Algae Scrubber Basics

[SkyReef]

Hi, SantaMonica: in a response to a thread by BlackWidow, at http://reefcentral.com/forums/showthread.php?t=2261943, you recently gave some specifications that I have questions about.

Scrubbers are sized according to feeding. Nutrients "in" (feeding) must equal nutrients "out" (scrubber growth), no matter how many gallons or liters you have. So...

An example VERTICAL upflow or waterfall screen size is 3 X 4 inches = 12 square inches of screen (7.5 X 10 cm = 75 sq cm) with a total of 12 real watts (not equivalent) of fluorescent light for 18 hours a day. If all 12 watts are on one side, it is a 1-sided screen. If 6 watts are on each side, it is a 2-sided screen, but the total is still 12 watts for 18 hours a day. This screen size and wattage should be able to handle the following amounts of daily feeding:

1 frozen cube per day (2-sided screen), or
1/2 frozen cube per day (1-sided screen), or
10 pinches of flake food per day (2-sided screen), or
5 pinches of flake food per day (1-sided screen), or
10 square inches (60 sq cm) of nori per day (2-sided screen), or
5 square inches (30 sq cm) of nori per day (1-sided screen), or
0.1 dry ounce (2.8 grams) of pellet food per day (2-sided screen), or
0.05 dry ounce (1.4 grams) of pellet food per day (1-sided screen)

High-wattage technique: Double the wattage, and cut the hours in half (to 9 per day). This will get brown screens to grow green much faster. Thus the example above would be 12 watts on each side, for a total of 24 watts, but for only 9 hours per day. If growth starts to turn YELLOW, then increase the flow, or add iron, or reduce the number of hours. And since the bulbs are operating for 9 hours instead of 18, they will last 6 months instead of 3 months.

If I feed only 1 cube per day--without regard to the fact that my tank is a small, 14-gallon BioCube--then the following specifications apply to my vertical ATS, using both sides:

• I should have an ATS screen that measures 12 sq inches, such that I have least (and more if possible) 35 gph flowing down the ATS Screen, per width-inch. Thus, if the screen is 4 inches wide and 3 inches tall, I should have a GPH of at least 140 gph (35 x 4) flowing down the screen. I will test it, but, in the meantime, I think I have at least double that flow (300+ gph), so I should be fine--unless you think that it is too much flow having a negative effect; and
• I should aim 6 watts at each side of the screen (totalling 12w) for 18 hours per day, or 12 watts per side (24w total) for 9 hours per day.

I have 23w bulbs. It seems like I need to find smaller watt bulbs? Is that right? Where can I get such small wattage in a bulb, 6 watts at 2700k? The lowest wattage that Home Depot sells is 12 watt and 13 watt CFL bulbs at 2700k. Would it simply be easier to use a 23w bulb against a 24 sq. inch screen on one side, rather than half the wattage on two sides of a 12 sq. inch screen?

Please let me know. Thank you.

 

[blackwidow]

Today I did my second scrubbing of the ATS screen and removed 200 Grams of black algae. What is this algae I have removed, it gives of a purple dye when rubbed between fingers???

 

[SkyReef]

First Test-Run of ATS Screen: Houston We Have a Problem

First Test-Run of ATS Screen: Houston We Have a Problem

I installed my very first algae turf scrubber today and gave it a test run. Wow. Not what I expected. There was Niagara Falls gushing everywhere around the screen with chaotic, turbulence. I thought perhaps the 1/8" slot might have been causing the problem by being too constricted and causing a backup of the water or its irregular ditribution. However, the 1/8" slot is well-made: straight and clean. It doesn't appear to be the problem. I thought that maybe my screen was jammed too far up the slot, but I doubt that is the problem, either.

Finally, I suspected that there was simply too much water flow in the ATS plumbing. I know the flow-rate rule: 35 gph per linear inch of the width of the ATS screen. My screen is 5" wide, and it should receive a water flow of around 175 gph. I hadn't tested the flow rate through the ATS rig, but I suspected it would satisfy the 175-gph minimum flow required.

