3 Frozen cubes, or
30 Pinches of flake, or
30 Square inches (180 square cm) of nori, or
8.4 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 HOG3xx units, or a combination of HOG3xx and SURF 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 1/2 inch (13 mm).
Not more. If your aquarium wall is 5/8 to 3/4" (18mm) it might work but you won't know until you try; it
would be better to put the HOG3xx in your sump instead; it will work the same.
Compared to the HOG1.3
which look the same in
size, the HOG3xx is meant for situations which have severe nutrient or algae problems, even in cases where
the rocks in the display are covered in thick green hair algae. Algae-covered rocks are the most difficult
situations to fix because the photosynthesis of that algae on the rocks is consuming nutrients from the
water (often it measures zero), making it harder for the HOG filter to get the nutrients. To combat this you
need stronger photosynthesis in your HOG scrubber, and that is what the HOG3xx is designed for. In
particular, compared to the original HOG3 and HOG3xx, the extra extra LEDs of the HOG3xx provide the highest
photosynthesis yet in this size scrubber and is suitable for the highest amount of nutrients (such as
phosphate) in the water.
The large inside space of the HOG3xx growth compartment allows for lots of build up of algae, but most
importantly the 12-LED light provides the strongest photosynthesis of all the HOGs, giving it the best
chance of out-competing the scrubber on your rocks and also cutting through the phosphate in the water as
high as 1.0 ppm. The 12 LED light grows green algae in situations where the lower power of the original
HOG3, and certainly the HOG1.3 and HOG2, would only grow brown algae or slime. So this HOG3xx model is great
for aquariums that have been running for years and are showing signs of old tank syndrome, or in highly-fed
predator or NPS corals tanks, especially where the water has very high measurable phosphate. Be sure to
follow the special instructions on reducing the light during start-up (by using the low-power mode) because
the strong light and white surfaces will photo-inhibit initial growth in the scrubber if the light is not
The strings (ribbons) in the growth compartment of the HOG3xx are the same strings that are in the SURF2,
SURF2x, SURF2xx, SURF4, SURF4x, SURF8 and SURF8x and are the heart of the ability of the scrubber to be able
to use all the space for initial growth. The HOG1.3 and HOG2 have to grow outward from the textures before
the open-area of the compartment is filled in (although they are great for freshwater); however the strings
on the HOG3xx (like the original HOG3 and HOG3xx) allow this middle open area to start growing immediately,
and do so using 2-sided growth (strings are 2-sided in growth) instead of the 1-sided growth of the textures
alone. Thus the compartment fills much faster with growth, and this faster growth causes stronger
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 2 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, for the most photosynthesis
This is a hand-built Hang-On-Glass® (HOG) Upflow Algae Scrubber® (UAS) with strings and a
growth surface, for glass or acrylic 1/4 inch (6 mm) to 1/2 inch (13 mm)
thick. This is the typical
thickness range for small and some medium 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 silicone 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 HOG3xx will run
on both 120V and 240V, and comes with a 10 ft (300 cm)
power cord with a U.S. plug for each of the two power supplies. If you require a different plug you can get an
adapter at any local hardware or travel store, or online, or you can cut off the U.S. plugs and install your own
plugs from a hardware store. They are simple 2-prong plugs.
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. You
will need to combine the two outputs into one to feed the scrubber, using something such as the "Tee" or "Y"
air line tubing fitting from Tom Aquatics. Make sure to put the air pump above the aquarium so that it will
not drain any water if it shuts off, or use a one-way valve on the airline if the pump is lower.
Comes with 12 red (660 nm) 3-watt LEDs, which are attached to a heat sink inside the cover; the cover does
get warm. The LEDs will give the aquarium or sump a slight red color at night when the aquarium lights are
off. You will probably need to get a timer so you can run
the LEDs for up to 22 hours per day (not 24), although you can start out at 24 hours as see how it grows. A
single timer to handle both power supplies is fine. The LEDs never needs replacing.
The HOG3xx growth compartment will need to be cleaned every 7 to 14 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, and also off of the strings. Sometimes though you can just
reach in an grab the growth, especially in saltwater. The Green-Grabber growth surface is permanently glued
to the inside cover using epoxy, however a few of the Green-Grabber particles may dislodge during the first
few cleanings, which is normal. Cleaning the growth surface, bubbler, and the inside cover takes about a
minute with a toothbrush.
This HOG3xx comes with a 1 year warranty: Warranty is for
replacement or repair only; not a refund. Costs for shipping back to us are covered if you are in the U.S.
Costs for shipping back to us are not covered if you are not in the U.S., however we will pay for shipping
back to you. In either case, you will need to ship the entire unit back to us before we can ship a
replacement. Warranty is limited to repair or replacement, and does not cover fish loss, personal injury,
property loss, or direct, incidental or consequential damage arising from the use of it. The warranty and
remedies set forth above are exclusive and in lieu of all others, whether oral or written, express or
implied. We specifically disclaim any and all implied warranties, including but not limited to lost profits,
downtime, goodwill, damage to or replacement of other equipment and property, and any costs of recovering
animals, plants, tanks or other aquarium related items and/or equipment. We are not responsible for special,
incidental, or consequential damages resulting from any breach of warranty, or replacement of equipment or
property, or any costs of recovering or reproducing any equipment, animals or plants used or grown with this
Can be shipped to any country; you can find shipping costs by using
the shopping cart; be sure to click "display rates". If you don't have a zip code, enter "zip code"
instead. Note that shipping outside of the USA will probably require you to also pay an import charge
when it arrives. We cannot mark it as "gift". The lowest cost (but slowest) foreign shipping is
generally USPS Priority Mail International, but USPS Priority Express International is faster. The size
of the shipping box is 12 x 10 x 6.5 inches (33 x 23 x 16 cm).
HOG3xx size: 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). It requires at least 7" (17.5cm) of water to operate in.
Comments of similar HOG3x:
"This is just one week after my first [original HOG3] cleaning; Is growing super thick green algae"
..."And this is about 2 weeks growth, compartment completely full, nitrates are at 0, phosphates are
between 0 and .25 per API, top layer was touching glass and was really yellow, when I pulled the layer off
there was a ton of algae and it was dark green" -- Nathan P.
"It's been a little over a month since I installed two [original HOG3] filters on my 165g tank. Any
algae that was growing on my rocks (just one spot) is now gone. Best part, so is any and all cyano!" --
3Twinklets on the R2R site: