Algae Turf Scrubbers - myth or reality

Discussion in 'Equipment' started by rygh, Dec 13, 2010.

  1. rygh

    rygh Supporting Member

    There is a lot of confusing data out there on algae turf scrubbers.
    Some wrong, some right, and a lot I am not sure about.
    I have been running a turf scrubber for a couple of years, in a system
    that is mostly fish and a few softies. Not SPS!! I have also read up and studied them quite a bit.
    So I am knowledgeable, but hardly some super-expert. Although I am not sure one exists.
    I take that back. I am sure one does not exist.
    Thus, everything I say below is completely true unarguable fact - NOT. H)

    On a personal note, I was not originally planning on having many SPS corals in my new tank, but
    since joining the club, I am rethinking that, and thus also rethinking my ATS strategy.
    So this thread is as much for me as anyone else.

    ------ THE BASICS -------

    What is an Algae Turf Scrubber? (ATS)
    First off, it is named wrong. Nobody grows turf algae anymore. :)
    Basically, you have a box with a roughed up plastic screen that you pass water across,
    and you have bright lights shinning on that, where you deliberately grow hair algae, and scrape it off weekly.
    The hair algae absorbs the nitrates/ammonia/etc, and you export it by manual removal.
    It is REALLY good at removing nitrates. That is not hype or fantasy, it is true.
    A good ATS can take a 100ppm nitrate tank to 0 in less than 5 weeks.
    It also wipes out phosphates, some bad metals, and amusingly, can even keep a new tank from ever cycling.
    That part is great, but there are downsides discussed later.

    How do skimmers/ATS differ?
    An ATS works by the algae absorbing the ammonia/nitrates directly, and manual removal.
    An ATS does not remove dissolved organics or detritus.
    A skimmer works by removing dissolved organics, BEFORE they turn into ammonia, and manually removing them.
    A skimmer does not remove ammonia or nitrates.
    A huge difference.

    So who should consider a scrubber?
    The main issue boils down to how ammonia is created.
    A) In a fish-dominated tank, a lot of ammonia is created DIRECTLY by the fish. (pee-sortof)
    You end up with a lot of ammonia that a skimmer can do absolutely nothing about.
    Now anaerobic bacteria can of course convert a fair amount of nitrate to nitrogen.
    But as you near max bioload, you easily overpower the bacteria.
    So you end up with endless water changes, and chemical filtering.
    ** So, if you have a lot of fish, and just a few softies, an ATS is a fantastic solution

    B) In a coral-dominated tank, most of the ammonia is created by rotting detritus from food/etc.
    Whatever the coral does not eat eventually decomposes to ammonia.
    There is not a lot of bio activity directly creating ammonia.
    So what is the best fix - to remove those organics in the first place of course, with a skimmer.
    You remove the crud before it becomes ammonia, which means you never really have a big nitrate issue.
    ** So, if you have a low nutrient SPS dominated reef, with few fish, an ATS is pointless at best,
    and a coral killer at worst.

    C) In between - it is a tricky call.
    You have a mixture of fish/coral, and are sick of the nitrate problems requiring all those water changes.
    Do you take on the risk/setup hassle, or not?
    And remember, it is not an either/or decision.
    You can (and should) have a skimmer and do water changes, even with an ATS.

    --------------- MYTHS AND REALITIES ------

    They turn my water yellow and spread algae to my main tank.

    False. Well, they do if you have a poor design, or do not clean enough and properly.
    If set up well, they actually REDUCE the algae in the main tank, thus making your water clearer.
    Done right, they can even out-compete the other algae totally.

    They are a huge amount of maintenance.

    False. No offense, but this is really a statement on your design skills in building an ATS.
    The concept is simple - remove a screen, scrape it, put it back, once a week.
    Build it right - easy. If you have to dismantle everything to clean - hard.
    On mine, it takes maybe twice as long as cleaning the skimmer cup.
    (Yes, I plan to post a video for those skeptics)
    Now if you factor in the water change reductions, there is overall LESS maintenance.

    I have never seen an ATS on a successful SPS dominated reef tank.
    Generally true, but it does not really prove anything.
    There are some experimental ATS+SPS tanks out there, but that does not prove anything either.
    But if you think about it, IT MAKES SENSE, since ATS systems are not really best
    for SPS dominated tanks. There are better methods. People experiment, then realize that.

    They eliminate the need for water changes.
    Dream on. But they do reduce it in many cases.
    They eliminate the need for water changes specifically for nitrate reduction.
    And with nitrate problems, that could be a lot of water changes eliminated.
    But there are a lot of other benefits to water changes.
    Seems like 5% / month are common, but no real data.

    They eliminate the need for a skimmer.
    Well, kinda, but a bad idea.
    They do nothing to reduce detritus, and even create a bit of their own.
    So you end up with a bunch of crud. Which yes, does eventually turn to ammonia and off to ATS.
    Seems like that crud is a bad idea though, and likely chokes coral.

    Various chemicals produce by algae, such as phenols, skatoles and creosols, cause problems in corals.
    It is clear that algae do produce that, and it can somehow hurt SPS corals.
    It is clear that improperly running turf scrubbers can destroy reef tanks, with SPS going first.
    It is far less clear that a "PROPERLY WORKING" ATS produces these in quantities remotely enough to be a problem.
    And some guess that it may even reduce them.
    ** This is a key and pretty big discussion. I think I will defer it a few more days until I do more research. **
    So not sure if this is myth or reality.


    They can use a lot of power!

    You need upwards of 1 watt per gallon of lighting on the screen, for a whopping 18 hours / day.
    You need roughly 10 GPH of flow on the screen per tank gallon.
    That consumes a lot of electricity.
    Reduced by sharing return pump, and LED lighting. But a big concern, especially if designed wrong!

    They are a big pain to get right!

    Since they are rare, there are few off-the-shelf solutions.
    And even if there were, they need to be sized right for a given tank.
    Getting the screen the right size, the flow high enough, the lighting timing right,
    all ends up being a royal PITA!
    From my posts you can probably tell I like tinkering. And even I was frustrated.

    If done wrong, poorly maintained, or even removed too quickly, they can destroy your tank.

    There are two major failure methods:
    1) Pollution.
    You don't clean enough, or screen is too smooth, and you end up with loose/dying algae throughout the tank.
    This suffocates and kills things. (** This is what may be prompting a lot of the phenol/chemical concerns)
    2) It stops working and your tank suddenly cycles
    If it fails, or you forget to clean, or whatever, you need to remember that your
    tank is now reliant on it. Just like if you killed the beneficial bacteria, all
    of a sudden you lose filtration, and ammonia/nitrite will spike.

    They are DANGEROUS if done wrong.

    I got into it with the leader of a bit on this.
    A simple setup goes like this.
    You take a bucket, pump, some pipe, drill some holes, create a little screen-waterfall.
    Then you get some old light sockets, and a few CFL bulbs from home depot, and put those in the bucket.
    Oh, and then you put your hand in there every week to clean it.
    HELLO!! Salt-water, falling unprotected, next to high voltage, and you put your hand in.
    Maybe you are nervous, and you post saying "Is this ok?"
    You get response like : Light is too far away. Add aluminum foil reflector.
    Not : That salt water will get in the socket, and could kill you.

    ** Notice a theme here : IF DONE WRONG **
    My strong opinion is that the complexities of setup have resulted in a ton of failures,
    causing most of the anti-ATS bias.

    ------- MY PERSONAL EXPERIENCE ------

    This of course proves nothing, but hey, I wrote this, so I get to tell my story.
    As mentioned, I have a tank with quite a few fish, and a few softies.
    And .... wait for it .... I had a nitrate problem.
    I tried a remote deep sand bad. - It helped a bit for a while, then not.
    I tried an expensive denitrator coil - useless.
    I tried chemical. - Worked, kindof. And expensive, and hard to tell when to replace.
    So I tried a turf scrubber.
    First few designs failed.
    But I did get it working, and for 2 years now, Zero nitrates, Zero phosphates.
    I got sick of the power usage, and switched to LEDs. That was a pain also,
    because it turns out that algae is a bit finicky when it comes to spectrum.
    But the right mixture of warm-white and deep-red, with a bit of blue, works great.

    I even did a fun experiment recently: I turned off my skimmer, and stopped doing all water changes.
    That lasted a long time with apparently little problem.
    No measurable water chemistry issues. Nothing died. But detritus was getting thicker....
    At about the 5 month mark, things started going bad fast.
    My zoas started closing up, I lost some snails, and I started getting Cyano. (Odd combo)
    So big water changes, skimmer back on, and things are mostly back to normal. Still not perfect though.
    My theory is that the sand bed and rock were buffering things for a while, plus the detritus simply piled up way too much.
  2. ryanjiang

    ryanjiang Guest

    I am sure the ATS will work if setup correctly.

    But my point is why bother? With today's technology, an effective skimmer tuning right, run active carbon & changed monthly, properly run GFO. These things alone should keep the nutrient in acceptable range (even for SPS) without massive water change.

    If you still want to further eliminate nutrient (which might not be a good thing), run a refugium, or go to bacteria driven system.

    For my system, effective skimming & daily dose 2 drops of MB7 (bacteria source by brightwell) alone keep the N at 5 P at 0.03, I only do monthly 10 percent water change. I do run GAC in filter bag, but no refugium, no GFO.

    No algae issue in my system but Cayno is hard to beat with my sugar grain sand bed.
  3. Qwiv

    Qwiv Guest

    There are some flaws in your logic:

    A) In a fish-dominated tank, a lot of ammonia is created DIRECTLY by the fish. (pee-sortof)
    You end up with a lot of ammonia that a skimmer can do absolutely nothing about.
    Now anaerobic bacteria can of course convert a fair amount of nitrate to nitrogen.
    But as you near max bioload, you easily overpower the bacteria.
    So you end up with endless water changes, and chemical filtering.
    ** So, if you have a lot of fish, and just a few softies, an ATS is a fantastic solution

    FALSE: In a fish and softy dominated tank, you typically worry much less about nitrate and liverock, sand, wet/dry can easily process ammonia to nitrate. Getting nitrite to nitrogen is only important as you move into corals, especially SPS. (generally). Second, you can still overfeed a fish/softy tank and have detritus problems. Those problems have no relationship to what type of tank you are keeping.

    B) In a coral-dominated tank, most of the ammonia is created by rotting detritus from food/etc.
    Whatever the coral does not eat eventually decomposes to ammonia.
    There is not a lot of bio activity directly creating ammonia.
    So what is the best fix - to remove those organics in the first place of course, with a skimmer.
    You remove the crud before it becomes ammonia, which means you never really have a big nitrate issue.
    ** So, if you have a low nutrient SPS dominated reef, with few fish, an ATS is pointless at best,
    and a coral killer at worst.

    FALSE: Corals still create ammonia and the amount of ammonia created from rotting detritus is a function of your feeding habits and tank set-up. It has nothing to do with what is in your tank. I can literally dump food in my SPS tank because it is designed to keep food in suspension which is opposite of my old softy tank where food could hide and rot.

    On your experience, is sounds like your ATS was a failure in terms of a tank filtration system but was effective as a compliment to a skimmer and water changes, much like a refugium. Matches my experience with them when I tried some in the late 90s. I then went to a refugium, was not called that yet, as I enjoyed the benefit of having another tank full of creatures to look at. Watching an ATS is pretty boring. Watching a nice refugium is more fun than watching the corals sometimes for me. My last (2) previous tanks had a design feature kinda like a ATS design. I specifically designed my overflows to grow hair algae in screent originally meant to keep the snails/fish/shrimp out and scraped them as a nutrient export. I wasn't depending on it, it was a bonus.

    I spent a lot of time messing with ATS way back then and people are building them differently now, but it still functions the same. The facts are they will only support a certain type of tank, supplement a few others and cannot be implemented at all in many others. They have a limited place. The tank/skimmer combo is much more robust of a system and a refugium can do the work of an ATS if designed to do so. The problem with refugiums is peoples expectations. Most people add a small tank with low flow, a weak light, throw a piece of cheato in there and expect it to suck up all the nutrients and feed the tank millions of pods over night. That's not how it works. Want to grow most algea, you need light and flow. Want to grow pods, you need surface area for habitat and food. One limits the other. If you need more of both, you need a bigger refugium.

    Still nothing replaces a good water change. I don't care if you have the perfect ATS that removes 100% of all ammonia - nitrites + PO4 and releases 0 toxins to the tank, is is doing nothing to replace al the trace elements in a fresh batch of salt water. Sure, you can supplement all the trace elements as well but then you need to test for them. I'll buy you a beer if you can test for all the trace elements in the tank faster or cheaper than I can do a water change.
  4. rygh

    rygh Supporting Member

    Yes, the more hi-tech approaches do have their merit. Especially as they are getting more refined, and cheaper.
    And if I bail on an ATS setup, the plumbing is already there for a GFO/GAC/Phosban reactor.
    My concern there is scale and cost. It can potentially take a LOT of chemical filtration media for a heavy bio-load tank.
    Constant water changes are another fun hi-tech approach.
    But I may have to do the cost analysis there.