So I removed the ATS screen and moved the rig to the bathtub, to test the actual flow rate through the ATS rig. The flow rate was quite strong, filling a five-gallon bucket every thirty seconds. That's 10 gallons a minute and 600 gallons per hour! The recommended flow of 175 gph is about 30% of what is actually pouring out now.

Hence, my latest theory is that the 600-gph flow is simply too much for a 5" x 1/8" ATS-screen slot. The best way for me to test this theory is to install a ball valve on the assembly and gate the flow down by up to 70%. Anyone else run into this type of problem when first testing out an ATS?

Please share your thoughts. Thanks.

 

[blackwidow]

I installed my very first algae turf scrubber today and gave it a test run. Wow. Not what I expected. There was Niagara Falls gushing everywhere around the screen with chaotic, turbulence. I thought perhaps the 1/8" slot might have been causing the problem by being too constricted and causing a backup of the water or its irregular ditribution. However, the 1/8" slot is well-made: straight and clean. It doesn't appear to be the problem. I thought that maybe my screen was jammed too far up the slot, but I doubt that is the problem, either.

Finally, I suspected that there was simply too much water flow in the ATS plumbing. I know the flow-rate rule: 35 gph per linear inch of the width of the ATS screen. My screen is 5" wide, and it should receive a water flow of around 175 gph. I hadn't tested the flow rate through the ATS rig, but I suspected it would satisfy the 175-gph minimum flow required.

So I removed the ATS screen and moved the rig to the bathtub, to test the actual flow rate through the ATS rig. The flow rate was quite strong, filling a five-gallon bucket every thirty seconds. That's 10 gallons a minute and 600 gallons per hour! The recommended flow of 175 gph is about 30% of what is actually pouring out now.

Hence, my latest theory is that the 600-gph flow is simply too much for a 5" x 1/8" ATS-screen slot. The best way for me to test this theory is to install a ball valve on the assembly and gate the flow down by up to 70%. Anyone else run into this type of problem when first testing out an ATS?

Please share your thoughts. Thanks.

I dont really follow the flow rate / cubes per day food rule as it wholey inaccurate for precise calculation of nutrient addition to your system via food intake especially if your feeding fish that dont eat cubes of food. For e.g. I have Puffers, Trigger, Angel, Morays Eels and the last thing they want to eat is Ice Cubes. My fish eat King Prawn, Mussels, Feeder Fish, Salmon Fillets you name it they eat it. I dont know the equivalent amount of cubes (half water / half food) of food I would need to add to my system to match the nutrient levels of 10 Mussels, 8 King Prawns or 20 Frozen Feeder Fish is ridiculous so I wont even attempt to calculate that hence the cubes per day rule fails for me.

From my experience so far for an Effective Algae Scrubber you need High Flow Rate, Large Scrubber Screen Area and Hi-Watt Intense Red Bandwidth Lighting (2,700K Warm White Bulbs / Red LEDs) will do. Of course every scrubber is different and thus the needs of each system vary from one to the next.

Me for example, I have a heavily stocked 125 Gallon System, thus my Scrubber stats are 500 GPH Flowrate, Screen Area: 16"x10" and Lighting currently: 2x 23 Watt Warm White CFLs (upgrading soon to 30W CFLs).
When I started the scrubber all stats were the same except my flow rate was 250GPH rather than 500GPH which is what it stands at now! When I doubled the Flowrate I noticed a 10 fold increase in algal growth on my scrubber for the same lights in a given time span. My Flowrate is 4 x my system volume!


This shows flowrate is important aswell as lighting.

For your system you have a 17 Gallon Cube? Running a 5"x1/8" Scrubber screen on a flow of 600GPH is way too much flow for such a small system volume, infact thats more than my scrubber is getting through a 160" ^2 screen.

Im running a flow rate of 4 x my system volume per hour, even at a reduced rate of 175 GPH your still running 10 x your system volume per hour through scrubber which is better than 600 GPH but still way too much. So your suspicion about it being too much was right, I think there maybe some errors in the flow rate / feeding rate (cubes per day) calculation which may need to be fine tuned to make it more understandable / applicable to systems like mine (FOWLR) that do not feed cubes per day but chunks per day instead .

Maybe guidelines on flow rate and feeding could instead of looking at a minimum flow per inch of scrubber screen i.e. 35GPH/inch could be readjusted to N x Tank Volume / Hour as the flow through screen where N is ANY REAL NUMBER.

Even more inaccurate being the feeding rule should perhaps be tweaked to look at nutrient levels so the higher the Nitrates / Phosphates in your tank the the larger the Flow, Scrubber Screen Size and Lighting Wattage has to be....

Something like that would make more sense to me, right now I run my scrubber of my own intuition and adjust where need be whether more less flow and light wattage.:hmm2:

 

[JohnnyB in SD]

I installed my very first algae turf scrubber today and gave it a test run. Wow. Not what I expected.
My screen is 5" wide, and it should receive a water flow of around 175 gph. The flow rate was quite strong, filling a five-gallon bucket every thirty seconds. That's 10 gallons a minute and 600 gallons per hour! Anyone else run into this type of problem when first testing out an ATS?

Please share your thoughts. Thanks.

I'm pretty familiar with this whole thread, and you are the first person I can recall having the "problem" of too much flow. But yes, if it's not a smooth strong flow over the screen, then you should dial it back until it's under control.
Are you feeding it from an overflow or a dedicated pump? Overflow's can be T'd to distribute some of the excess flow, or pumps down sized = less electrical consumption as well.

I wouldn't get too hung up on the whole cubes feeding thing. It's a general guideline to start from, not an unbendable rule. You will be able to gauge how much of what you can feed after it gets up to speed & you observe nutrient levels & livestock reactions.

 

[SkyReef]

For your system you have a 17 Gallon Cube? Running a 5"x1/8" Scrubber screen on a flow of 600GPH is way too much flow for such a small system volume, infact thats more than my scrubber is getting through a 160" ^2 screen.

Thanks, BlackWidow. Your response is very helpful. I'll dial down the flow and report back as to whether that helped. You make an interesting correlation between a higher water flow and a quantum jump in algae growth on your ATS screen. I'll keep that in mind and not dial down my water too much.

I'm pretty familiar with this whole thread, and you are the first person I can recall having the "problem" of too much flow. But yes, if it's not a smooth strong flow over the screen, then you should dial it back until it's under control. Are you feeding it from an overflow or a dedicated pump? Overflow's can be T'd to distribute some of the excess flow, or pumps down sized = less electrical consumption as well.

Thanks, JohnnyB. Your humorous observation that I am the only one with such a "problem," reminds me that trouble, indeed, follows me. Your observations make sense. The waterflow to the ATS screen is by means of an independent pump. I will test the flow again, after a ball valve has been installed, so that I can reduce the flow. I'm crossing my fingers here and hope that slowing the flow will produce a clean "sheet" of water, rather than a turbulent wash.

 

[SkyReef]

ATS Screen Now Working Fine (I Think)

ATS Screen Now Working Fine (I Think)

My ATS screen is now working fine and not overflowing with turbulent, splashing flow, after I reduced the flow from 600 gph to 180 gph for a 5-inch width ATS screen that requires a minimum of 175 gph. This is Day 1 of a brand-new ATS system, so I won't expect algae to grow for a little while.

Question: I read that cellophane can be draped over the screen-bar, to reduce splashing and stray water. So I used this method, which also quiets the water. Is this an appropriate method that will not compromise algae growth on the screen? I sure hope that is right; the light will shine through the cellophane and still cause the photosynthesis. I have used 3 layers of cellophane. Take a look at these pictures, and tell me if it looks like it will work. The system is a 14-gallon Biocube, using a 5" x 5" ATS Screen. The screen is actually longer than 5", but it is only scuffed up in a 5" x 5" area on one side of the screen. The extra length is used to allow the water to flow all the way to the water line of the sump, to reduce dripping and splashing noise. Is this acceptable? I read that it was okay to do this. If this is going to be a problem, please let me know.

