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HOG2 Hang-On-Glass UAS Upflow Algae Scrubber with Green-Grabber surface - 2 cubes feeding per day


Eliminate water changes. Remove nuisance algae, nitrate and phosphate. Cultivate seaweed for feeding!!!


HOG2 dimensions: Each cover is 6 5/8" wide x 8 3/4" high x 1 1/2" thick  (16.6cm wide x 21.9cm high x 3.75cm thick).


Operates on both 120 and 240V. 


***Can ONLY be shipped in USA.***


No dangerous metal 240/120 volt lights.


Welcome to algae scrubbers. We are the only source for patented upflow scrubbers: U.S. Patent 9,115,008 and 9,708,207. All the oceans, reefs, lakes and rivers are naturally filtered only by algae, and all the organic particles remain in the water to feed the creatures. Reduce your glass cleaning and water changes, and create an environment for living micro-animals to grow inside the scrubber. No more dosing or possible overdosing. No more refilling. No more pale corals from low nutrients, and no more sick animals from high nutrients. Far more powerful than chaeto or refugiums, and does not remove the food particles. And you can use the algae as food!


Get the no-overflow advantage of an upflow scrubber: since it is ALL underwater, it can't overflow onto your floor. And now, all six of the magnets that go in the water are protected by a hard plastic cover inside of the black silicone; this prevents any scrapes or rust if you happen to accidentally let the magnets snap together. 


This is the first larger Hang-On-Glass version of the standard HOG.5,  HOG1  and  HOG1x algae scrubbers, which were the first HOG scrubbers available. This HOG2 offers much larger algae-attachment space to hold more growth between cleanings, and also stronger magnets to attach to thicker aquarium walls up to 5/8" (16mm) glass or acrylic. If your tank is larger than a nano, then you can consider this model or larger.


This HOG2 Scrubber has 48 square inches (300 square cm) of one-sided algal growth surface, which once growing is designed to absorb the nutrients from this much feeding per day: 


2 Frozen cubes, or

20 Pinches of flake, or

20 Square inches (125 square cm) of nori, or

5.6 grams of pellets


The number of gallons or liters of water in your tank or sump does not matter. If you feed more than the above amounts you can get multiple HOG2 units; multiple units are preferred over one larger unit because you can clean one unit per week, and because you'll always have one unit filtering while the other one starts growing again after a cleaning. Multiple units are also good for backup. The magnets attach the outside cover to the inside cover through the aquarium wall, and can be used on glass or acrylic 1/4 inch (6 mm) to 5/8 inch (16 mm). Not more. If your aquarium wall is 3/4" (18mm) it might work but you won't know until you try; it would be better to put the HOG2 in your sump instead; it will work the same. 


Compared to the HOG1.3 and HOG3 which look the same in size, the HOG2 is meant for situations which have some nutrient or algae problems but the rocks in the display are not covered in thick green hair algae. The large inside space of the HOG2 growth compartment allows for lots of build up of algae, and the 4 LED light grows green algae in situations where the lower power of the HOG1.3 would only grow brown algae. So this HOG2 model is great for aquariums that have been running for a year or more and the display rocks have already filled with phosphate, and are thus starting to show algae on them. However if the display is full of green hair algae and thus the nutrients measure zero in the water (because the algae on the rocks is absorbing them), then the stronger photosynthesis of the HOG3 would be better than this HOG2, so as to be able to out-compete with the photosynthesis on the rocks.


The Green-Grabber (tm) algal growth surface is so rough and prickly that it might be the roughest thing you've ever felt. A cactus might be sharper, but that's about it. Rough surfaces are critical for allowing algae to attach and grow and thus provide strong absorption of nutrients. The rock-hard protrusions stick straight out 1 to 3 mm. Old style algae scrubber screens are made from "slippery" plastic canvas that is used for sewing and knitting; algae takes a long time to attach to it. Green-Grabber (tm) growth surfaces are not plastic at all; instead they are rock hard and have jagged rough edges and points (don't let children play with them). Green-Grabber surfaces are so good at grabbing algae and letting it grow that if you have high nutrients you may starting seeing tiny growth spots within hours instead of days. And the white color of the Green-Grabber surface reflects as much light as possible, getting almost the effectiveness of a 2-sided growth surface even though it really only has a light on one side of the surface.


This is a hand-built Hang-On-Glass® (HOG) Upflow Algae Scrubber® (UAS) with a Green-Grabber growth surface, for glass or acrylic 1/4 inch (6 mm) to 5/8 inch (16 mm) thick. This is the typical thickness range for most aquariums, and larger sumps, however you should measure yours to be sure. If your tank uses thin 1/8" (3mm) glass such as many low-cost 10 gallon aquariums do, this filter is not recommended because the magnets are strong enough that they might crack the glass. You would be better off getting a lower cost HOG.5 filter HERE


No electrical parts go inside the aquarium; only air. And the air bubbler is already supplied (it's sealed behind the growth surface), so you don't have to get an airstone. The bubbler is simply vinyl air hose that has been cut lengthwise, and with cross-cuts, to form little flexible segments that are both adjustable and open-able to allow for easy cleaning. This HOG2 will run on both 120V and 240V, and comes with a 10 ft (300 cm) power cord with a U.S. plug.


Comes with 3 ft (90 cm) of vinyl airline, but requires an air pump that can pump at least 2.0 liters per minute (.07 cfm), preferably more. A pump that says it can handle 2 or more airstones/outlets, or a pump with 2 tubing attachments instead of one, will be needed. You can have as much air as you like, however; 10 lpm pumps are no problem (although it will be louder). One powerful pump which works exceptionally well is the Whisper AP 300 from Tetra. 


Comes with 4 red (660 nm) 3-watt LEDs, which are attached to a heat sink inside the cover. The LEDs will give the aquarium or sump a slight red color at night when the aquarium lights are off. You may need to get a timer so you can run the LEDs for up to 22 hours per day depending on the color of the growth. The LEDs never needs replacing. 


The HOG2 growth surface will need to be cleaned every 7 to 21 days, by removing the inside cover, disconnecting the airline, and taking the inside cover to the sink so you can brush the algae off of the growth surface and the bubbler with a toothbrush.


Visit the Santa Monica Filtration Website for the full description: