[2012 updates coming soon]
ALGAE SCRUBBER FAQ (August 2010)
Scrubber Quick Guideline
Scrubber Advanced Topics
Scrubber Quick Guideline:
0.5 actual (not equivalent) fluorescent watts per gallon MINIMUM [0.13 watts per liter].
1.0 actual (not equivalent) fluorescent watts per gallon for HIGH filtering [0.26 watts per liter].
1.0 square inches of screen per gallon, with bulbs on BOTH sides (10 x 10 = 100 square inches = 100 gal)
[1.64 square cm per liter]
2.0 square inches of screen per gallon, if vertical but lit on just ONE side. [3.28 square cm per liter]
4.0 square inches of screen per gallon, if HORIZONTAL [6.56 square cm per liter].
1.5 actual (not equivalent) fluorescent watts per gallon if HORIZONTAL [0.4 watts per liter].
18 hours of lights ON, and 6 hours of lights OFF, each day.
Flow is 24 hours, and is at least 35 gph per inch of width of screen, EVEN IF one sided [60 lph per cm].
Very rough screen made of roughed-up-like-a-cactus plastic canvas.
Clean algae off of screen every SEVEN (7) days NO MATTER WHAT YOU THINK.
Q: Who owns AlgaeScrubber.Net?
A: His name is Tom Worley. He is in the U.K.
Q: Who is SantaMonica?
A: He is a reef tank owner in Santa Monica, California, USA. He is an electrical engineer by schooling, but currently works in promotion and marketing. A fish tank was originally suggested to him by one of his interns in his office, as something that would fill some space in a hallway. He hired a maintenance guy to do everything, and this guy killed everything. A second guy was hired, who killed everything again. So finally SantaMonica started reading the many forums, and decided that an algae scrubber would work great to help solve these problems. He posted his plans and info for how to build them, and thousands of people did. This FAQ is a results of what these people found.
Q: What are algae scrubbers?
A: Algae scrubbers are not brushes! Scrubbers are devices which use light and flowing water to remove the "bad" things (nutrients) from aquarium water, while leaving the "good" things (food, nutrition) in. Unlike the scrapers/scrubbers that you use to clean your glass, an algae scrubber does not physically clean anything. Instead, the "scrubbing" is when the "dirty" water passes through an algae scrubber, and then the "clean" water comes out. The water is thus "scrubbed" clean of nutrients (nutrients are “bad”, but nutrition is good).
Q: What are these scrubbers called?
A: They are called Scrubbers, Algae Turf Scrubbers (ATS), Algae Scrubbers, Algae Filters, Turf Scrubbers, Turf Filters, and Turf Algae Filters. They are all the same thing.
Q: Do I need one?
A: If you have nuisance algae growing in your tank, then an algae scrubber will remove it.
Q: Will a scrubber cause more algae to start growing in my display?
A: No. A scrubber will only remove algae from your display.
Q: How long does it take to get results?
A: Typically, your nitrate, phosphate and nuisance algae will start reducing after you have cleaned off a full screen of algae three times. However, even if you clean the screen properly (weekly), it may take a few weeks for the screen to become completely full for the first time. On average, most people solve their nitrate, phosphate and nuisance algae problems within eight weeks, and some people who have very strong lights (within 4" (10cm) of the screen) do so within four weeks. Strong lights, good flow, a VERY rough screen, and weekly cleanings are the keys.
Q: How big of a scrubber do I need?
A: Start with one square inch (6.25 square cm) of screen, with a light on both sides, for every U.S. gallon (3.8 liters) of water in your display tank. Thus, a 100 gallon display tank would need a screen 10 inches by 10 inches (100 square inches), with a light on both sides. If you can only put a light on one side, then you need to double the screen area, and also double the lighting on the one side. You don't need to include the volume of the sump, unless it also has livestock in it that you feed.
Q: Can I build a small scrubber just to see if it works, before I spend the time to make a properly-sized one?
A: The only thing a “too small” scrubber will show you is that it will grow algae. It will not show you that it can filter, because it will probably only grow dark algae, due to the scrubber not big enough to get the nutrients down so that it can grow green algae. In other words, filtering is not linear: A scrubber half the size does not do half the filtering; it does much much less filtering. That’s the reason for the recommended sizes: They are the sizes where the filtering really starts to happen. So no, you should not start with a too-small one.
Q: Will a scrubber harm my corals?
A: No. Matter of fact, corals grow best with lots of food particles (nutrition) in the water, and corals also like low levels of nitrate and phosphate (nutrients). That's exactly what scrubbers provide. This applies especially to SPS corals.
Q: Will a scrubber work in freshwater?
A: Absolutely. Same benefits, similar to plants, but in a more compact space. Scrubbers are not for "planted-only" tanks, however, because the scrubber would compete with the plants for CO2.
Q: Are the scrubber requirements any different for a fresh water tank?
A: Since you don’t have to worry about coral growth, and also since you don’t need to grow coralline like somebody with a salt water fish-only/live-rock tank might want to do, you do not need to be concerned about phosphate. Your only concern is ammonia, nitrite and nitrate. Therefore you can have, or add, extra phosphate in order to keep the ammonia, nitrite and nitrate low. Algae needs both phosphorus and nitrogen to grow, but if there is “zero” phosphate in your tank, then the algae in the scrubber won’t grow enough to remove the nitrogen (which is found in the ammonia, nitrite and nitrate). 1.0ppm of phosphate should make sure that there is more than enough, so that the scrubber has all the phosphate it needs, and can therefore work on removing the ammonia, nitrite and nitrate. An easy way to add phosphate is to get some Mono Potassium Phosphate (one source is AquariumFertilizer.com) and dissolve a spoonful of it into a cup of FW. Add a little of the water to your tank, and test for phosphate again. Repeat until the level is 1.0ppm phosphate.
Q: I've heard that scrubbers will cause your water to turn yellow.
A: Not if cleaned in your sink. Yellowing is caused by cleaning the screen while it's still in your system (the broken algae drains into your water). Cleaning weekly, in your sink with tap water, solves the yellowing that occurred for 20 years in previous scrubbers.
Q: Are scrubbers noisy?
A: Not when built properly. The screen should go into the sump water slightly, and the water should flow smoothly down the screen, with no spraying, splashing or noise. Your pumps should be the only thing you hear.
Q: Do they smell?
A: When running, they do not smell at all. This is because they always have water flowing over them. When cleaning them in your sink, there is an "ocean" smell. Nothing as bad as cleaning a skimmer though.
Q: I'm currently building my tank. Should I wait to install my scrubber?
A: No. The screen won't grow a lot, however, until you actually start feeding.
Q: I'm still designing my system. What other filtering devices besides a scrubber should I get?
A: Since you don't have filters set up yet, why not start with just a scrubber, and then monitor your nitrates and phosphates weekly as you add livestock. If you reach a point where your scrubber can no longer keep nitrate and phosphate at undetectable levels, you can then decide to either build a larger scrubber (or improve your current one), or buy other filtering devices. A powerful enough scrubber, however, can handle any size tank/fish/coral load. Algae is 90 percent of the real ocean, and does all the filtering and feeding for it.
Q: Are water changes still needed if I use a scrubber?
A: If the purpose of the water change is to reduce nitrate or phosphate, or to help reduce nuisance algae in the display, then no. If the purpose of the water change is for anything else, like removing medications, then yes.
Q: Where can I buy a scrubber?
A: A 100 square inch model is now available on the AlgaeScrubber.Net site.
Q: Can someone build one for me?
A: Any acrylic shop should be able to. There is also a list of willing builders here:
Q: What's the most important thing that I need to pay attention to when building my scrubber?
A: The screen. It needs to be ROUGH.
Q: Do I need to "seed" my screen with algae to get it to grow?
A: No. All screens will grow by themselves. Seeding (rubbing algae into the screen to get it started faster) is no longer recommended because is just does not speed things up enough, and it just puts extra waste into the water. If you want your screen to grow faster, then make it rougher by scraping a hole-saw (not in a drill) across the plastic canvas. The screen should feel like a cactus, and be too rough to rub on your face. The rougher it is, the faster algae will grow on it, and the longer the algae will stick to it.
Q: How do you clean a scrubber screen?
A: You clean it every 7 days, by removing the screen from the scrubber, taking it to your sink, and running tap water over it while removing the algae. Don't remove all the algae, however, because you want it to grow back quickly, and also because you need some algae to continue to do the filtering. So leave a small layer of algae on the screen. The rougher your screen is, the more algae will remain, and thus the faster the filtering will start again. If you have two separate screens, then you can clean one completely down to the plastic, since the other one continues the filtering. Also, if your screen is two layers (like a sandwich), you can also clean down to the plastic, since algae will remain between the two layers.
Q: How often do you clean it?
A: Once a week (7 days), NO MATTER WHAT. This is probably the biggest hassle with scrubbers, and when it is not followed, it's THE biggest reason why a scrubber is not working as good as it should. When the algae gets too thick on the screen, it blocks the light from getting to the bottom layers. Thus the bottom layers die, and they put nitrate and phosphate and cloudiness into the water. Weekly cleaning eliminates this. If your screen is smaller than it should be, or if your nutrients are very high in your tank, your screen might fill up and need cleaning in just a few days. This is ESPECIALLY true if the screen is growing dark, oil-like algae. This type of algae will never get thick because it blocks out all the light, so it must be cleaned as soon as it grows. After the nutrients in your water come down, the dark algae will grow less, and the green algae will grow more (dark algae is caused by very high nutrients.)
Q: I have a fish-only tank with large fish, and I don't care about small food particles floating around in the water. Do I need a scrubber?
A: Maybe not. If you don't mind cleaning the nuisance algae off the glass (which is caused by Inorganic Nitrate and Inorganic Phosphate in the water), then a skimmer may be fine. But if you are trying to reduce nuisance algae (and glass cleaning) then you'll need a scrubber in addition to a skimmer, because a scrubber removes the Inorganic Nitrate and Inorganic Phosphate (which is what algae feeds on).
Q: I've heard that going "skimmerless" is only for experienced aquarists.
A: That was correct before August 2008. But it is now known how to easily build and use a scrubber to do all your filtering for you (just like algae does ALL the filtering and feeding in the ocean). It is cheap, easy, and best of all there is NO possible way for something to "go wrong" with a scrubber which would cause it to kill your whole tank (skimmers, however, can overflow the cup and kill everything because of the ammonia build up). So scrubbers actually are now the entry level (beginner friendly, and cheap) way to start out.
Q: Are scrubbers dangerous, since they have electricity and water so close together?
A: They are as safe as you build them to be. Think about aquarium pumps, which have the power cord actually going in the water; since they are built for it, they are safe. Some recommended safety tips for building and using scrubbers are: Use GFCI power outlets; Use aquarium-safe silicon on all electrical connections; seal the bulbs into the sockets, and cut them out with a razor blade when you need to replace them; turn off the scrubber lights when cleaning the screen (if you must reach into a scrubber while the lights are on, use only one hand, and keep the other hand in your pocket); ventilate sump areas that are enclosed; identify what will happen if water sprays from the pipe (and use a cover if needed).
Q: Why have scrubbers caused so much anger by so many people?
A: These people are angry because:
1. They are employed by, or they are a relative/friend/spouse of someone who is employed by, a manufacturer/distributor/retailer/installer of skimmer/filtration/waterchange/additive products. There are over 3,000 stores in the U.S. alone that sell these products, with several people working at each one. That's a lot of people to post anti-scrubber comments online. And they are paid to do it.
2. They have a lot of money invested in their skimmer and other filtration equipment. So they feel ripped off to find that a cheaper piece of equipment can do a better job of removing nutrients. It makes them look unprepared.
3. They had aquariums in the 1980's, 1990's, or early 2000’s, when scrubbers were built and operated incorrectly. Scrubbers back then were noisy and caused yellowing and clouding. Scrubbers today don't. But these people have not used a modern (after August 2008) scrubber, so they think all scrubbers still operate the same.
4. They don't understand how scrubbers work, and they are not going to learn. They think that skimmers remove Ammonia, Nitrite, Inorganic Nitrate, Inorganic Phosphate (i.e., all the bad stuff). But skimmers don't do this. Not even a little. Scrubbers do.
5. Since they already have a setup that works properly, they have no reason to expend the time and energy to change. This is understandable.