Here are 4 pictures on Day 1 of the ATS, one showing the current state of the algae in my tank, the others depicting the whole set up and the ATS. Thanks for all your advice, insights, critiques, and support.

 

[_shorty_]

My ATS screen is now working fine and not overflowing with turbulent, splashing flow, after I reduced the flow from 600 gph to 180 gph for a 5-inch width ATS screen that requires a minimum of 175 gph. This is Day 1 of a brand-new ATS system, so I won't expect algae to grow for a little while.

Question: I read that cellophane can be draped over the screen-bar, to reduce splashing and stray water. So I used this method, which also quiets the water. Is this an appropriate method that will not compromise algae growth on the screen? I sure hope that is right; the light will shine through the cellophane and still cause the photosynthesis. I have used 3 layers of cellophane. Take a look at these pictures, and tell me if it looks like it will work. The system is a 14-gallon Biocube, using a 5" x 5" ATS Screen. The screen is actually longer than 5", but it is only scuffed up in a 5" x 5" area on one side of the screen. The extra length is used to allow the water to flow all the way to the water line of the sump, to reduce dripping and splashing noise. Is this acceptable? I read that it was okay to do this. If this is going to be a problem, please let me know.

Here are 4 pictures on Day 1 of the ATS, one showing the current state of the algae in my tank, the others depicting the whole set up and the ATS. Thanks for all your advice, insights, critiques, and support.

I can't see your pics from here, they get blocked. But I don't know if people use plastic to cover the whole screen? .. maybe some do, and hopefully they'll chime in if so.

In my experience, once growth occurs, there is a potential for algae to grow at the slot especially on your rings or zip-ties, and cause what I call 'the squirts' - which are small 'pee' streams that can shoot straight (almost perpendicularly) out from the screen. Very annoying, and potentially dangerous.

To combat this, I have used cheap plastic (walmart bag) material I cut into a rectangle and draped over just the upper-most section of the scrubber which hung down about an inch or so onto each side of the screen. It was a cheap and easy way to help reduce growth on the slot itself, and contain those 'squirts'. I don't know that I'd cover the whole screen unless necessary, but cellophane is clear and probably doesn't block much light. Might get to be a pain when you clean the screen, as I imagine it might want to bunch up and stick to itself, but you could always try it and see how it goes. I also recommend keeping an old toothbrush handy for this as well.

as far as oversizing screen, you should be fine, IMO. The guidlines are just that: guidelines. I've not experienced too many negatives at slightly oversizing my screens. If you compare to the original specs - majority of screen sizes were WAY oversized based on system volume, instead of feeding amounts. They still grew algae that was easily exported. I believe the newer specs are more ideal for further optimizing your scrubbers efficiency vs space and lighting requirements. I very much doubt an extra inch (even if roughed up) is going to make much of a noticable difference for you.

Good luck. Keep us posted!

 

[nanomania]

kool.....

 

[SkyReef]

In my experience, once growth occurs, there is a potential for algae to grow at the slot especially on your rings or zip-ties, and cause what I call 'the squirts' - which are small 'pee' streams that can shoot straight (almost perpendicularly) out from the screen. Very annoying, and potentially dangerous....

I don't know that I'd cover the whole screen unless necessary, but cellophane is clear and probably doesn't block much light. Might get to be a pain when you clean the screen, as I imagine it might want to bunch up and stick to itself, but you could always try it and see how it goes. I also recommend keeping an old toothbrush handy for this as well.

Hi, Shorty. Thank you for your thoughtful response. You raise a good point, and this confirms for me that I am going to scrap the cellophane long before the algae grows to such an extent, in favor of using an acrylic box with a hole in the bottom or two glass acrylic panels, to block the spray.

