Why a DIY Algal Turf Scrubber?
For many years my reef aquarium system included a refugium. A little over a year ago, in the middle of my "Old Tank Syndrome" phosphate crisis, I took the refugium offline and replaced it with an ATS (Algal Turf Scrubber) system. The ATS was a classic "dump tray" style revolutionized and advocated by Dr. Walter Adey and sold by Inland Aquatics. The Adey design relied primarily on the growth of red turf algae and helped to reduce my nitrate and phosphate levels since its addition. That said, the dump tray style ATS had several drawbacks. For starters it was huge, measuring 30" x 12" x 18". The shuttle (dump tray) seasawing back and forth was far from silent even if the metronomic sound was not bothersome.
Algal Turf Scrubber Evolved
In recent years a new breed of highly efficient Algal Turf Scrubbers has evolved. The newer ATS systems utilize a fixed screen that hangs in a waterfall and is illuminated from both sides with LEDs. The "waterfall style" scrubbers excel at growing GHA (Green Hair Algae) and have a much smaller footprint for the same (or greater) growing area as the dump style ATS systems. By most accounts, the green hair algae grows much faster than the red turf algae and therefore provides a better nutrient export machansim in a smaller space. Being happy with the concept of an Algal Turf Scrubber, but not happy with the size or performance of my current unit, I decided to upgrade to a waterfall style ATS.
DIY Turf Scrubber Plans
My first inclination was to purchase the needed materials, including acrylic sheet stock (both black and clear) and associated fittings, LEDs, and other supplies. Algal turf scrubber plans are available from many websites and the design is rather simplistic. A respected Reef Central member, Floyd R. Turbo (Bud Carlson) recently started selling complete waterfall style ATS systems (www.turbosaquatics.com) that incorporate all of the design features I was looking for. The only problem was, that Bud was only ramped up to sell complete turn-key ATS systems and had not put together a "kit" or kit pricing yet. Luckily, he agreed to sell me an unassembled scrubber "kit" containing everything I would need to build the Turbo's Aquatics "L4" size waterfall Algal Turf Scrubber.
Turbo's Aquatics L4 ATS
Bud builds at least 3 different sizes of turf scrubbers (L2, L3, L4) and I chose the largest model, called the L4. As mentioned above, the Turbo's Aquatics L4 is a waterfall style algal turf scrubber that incorporates many (all) of the design features I was looking for. It appears that Bud has spent considerable time adapting and perfecting many aspects of the popular waterfall designs.
They key features (for me) are:
- lighting and growth efficiency
- ease of cleaning and maintenance
- noise (lack of)
- reliability and ease of operation
The L4 features an overall rough dimension of 15" x 9" x 7", including the LED heatsinks. This is easily half the size of the Adey style scrubber that the Turbo L4 Algae Scrubber is replacing!
The 13" x 4" screen is illuminated on both sides by a combination of LEDs, predominatly in the 660nm range. This is a departure from the Adey style unit that utilized (2) 12x12 screens illuminated from the top by compact fluorescent bulbs. The targeted spectrum of the LEDs is far more efficient at growing algae, producing less (zero?) light energy wasted by unusable spectrum. The end result is faster growth from a smaller screan area, using a fraction of the electricity!
The dump style skimmer was actually somewhat bothersome to clearn. The heavy acrylic tray was cumbersome to manipulate and barely fit in the laundry tub. The Turbo L4 utilizes a simplistic PVC union tha tallows removal of the entire spray bar and screen assembly. Easy to remove (and may I say very clever "split slip rings" are used to secure the screen to the spray bar. If the entire box needs to be cleaned, the LED heatsinks simply slide right out and the whole unit will easily fit in the sink.
The Adey style dump tray makes a bit of noise as it seasaws back and forth. The slight "bump" sound at the end of each tip of the tray is not bothersome, but I would prefer silence. The in-wall aquarium is part of my home theater and the equipment room is open to my office.
Lastly, there are no moving parts and the LED light source does not need regular replacement. The Adey ATS could have been retrofited to LEDs, but the single sided screens and large footprint made that an unnatractive option (at least for me). The dual-drain design compliments th safety and redundancy of my silent and fail-safe overflow system. There is no way a rogue hunk of green hair algae is going to cause this ATS to overflow! Nonetheless, I may incorporate an electrical failsafe in the form of an optical sensor and latching circuit (more later).
L4 ATS Parts Kit
Instead of boring you with packaging details, I will let the photos speak for themselves and simply say that it is a rarity to have something delivered that is packaged with so much care and neatness. Numerous layers of bubble wrap, shrink wrap and padding were used to protect the various (nearly nested) parts of the ATS kit.
As I mentioned, my initial plan was to source everything I needed and build the turf scrubber from scratch. While this is certainly possible, there are a significant number of parts needed to complete a professional looking and fully function scrubber. After unpacking the kit, it was abundandtly clear that sourcing these parts would take
- Makers LED Heatsink (2)
- Makers LED Fan (2)
- Makers LED Fan Shroud (2)
- Makers LED End Caps (4)
- Acrylic End Pieces (2)
- Acrylic Windows (2)
- Acrylic Bottom (1)
- Acrylic Top Half (2)
- Acrylic False Bottom (2)
- Acrylic Lid (1)
- Acrylic lid and bottom braces (6)
- Acrylic Spacer Jig (1)
- Pre-Slotted "Spraybar" Tube (1)
- Sample of "roughed-up" Screen (1)
- Pre-cut Algae Screen (1)
- Spare Algae Screen (1)
- Screen Holder Rings (2)
- Zip Tie Tube "gaskets" (2)
ATS Box Construction
The body of the algal turf scrubber is rather simple in design and is constructed using 7 individual pieces of cell cast acrylic (listed above) that are systematicaly solvent welded to form a water tight box. The "pins method" of construction was used for the entire project.
