei]

Thanks a lot!
I will do the algae scrubber and get back to you

[SantaMonica]

Can it run dry occasionally? The rocks at the beach seem to be ok being exposed for hours at a time and covered in a layer of slime and hair algae

Beach algae has adapted to this, but scrubber algae has not. Any dry time starts to kill it.

"you can control the growth by adjusting the flow, photoperiod, and intensity" do you have to be changing these parameters based on your N and P levels

Algae self-adapts to the nutrients levels. If you every over feed one day, the next few days will see large growth.


Scrubber vs Refugium:

Scrubbers compared to refugiums

If you are starting a new tank, then the obvious difference is that a scrubber gives you the option of not having a fuge at all because an upflow scrubber can be placed on top of, in, or behind, the display. There are other uses for a sump/fuge of course, but we'll only cover the filtration concerns here.

A not-so-obvious difference is that a scrubber, if run together with a fuge with macros, will kill the macros even though the macros are much larger. This is because the scrubber thinks the macros are nuisance algae. Some people do run both together without killing the macros, but this is just because their scrubber is not strong enough, and actually the macros might even be slowing down the scrubber because the scrubber thinks it has to remove the macros, along with the nutrients in the water and the nuisance algae in the display. However if this works for them, good.

But assuming you have to decide on either a sump/fuge or a scrubber (not both)...

o Filtration with algae is proportional photosynthesis, which is proportional to Light X Air Water Turbulence Flow X Attachment. Meaning, stronger light grows more algae; stronger air/water interface turbulence grows more algae; and stronger attachment lets more algae grow without it detaching and floating away. A scrubber is thus designed to maximize Light, Flow, and Attachment.

o The main problem with macros in a refugium is the self-shading that the macros do. Any part of the macro which is not directly in front of the light at any moment is not filtering. And any macro inside of a "ball" of macro (like chaeto) is self-shaded all the time. Only the surface macro that is directly in front of the light is doing any real filtering. A scrubber is designed to have all the algae in front of the light at all times. Rotating the macro does not solve the problem, because the time that the macro is rotated away from the light is time that the macro is not filtering. This is why it takes a much larger size of chaeto to do the same filtering as a scrubber.

o Self-flow-blocking is another problem of macros in a refugium, for the same reason as light-blocking. And the thicker the "ball" of macro, the worse the flow-blocking.

o Particle trapping is another result of a ball of macro. These particles need to cycle back around to feed the corals, but instead they get trapped in the macro and they rot, and in doing so they block even more flow and light.

o With a scrubber, there is very little water standing in the way of the light. Also, the light is (or should be) very close to the scrubber... 4 inches (10cm) or less. The power of light varies with the inverse square of the distance, so going from 8" to 4" actually gives you 4X the power, not 2X. And the nutrient removal power of algae is proportional to the power of the light, because it's the photosynthesis that is doing the filtering.

o Rapid flow across the algae in a scrubber gives more delivery of nutrients, compared to the slow moving water in a fuge. Filtering is proportion to nutrient flow.

o The turbulence of water moving over the sections of algae in a scrubber help to remove the boundary layer of water around the algae. This boundary layer slows the transfer of metabolites in and out of the algae. There is no turbulence in a fuge (if there were, you'd have waves and bubbles). The interface between the air and water is what provides the most turbulence and boundary layer removal; there is no air/water interface in macros.

o Scrubbers do not let food particles settle like a refugium does; most particles flow right out of the scrubber.

o Scrubbers do not (if cleaned properly) release algal strands into display, like chaeto does.

o Scrubbers do not go sexual, like caulerpa can.

o Scrubbers do grow lots of pods; more than was previously thought, especially if not cleaned with freshwater.

o Scrubbers don't, obviously, provide a place for snails and crabs, etc.

However, if you already have a sump with an empty compartment, and you don't mind using all of it and putting a light over it, then maybe it's easier and cheaper to try macros first.

[jason2459]

I found that diminishing rate of return on the flow. Past two weeks I had my ATS pump on full for the first time and it did not work out so well.

Front


Back



So I cleaned it off and throttled the flow back a bit again


So I think I'll set it to this again for a couple weeks and it should come right back. I don't know if I should increase the lighting period a bit or wait a couple weeks for it to produce that nice thick mat again.

Now on the awesome side my ORP plummeted during this time frame and is about 380 just before the ATS LEDs turned off this morning and is at 368 right now. So I kind of was assuming something wasn't right and my theory was right. Ha!

This I think makes a much more solid case the ATS is directly effecting the ORP levels. Now to see if it at least stabilizes over the next two weeks. I'll have to pull my ORP graphs for the past couple weeks later.

[jason2459]

Looks like the graph can only do 7 days at a time.

So, here's the stats for the past 7 days which has been hovering around 350-360's the past few days on average during the lows.

Overall Minimum: 346 Average: 365.15 Maximum: 383
Selected Minimum: 346 Average: 365.15 Maximum: 383

But here's a good graph representing what I was watching and shows the dramatic drop I mentioned above. You can see it going up every night with the LEDs on but it wasn't keeping up with the daily drop.

[sensei]

Originally Posted by SantaMonica

Scrubber vs Refugium:

Scrubbers compared to refugiums

A not-so-obvious difference is that a scrubber, if run together with a fuge with macros, will kill the macros even though the macros are much larger. This is because the scrubber thinks the macros are nuisance algae. Some people do run both together without killing the macros, but this is just because their scrubber is not strong enough, and actually the macros might even be slowing down the scrubber because the scrubber thinks it has to remove the macros, along with the nutrients in the water and the nuisance algae in the display. However if this works for them, good.

I do not understant the statement "the scrubber thinks the macros are nuisance algae"??

If understand correctly, the scrubber and the macro in fuge will both compete for nutrientes in water, and it seems that the scrubber has more potential to absorve the nutrients and can starve the macro algae in fuge as well as green hair algae in DT. please let me know if I got the concept.

Thanks

[Floyd R Turbo]

Yes, you have it right.

[sensei]

Floyd,
If you oversize the algae scrubber, is it possible that tha algae will consume to much nutrients to a level that is not desirable by the corals??
I ask because I understand that before the size was based on the tank size and not the feeding load and I do not know the results of such scrubber vs the ones size based on the feedings?

thanks a lot