As far as oversizing screen, you should be fine, IMO. The guidlines are just that: guidelines. I've not experienced too many negatives at slightly oversizing my screens. If you compare to the original specs - majority of screen sizes were WAY oversized based on system volume, instead of feeding amounts. They still grew algae that was easily exported. I believe the newer specs are more ideal for further optimizing your scrubbers efficiency vs space and lighting requirements. I very much doubt an extra inch (even if roughed up) is going to make much of a noticable difference for you.

Good luck. Keep us posted!

I failed to communicate clearly: the "oversized" aspect of the screen is not scuffed up--and algae won't grow there; only 5" x 5" of the screen is scuffed up for purposes of algae adherence. My understanding was that such non-scuffed-up areas do not "count" toward measuring a screen area for ATS growth. Does that seem correct to everyone? Thanks.

 

[SantaMonica]

I have 23w bulbs. It seems like I need to find smaller watt bulbs? Is that right? Where can I get such small wattage in a bulb, 6 watts at 2700k? The lowest wattage that Home Depot sells is 12 watt and 13 watt CFL bulbs at 2700k. Would it simply be easier to use a 23w bulb against a 24 sq. inch screen on one side, rather than half the wattage on two sides of a 12 sq. inch screen?

Many places sell smaller bulbs. Seeing your setup now, a small bulb hanging from each side of the screen would work. Then you can size the screen properly, and move the bulbs closer to reduce wasted light.

The way it is set up now it will only grow a light thin brown film.

 

[SkyReef]

Many places sell smaller bulbs. Seeing your setup now, a small bulb hanging from each side of the screen would work. Then you can size the screen properly, and move the bulbs closer to reduce wasted light.

The way it is set up now it will only grow a light thin brown film.

Thanks, SantaMonica. Please explain your response, "Then you can size your screen properly." What is wrong with the sizing of the screen? Doesn't the math work out? 1-cube-per-day feeding means 12 square inches per side of a two-sided screen, or 24 square inches if using only one side. Here, I am using only one side of the screen and complying with that requirement: I have a 25-square-inch area that is scuffed up for the growing of algae. The margins outside that area are not scuffed up, and do not count toward the growing area. Is that right?

Also, what is wrong with the distance of the light from the screen? It is about 4 inches from the screen, as the recommendations suggest. Am I missing something here?

Please advise.

Thanks.

 

[SkyReef]

On SantaMonica's suggestion that I add a second side of lighting, such that both sides of the ATS Screen are lit. I scuffed up the reverse side of the screen. I now am running a double-sided ATS screen. However, the overall area will need to be reduced soon: it is 50 square inches (5" x 5" double-sided), rather than 24 square inches called for here (i.e. for the 1-cube-per-day scheme). Correspondingly, I cut the wattage of the light in half, by swapping out the 27-watt, CFL bulb @2700K for two 13-watt CFL bulbs @ 2700K. Please note that this constitutes the high-intensity light plan, where I run the lights only 9 hours per day.

Now my only headscratch is that SantaMonica suggested that I move the bulbs closer to the screen. I thought that the optimal distance of the bulbs to the screen was ~4 inches. So, if SantaMonica wanted the bulbs closer than that, then doing so would violate the ~4-inch-distance rule. I suspect that SantaMonica meant that a weaker-intensity, 13-watt CFL bulb could be placed closer to the ATS screen than a higher-intensity, 27-watt CFL bulb. On this hunch, I moved the 13-watt CFL bulbs closer to the ATS screen. They are now positioned ~2.5 inches away from the ATS screen. Is that too close for a 13-watt CFL bulb, or is that okay?

I have two pictures here: (1) with the bulbs positioned at ~4 inches away from the ATS screen; and (2) with the bulbs ~2.5 inches away from the ATS screen. Which is optimal? If the bulbs are ~2.5 inches from the ATS screen, will I encounter a "burn-out" spot on the screen, due to the intensity of the bulb at such a close range?

Note that the pictures also depict another change here: I swapped out the cellophane and replaced it with two acrylic splash-panels. It should work.