Q: What is the best type of scrubber to build?
A: For most new aquarists, simple and cheap scrubbers are best. Simple configurations are just a screen hanging in a sump. For intermediate aquarists, compact size and better performance might be wanted. These configurations might be custom built acrylic units, with very bright lighting. For advanced aquarists, compactness is usually not a concern, but strong performance, and redundancy of lighting and flow, is. So a dual or triple screen, dual-pump, multiple-light configuration would be best.
Q: Where should I place the scrubber in my system?
A: Theoretically, the "best" for a reef tank is to have the scrubber above the display so that all the pods can drain into the display unharmed. But if the goal is just to remove nitrate, phosphate and nuisance algae, then it doesn't matter where you put it.
Q: Besides the designs like the screen-in-the-sump, the acrylic box, and the top-of-the-nano-tank, are there any other options for special situations?
A: Certainly: Circular, horizontal, trough, dual-screens, hang-on-wall, recirculating, display-light powered, and overflow feed, not to mention solar powered.
Q: Is a vertical or horizontal screen better?
A: Vertical is better. It is proven, and it is the smallest and most powerful for a given amount of space, flow, and lighting. Horizontal is OK if you want to experiment, but if you absolutely must have results, go vertical. The biggest operational problem with horizontal is that as algae builds up on the screen, it blocks flow to areas downstream from it. This is because the water is not flowing very fast, and it cannot "jump" up and over the new growth. So the more algae, the more blockage, and thus it is self-limiting unless you have a LOT of flow. With a vertical, however, the flow is rapid and goes right over new growth. This is the reason that a horizontal needs 4X the screen area, so it can make up for less performance.
Q: What advantages are there to wide screens? If a screen is narrow, but taller, and has the same area, isn’t it the same?
A: No. The big difference is in the amount of water processed; A screen twice as wide will flow twice as much water, and this makes a big difference in how fast it can eat the nutrients out of the water. Also, if part of the slot gets blocked by something, a wider screen will not be affected as much as a narrow screen.
Q: What are the recommendations for a screen that is horizontal?
A: People who have had success with horizontal designs have done so by having four times (4X) the screen size, and 1.5 fluorescent watts (not equivalent watts) per gallon. For example, a 100 gallon tank (380 liters) would need 400 square inches (2500 square cm) of screen, and 150 real watts of light, to be really effective.
Q: What kind of light do I need?
A: Experience has shown that at least a 23 Watt Compact Fluorescent (CFL) bulb, of the 2700K or 3000K (“warm” or “soft”) color, works best. One on each side of the screen, about 4" from the screen, and pointed to the middle of the screen. And note that 23W is "at least", unless it's for a nano. These CFL lights have also shown to only last about three months before their power drops off, even though they "look" fine. T5HO bulbs have also shown tremendous scrubber growth, although they are more difficult to design and build; their spread of light from side to side is superior to CFL bulbs. There is an upper limit to CFL bulb size; CFL bulbs in the 45 watt range are at the top, whereas anything higher than that will tend to “cook” the screen in one spot. If you must have more than 45 watts per side, use two smaller bulbs instead. The lighting just needs to be spread out more evenly, and not so concentrated in one spot. If you use CFL bulbs and they are not floodlights (which have built-in reflectors), be sure to get "CFL reflectors" so you can reflect the light to the screen.
Q: What if I can't fit a light on both sides of the screen?
A: Then double the screen size, and double the lights on the one side. Doubling the screen size without doubling the lighting, however, does no good.
Q: I can’t find the “K” numbers on the bulbs I want to buy; Can I use "soft" or "warm" bulbs?
A: Yes, the “soft or “warm” bulbs, which are the most popular types for the typical home, are about 2700 or 3000K and they work the best. Even “full spectrum” or “daylight” bulbs are OK. The ones which don’t work the best are “cool” bulbs. But they still work.
Q: Can I use LEDs for lighting the screen?
A: LEDs are still being experimented with for use on algae (which is different from using LEDs for a display.) Thus they are not recommended if you absolutely want results. If, however, results are not as important as "experimenting", then by all means try LEDs, but make sure they are as powerful as possible. A few watts here and there will not be enough. You want "reds" (670nm) and "blues" (420nm), in the high-power variety. Several horticulture and hydroponics sites sell ready-to-use LED panels and strips, which may work. You'll want as much power for the LEDs as you would for the CFL bulbs, i.e., 20 to 50 watts per side.
Q: Can I use solar power on the screen?
A: Yes, if you have many days of sun throughout the year. The screen will, in effect, be one-sided, so you'll need 2X the size (and if it’s horizontal, you’ll need 4X). It might be a good idea to still have a regular secondary or portable scrubber inside your house, in case of long lasting storms or winter days. You may also consider using a reflector (like aluminum or mylar) on the backside of the solar scrubber, and using lights on it for nights and/or backup.
Q: Are halides too strong for a scrubber screen?
A: They are not too strong, but they are very hot. So it's currently advisable to not use halides. Scrubbers do not need the deep penetration of light into water that displays need; scrubbers instead need light that is spread out evenly across the screen.
Q: How long do I wait before replacing the bulbs?
A: CFL bulbs should be replaced every 3 months. T5HO/PC bulbs every 3 to 6 months. Do NOT wait longer just because "they still look fine". You'll see, after you replace them, how dim they really were compared to the new ones. Leaving old bulbs in a scrubber can completely stop it from working.
Q: How near do the lights need to be to the screen?
A: CFL bulbs should be within 4 inches (10cm) from the middle of the screen. If you cannot get the light nearer than 6 inches (15cm), then do some reconfiguration. Don't build a scrubber at all if you can't get the light to within 6 inches (15cm). T5HO bulbs can be within 1 inch (2.5 cm) of the screen, but 2 inches is OK. Algae needs LIGHT POWER to grow.
Q: What's the best wattage/power bulb to use?
A: Generally, up to 45 watt CFL bulbs. The more powerful the light, the faster your nitrate, phosphate, and nuisance algae will be reduced, and the lower they will stay. The bare minimum for any setup is a 23W CFL Floodlight, 2700K or 3000K. A maximum might be a 45 watt bulb, but it’s better to have multiple smaller bulbs in order to reach your recommended total wattage. The ultimate are T5HO bulbs, which spread the light out so that the most light-power can be placed near the algae, without "burning" it in one spot like a CFL.
Q: I have some extra lights that I was using for my display; can I use those?
A: Only if they are 6500K or less. 10K is problematic. 14K and 20K will not work at all. And the power on each bulb still needs to be at least 23W, on each side of the screen.
Q: What's the best bulb color/spectrum?
A: The best would seem to be the "plant grow" spectrum. These bulbs looks "pink", and don't seem bright at all. But 2700K and 3000K seem to grow even better. No special testing has been done for this, however.
Q: How long should I leave the lights on?
A: 18 hours. Never run the lights 24/7, because the algae will "burn" and stop growing near the light. Algae needs rest. Amazingly, algae does most of it’s filtering in the dark; it just grows bigger in the light.
Q: I see many times that people try a certain bulb, and then they are told it's not the right one. What bulbs should I not use?
A: Don't use incandescent, blue or green "plant lights", desk lamps, reading lights, heat lamps, halogens, black lights, colored lights, actinics, bug lights, or fog lights. Do use CFL floodlights or T5HO bulbs, in 2700K, 3000K, or "grow" (pink) spectrums.
Q: If my tank and scrubber are large, then how do I know how much wattage to have on each side of the screen?
A: The basic goal is to have 1.0 watt of light for every gallon (3.8 liters) in your system for high filtering. And the basic minimum is to have 0.5 watts per gallon. So if your tank is 500 gallons, your goal would be 500 watts (total of all bulbs) of CFL or T5HO on your scrubber, and the minimum would be 250 watts.
Q: How much flow do I need on the screen?
A: At least 35 U.S. gallons per hour (gph) (133 lph) for every inch (2.5cm) of width of the screen. Thus a screen one inch wide would need at least 35 gph, and a screen two inches wide would need at least 70 gph, etc. More is even better. Less flow means less performance, and parts of the screen may go dry. And if you are making a horizontal screen, you then want ALL the flow on the one (top) side. This is because fast flow is critical, and horizontal screens do not have fast flow. So you make up for this by putting all the flow from a two-sided screen onto the one top side of a one-sided screen. And in all screens, flow will be limited by the roughness of the screen, because a smooth screen will let go of algae sooner than a rough screen will.