As I had prior significant experience working with acrylic, I started the project as soon as the package arrived from Turbos Aquatics. Being eager to get started (and against Bud's wishes) I opted to build the box before he was able to complete a step-by-step guide. Sorry Bud!
Once the basic box was solvent welded together I used a laminate trimmer to flush cut the bottom, lid and slot-pipe area. This was literaly a 5 minute job. The finished box was set aside while I wnet to work on the LEDs.
While I did not need the well written instruction, I have linked them here in hopes that they may help others working on this or similar projects. Bud did a wondeful job with photos and explanations that apply to most basic acrylic work.
Visit the image gallery that contains photographs of many of the steps in the build process.
ATS Screen and Spraybar
The scrubber screen is simply standard needlepoint canvas that is significantly "roughed up" so that the algae has a place to take root. The "roughing up" can be done in several ways, but the general consensus is that rubbing the screen with the sharp end of a hole-saw is the most efficent method. It is important to ensure that the area of the screen that fits into the spraybar (slot pipe) is left smooth. The smooth plastic surface helps to prevent algae from taking hold and clogging the slot in the pipe.
The spraybar is simply a length of PVC pipe, with a slot milled into its length. One end of hte pipe is capped and the other fitted with a union or other means of quick disconnection. The slot is slightly wider than the thickness of the plastic needlepoint canvas and allows water (pumped into the open end) to cascade over boths sides of the screen in a waterfall fashion. The slot pipe rests in cutouts fashioned into the end panels of the scrubber box.
LED and Heatsink Construction
The scrubber kit was shipped with (2) MakersLED heatsinks and the rest of the components listed above. The discrete LEDs came pre-soldered to LED stars for easier mounting and connection. I opted to tin each connection pad on the LED carrier stars (from here, simply refered to as LEDs) at the workbench before mounting them to the Makers Heatsinks. While tinning the pads and soldering the wires can be done in-place on the heatsinks, doing so can be cumbersome. The heatsink tends to wick away heat from the pad as you try to solder.
Once the pads were tinned with a nice neat glob of solder, each LED was mounted to the heatsink in its final position. A tiny dab of thermal compound is squished between each LED and the heatsink to aid in thermal conduction from the LED to the heatsink. nylon insulating washers are used to prevent the mounting screws from touching the pads on the LED carriers and creating an electrical short.
The LEDs on each heatsink are wired in series with one exception and that is for the blues which are wired in a series-parallel set to reduce the current passing through them. As the wiring and soldering were straight forward, there is not much to say. I have attached the schematic here.
For the time being the MeanWell LED drivers (120V) are resting beside the turf scrubber. They are wired to the LEDs via the waterproof automotive style connectors that Bud supplied in the kit. I will eventually build a small wall mounted project box to hold the drivers and enclose the wiring in techflex sleeving for aesthetics.
ATS System Plumbing
The ATS is fed directly from a branch of my return plumbing and drains directly into the sump via the bottom drain and a ball valve. The side drain of the scrubber unit is also plumbed to the sump. The ATS sits above the display level (it is the only convenient location). Due to the approximatley 3' drop, the drain has been rather hard to silence. If left fully open, the velocity of the water generates a significant suction and flushing action as the drain oscillates between siphon and two phase flow.
I am able to quite the drain down by adjusting the ball valve and restricting the flow but am not comfortable restricting it to the point that the side (emergency) drain is engaged, in effect creating a "Herbie overflow". Firstly, doing so does not allow for any wiggle room in the event of a clogged primary drain. Secondly, if the emergency drain is active it leaves roughly 2/3 of the growing area of the screen fully submerged in water. I have fiddled with air admittance solutions to transform the main drain into something akin to a "durso" but as with any air assisted standpipe setup, have had significant stability problems.
While doing maintenance a few weeks after the scrubber started fully producing, a clump of algae must have become disloged and plugged the "emergency drain". Upon system startup, I adjusted the main drain to a "balanced" siphon level and walked away only to hear the dreaded "waterfall outside the tank" sound a few minutes later.
I am not pinning the drain noise on Bud or the scrubber design, but rather my hasty installation and unwillingness to fully re-plumb the scrubber to overcome the problem. I also assume that most users will place the scrubber at or near sump level, thus eliminating most of the drain issues I have encountered.
I can not thank Bud Carlson enough for putting this kit together and allowing me to purchase it. The parts were well designed and precision cut with superb attention to detail. The scrubber has performed better than expected and without question has helped to restore the health of my reef aquarium. Since the time I purchased and built this kit, Bud has updated several aspects of the design, further enhancing performance its performance. I would without question reccommend his products to anybody looking to purchase an Algal Turf Scrubber, be it a finished product or a kit.
I sold my Dr. Walter Addey style dump tray ATS in preparation for putting this project online. As such I can only offer anecdotal evidence that this unit easily outperforms the dump tray scrubber. For what it's worth, there is no comparrison! The waterfall style scrubber wins hands down!
Bud hosts a forum at his website www.turbosaquatics.com, where you can find information regarding waterfall scrubbers. I highly recommend his forum, as it is full of knowledgeable people willing to help those new to this type of filtration.