    Regarding refugiums - well, they are essentially lower performing turf scrubbers if you think about it.
    Just a different kind of much slower growing algae. So they would have to be BIG.
    A bit more fun though.
  5. ryanjiang

    ryanjiang Guest

    + 1.

    One thing I want to ask is how important role does trace element play to the look and health of corals? Seems lot of arguments here and there.

    Let assume certain trace element is critical to certain corals, then even the large/frequent water change can not solve the trace element problem, unless you do 50 - 100 percent WC and assume your Salt mix has proper concentration for that element.

    Of course WC is always a good insurance tho.
  6. rygh

    rygh Supporting Member

    I am cutting snippets out of this big reply.
    It had some great points. Especially about tiny-refugiums and water changes.
    (I did start with a refugium, which is largely why I went to an ATS. Basically a turbo-refugium)
    Just a couple of things I disagree with.

    You worry less yes- for a while - but it is only a matter of time.
    As soon as the generation of nitrate moderately exceeds the conversion to nitrogen, the nitrate level slowly and continually rises.
    Water changes become a bit more effective at higher concentrations, as do bacteria/etc, but not enough.
    So eventually it becomes a critical problem, until even damsels start to die.
    Those anaerobic bacteria are limited by regions with no oxygen plus decent nitrate levels. They simply
    cannot multiply enough to compensate.
    Of course - you can easily argue the system is simply overloaded, which would be true.

    Sure, but compared to a fish, I think it is far far less. Metabolism differences mostly. Could be wrong though.
  7. Qwiv

    Qwiv Guest

    You can design a refugium that grows macros faster than you think. You need to expand the idea of refugium besides a 10 gal tank, sand, cheato and a light. Why not have a refugium that is only 1 inch deep covered in a medium that promotes algea growth? That is almost an ats. How about a dark area with a grid of egg crate covered in sponges. I ran a cryptic refugium that was incredibly successful. I miss it actually. There are a few well known reefers who use them. Mr LE is an example. With the advent of biopellets I am going to implement it again. My thoughts that finding a sponge that consumes the specific bacteria sold to jump start the bio pellet theory would be a combo. How about a xenon refugium?

    On the build up of nitrate, you are exceeding the capacity of your tank or your husbandry is lacking. Adding an ATS is just increasing the capacity of your tanks filtration. You could also upsize your skimmer or increase water changes to get a similar result. If you have high nutrients, water changes are known to work all the time. If you remove more pollutants than you add, you will have a positive effect. Also, tons of small water changes are less effective than one large ones, but less stressful. doing a 50% water change will remove 50% of the nutrients, assuming nothing replenishes what you removed. Doing 10 5% water changes (even in a single day) removes way less because you are removing fresh water with each change. See here.
    How many times do you see people say they have x amount of po4 and they want to get to 10% of that. They do maybe 5 to 9 10% water changes and complain they are not making progress but would need to do 22 according to the math to get there assuming the tank concentration stayed the same.
  8. rygh

    rygh Supporting Member

    I have been going back through some of the ATS "success" stories on the net
    with a critical eye, analyzing those that have a lot of SPS.

    Here is one of the better ones BTW:

    It is rather funny. It seems that adding an ATS can eliminate one and only one other filtration device.
    Pretty much whichever one you want, but only one.
    Eliminate skimmer - use carbon and normal sizable water changes.
    Reduce water changes - use carbon and skimmer.
    No carbon- use skimmer and water changes.

    And of course, a few that do it all, in moderation.
    Smaller ATS, smaller skimmer, a bit less water changes, occasional carbon.


    A big goal on people removing the skimmer was to improve coral feeding.
    It is true that a skimmer removes what is effectively food to corals.
    And in particular, an ATS produces a lot of baby pods, ideal for coral.
    Due to algae, you get a lot of pods.
    Due to weekly cleaning in fresh water, pods stay small.
  9. ryanjiang

    ryanjiang Guest

    Looks like you are a true believer :)

    Maybe just do this:

    But why not 7X24 carbon? I believe if you run LESS amount, non-super aggressive type, change frequent, it should be no harm. You get better water clarity in turn improve the light efficiency.

    Plus cost is so low if you buy bulk & you don't have to run it in reactor, what is the point of not running it?
  10. Thales

    Thales Past President

    Nice write up. My general issues with ATS is that they are promoted as a panacea with magic powers and a fix all for everyone and everything. They aren't, but many of the ATS fans don't want to admit that. :D Most of the people I see adding them have newer tanks with algae issues and then say the ats fixed the issues which I think may be a bit of a post hoc situation, and think that most of the nutrient issues would resolve as the tank matures. I also don't understand people adding them to systems without nitrate issues. That said, these do have their place, they just aren't the magic bullet that Sanata Monica makes them out to be.