Q: What's the best material to make the screen out of?
A: The overall best material is "plastic canvas", which can be found at any craft/sewing store, and online at hundreds of places. It's cheap, strong, and does not wear out. However it's smooth and it's made out of non-stick plastic, so to make it work the best, you need to rough it up using a hole-saw in your hand (not in a drill) so that it feels like a cactus. The rougher it is, the quicker the algae will grow, and the thicker it will grow without falling off, and thus the less nitrate, phosphate, and nuisance algae you will have in your display. Just remember that the more algae that can grow/stick on the screen, the less algae you will have in your tank.
Q: Can I use window screen?
A: No. That type of screen sometimes has chemicals to reduce mildew. Plus, it's too flimsy, and it cuts/breaks too easily. And sometimes it's metal.
Q: Can’t I just rough up a sheet of acrylic?
A: No. It’s not nearly rough enough.
Q: I saw some people using clear tubing for the pipe; won't this grow algae in the tube?
A: Yes, and the algae will block the slot. Don't use clear.
Q: What can I do to get the best results from my scrubber?
A: When building, use the most wattage that you can, and put the bulbs within 4 inches (10 cm) of the of the screen. Preferably, use T5HO bulbs within 2 inches of the screen. When operating, clean the screen weekly, no matter what, using tap water in your sink. Clean sooner if the algae is dark brown or black. Replace the bulbs every 3 months, and watch the pump to see if it starts reducing flow. Make your screen VERY rough. And make the flow rapid across all parts of the screen.
Q: I heard that you have to watch out for "oil slicks" on your screen.
A: An "oil slick", or very dark or black algae, usually happens when a scrubber is first set up on a tank with very high nutrients. This type of algae does not get thick, and it doesn't even look like algae. The problem is when the person thinks that his screen is "just not growing yet", and he leaves the screen alone (not cleaning it) in order to "give it more time to grow". BIG MISTAKE. What actually is happening is that this particular type of algae is already fully-grown on the screen. And since it's very dark, the outer layers block ALL the light from the inner layers, even though the algae is only 1/4 inch (6mm) thick. So the inner layers die and go back into the water, adding nutrients back. So the person leaves the screen alone even longer "to give it even more time to grow", but the new outer layers once again kill the inner layers. The screen never gets "thick" like the person wants, and so the person never cleans it. Nutrient levels stay the same in the tank (and the water gets cloudy because of the dying inner layers), and the person feels that the scrubber is not working at all. The solution is to clean any and all dark/oily algae off as soon as it grows, EVEN IF it's just two days old. This will bring nutrients down, and after a few weeks of doing this, green hair algae will start to grow. At this point you can switch to normal weekly cleaning.
Q: All I seem to get on my screen is brown slime. Must I have green hair algae?
A: No. All algae takes nutrients out of the water. They are just different types of algae depending on how high your nutrients are in your water, and how strong your lights are. Continue the weekly cleanings (twice a week if the algae is dark brown or black), and eventually you will get green. If not, try a stronger light, and possibly, stronger flow. If you never get green growth, your scrubber is just not strong enough for the amount you are feeding your tank. But you may still be happy with the results. Or, your scrubber may need "kick starting", which is just helping it out by using extra lights until the scrubber starts growing green.
Q: I'm not getting good flow out of the slot in the pipe, especially when the screen fills up with algae. What can I do?
A: Add a light-shield on the pipe which keeps light from reaching the slot. Plastic opaque tape, or a piece of long plastic, works. Ideally though, you should clean the screen when the algae gets that thick.
Q: My scrubber smells. Is this normal?
A: No. It means your water flow is too low, which lets some of the algae touch the air. Increase your flow, or widen the slot. If you still can't get enough flow, make the screen shorter (with a new shorter pipe), so that the flow that you do have will really cover the whole screen.
Q: I'm getting cyano on my screen. Is this good?
A: No. It means your light is too weak or too far away. Regular algae (green, slime, brown) should be the only thing that is growing, but it can't grow if the light is too weak.