Picture 1: Light bulbs @ ~4 inches away from the ATS Screen:

Picture 2: Light bulbs @~ 2.5 inches away from the ATS Screen.

Thanks for your advice.

 

[_shorty_]

^^
Just comes from experience.. Typically, the lower the wattage, the closer you can put it to the screen. Ultimately, as close as you can get without creating hotspots is your goal. I would start with higher/longer photoperiod, personally. And start closer then move further away if/as needed, IMO.

I failed to communicate clearly: the "oversized" aspect of the screen is not scuffed up--and algae won't grow there; only 5" x 5" of the screen is scuffed up for purposes of algae adherence. My understanding was that such non-scuffed-up areas do not "count" toward measuring a screen area for ATS growth. Does that seem correct to everyone? Thanks.

sorry - you communicated well. I understood, but was just trying to bring home my point of over sizing. You will most likely still see growth on the smooth part of the screen, just probably more slimy stuff vs GHA. Should be fine though, IMO.

 

[SkyReef]

sorry - you communicated well. I understood, but was just trying to bring home my point of over sizing. You will most likely still see growth on the smooth part of the screen, just probably more slimy stuff vs GHA. Should be fine though, IMO.

Thanks, Shorty. Sounds, good. On the whole topic of oversized screens: I am now using both sides of the screen that measures 5" x 5". That means 50 square inches overall. Would you swap out the screen right now for a 5" x 3" screen or wait a while. If I change it out now, I can get the right-sized screen in there early. If I change it out later, I might get a "boost" from the double-sized screen, given that I have a lot of nuisance algae to get rid of in the tank. What do you think? Thanks.

 

[_shorty_]

Thanks, Shorty. Sounds, good. On the whole topic of oversized screens: I am now using both sides of the screen that measures 5" x 5". That means 50 square inches overall. Would you swap out the screen right now for a 5" x 3" screen or wait a while. If I change it out now, I can get the right-sized screen in there early. If I change it out later, I might get a "boost" from the double-sized screen, given that I have a lot of nuisance algae to get rid of in the tank. What do you think? Thanks.

I guess worst case, if you decided you need a smaller screen later, you can cut your already established screen down, since they take a while to 'mature'. I'd choose that along with making a new slotted pipe over using an entirely new piece of screen.

 

[SkyReef]

I guess worst case, if you decided you need a smaller screen later, you can cut your already established screen down, since they take a while to 'mature'. I'd choose that along with making a new slotted pipe over using an entirely new piece of screen.

Thanks, Shorty. I wouldn't need to make a new slotted pipe, if I go with 5" x 3"; the width of the slot is established at 5". Hence, using your method of cutting the screen size down later, I could simply snip the bottom of the already-existing screen, down from 5" x 5" to 5" x 3". In doing so, I would reduce the total area (counting both sides) from 50 square inches to 30 square inches. Although the sizing called for is 24 square inches (counting both sides), not 30 square inches, I am hoping that 6 additional square inches (counting both sides) won't hurt the algae growth. What do you think? Thanks.

 

[SkyReef]

You all talked me into it: I just snipped the screen. It is now 5" x 3" in the scuffed up area, with about 1.5 inches screen margin up top near the slot, to prevent algae growth in the slot area. However, now my sump is loud with the sound of falling water. I'll have to figure out a way to break the fall of the water, to reduce the splashing decibels.

In the meantime, here are some shots of the ATS setup now. Thanks everyone for their help.

 

[_shorty_]

In the past, I just extended non roughed up screen to the water surface by sewing it on with fishing line. You might be able to drill holes in a piece of acrylic and do the same thing if your worried about screen size being too large. Don't know if that would have enough friction for the water or not.

 

[BCool]

What is the consensus on ATS with BB systems? Will it work ok? Would there be a benefit to a SSB?

I have a 50g and am doing a overflow screen. I will start with 24sq inch of screen. Would 36w of LED in the red and blue spectrum 3" away be too much light? Seems a little overkill. How about 12w would that be better? How much flow for that size screen? Thanks in advance for the help.