    I have a defacto ATS and I hate it. My perimeter bracing grows turf that I have to scrape. Pain in my bootie. I think having to scrape algae from a large ATS would make me crazy - I am looking to do less, not more. :D

    15% weekly water changes! Siphoning algae! Carbon monthly! That will deal with the yellowing/toxicity issues. :D With that much water changing, he could prolly ditch the ATS all together. It would be interesting to take it off line and see what happens.

    Thats generally the case with any filtration isn't it? There are plenty of tanks that run skimmerless, carbonless etc but do more water changes. Its all about exporting nutrients or reducing pollutants and there are many ways to get that accomplished.

  11. rygh

    rygh Supporting Member

    Sorry, the part about the pods/better coral feeding was
    a reiteration of the goals some people stated as to why they wanted an ATS.
    It was not meant to be stated as fact at all.

    Regarding a few of the questions:
    A certain percentage of pods should naturally fall off the screen. It is a waterfall.
    When you clean it, you rinse it in fresh water, killing the pods, so they never have a chance to grow big.
  12. GreshamH

    GreshamH Guest

    One glaring hole in your logic.... little pods don't breed
  13. rygh

    rygh Supporting Member

    I am still a true believer that an ATS is AMAZING at removing nitrates.
    Better than any other reasonable method.
    But I tend to believe it is useless for anything else, and comes with enough issues that
    you should not jump into it lightly.

    I am not sure about running carbon non-stop. Need to look into that.
    I have heard in quite a few places that it can strip valuable elements, causing long term problems.
    On the other hand, it might be the same sort of ATS like issue: If you ONLY run carbon, then you get problems.
  14. Thales

    Thales Past President

    Gotcha. That kind of misunderstanding is my main worry with discussions like this.

    I am not sure we can think that. Still not sure which pods we are talking about, but if they live in turf, the are prolly intertidal and would laugh at the power of home waterfalls. Forgetting that - what percentage? Is it a useful amount? How do we know? What corals are supposed to be eating them? Do we have evidence for any of it, or did someone just say it cause it seemed to make sense? :D

    So how are they breeding? :D
  15. rygh

    rygh Supporting Member

    First, I do want to reiterate that was not really my logic, and my main goal is
    nitrate reduction. Feeding corals by hand is fine by me.

    But I do know the supposed answer:
    The main ones in the tank breed, sending eggs / larvae everywhere.
    Those get stuck pretty easy in the algae and screen, where there are no
    predators and tons of food, so a huge percentage hatch safely,
    and grow like gangbusters for a week.
  16. Thales

    Thales Past President

    Agreed - except for the better than other reasonable methods.

    Lots of people do it.
    Thats one of those things that people say that has no/poor evidence to back it up.
  17. GreshamH

    GreshamH Guest

    Given you posted it and wrote it as yourself with no quotes, it's your logic. Use the quote feature to denote it's not you saying it ;)

    no "pod" lays eggs.
  18. rygh

    rygh Supporting Member

    Yep, pisses me off also, because I was really trying to be careful not to do that.
    I think one of the reasons people are anti-ATS is because there is so much
    overblown hype, that is simply sets off peoples BS alert.

    Well, someone could put a filter sock before and after an ATS, and check the second sock for pods with a microscope.
    Has anyone - not that I know of.
    So I am guessing the latter hypothesis is true.
  19. rygh

    rygh Supporting Member

    Well Mr Nitpicker ... :)
    They DO produce eggs, but secrete them in an eggsack on their body, where they hatch.
    So is that "laying" - maybe, maybe not.

    But the theory does hold that larvae could move from the main tank into the ATS,
    and they could grow very happily there.


    Yes, I need to be more careful of quotes and how I word things.
  20. Thales

    Thales Past President

    You bet! If you are sharing other peoples ideas, you need to be extra careful!
    Then IMO we need to be very careful about stating it as true.
    Gammarus absolutely get around in a system, they show up in filter socks all the time. The bigger issue here is the idea that larval pods feed coral - that seems pulled from the air. And, if coral are supposed to eat larval pods, but the main breeding pods are in the tank proper (and only small ones on the ATS because they are killed weekly), then I am unsure how the ATS helps the pod situation.

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