Filter Gantung (Hang On Back Filter): Pros, Cons & Setup for Malaysian Tanks
A filter gantung (hang on back or HOB filter) hooks over the back rim of the tank, pulls water up through an intake tube, runs it through media in a box, and spills it back like a small waterfall. It is one of the easiest filters for 1 kaki and 2 kaki tanks: cheap, quiet when set up well, easy to clean, and it takes no space inside the tank. The trade-offs are a smaller media capacity than a canister or top filter, an open gap at the back for the lid, and a habit of losing its pull when the water level drops. This guide covers choosing, setting up and troubleshooting one.
How a Filter Gantung Works
- An impeller in the motor draws water up the intake tube (with a strainer at the bottom).
- Water passes through mechanical media (sponge or floss) to catch debris, then biological media (ceramic rings or sponge) where beneficial bacteria live.
- Water overflows the lip back into the tank, which also stirs the surface and adds oxygen.
That surface splash is a real bonus in Malaysia. Tanks at 28–31°C hold less oxygen, and an HOB's waterfall helps without a separate air pump in a lightly stocked tank.
Pros and Cons
| Pros | Cons |
|---|---|
| Cheap to buy and run | Small media space compared with canister or top filter |
| Easy setup: hang, fill, plug in | Needs water level near the lip, so evaporation affects it |
| Media easy to reach for cleaning | Open gap at the back makes lids awkward (jumpers can escape) |
| Surface agitation adds oxygen | Strong intake can suck in shrimp or fry without a guard |
| No tubing to leak under the cabinet | Waterfall can be noisy if the water level is low |
| Works on rimless and rimmed tanks (check thickness) | Not enough for big messy fish like goldfish in 3 kaki tanks or arowana |
Which Size for Which Tank?
Aim for a flow of about 4–6 times the tank's water volume per hour, and more for messy fish. Real-world flow is lower than the box says once media is packed in.
| Tank size | Approx. water | Suggested HOB rated flow | Good for |
|---|---|---|---|
| 1 kaki (30 cm) | ~12 L | 100–200 L/h, with adjustable flow | Betta, shrimp, nano fish |
| 1.5 kaki (45 cm) | ~28 L | 200–300 L/h | Guppies, small tetras, rasboras |
| 2 kaki (60 cm) | ~55 L | 300–450 L/h, or two small units | Community fish, small planted tanks |
| 2 kaki with goldfish | ~55 L | 450 L/h+ or add a sponge filter | Goldfish make a lot of waste |
| 3 kaki and up | 150 L+ | HOB only as an extra | Use a top filter or canister as the main filter |
For the litres in each size, see our tank size guide. Browse current models and RM prices in Hang On Filters, and check the listing for rated flow, glass-thickness limit and whether spare impellers are available.
Setup: Step by Step
- Rinse the media in dechlorinated water, never just tap water if it's already seeded.
- Hang the filter on the back glass and check it sits level. A tilted HOB overflows on one side or runs noisy. Many have an adjustable leveller.
- Fit the intake tube so the strainer sits a few cm above the substrate, low enough to pull debris but not sand.
- Fill the tank to about 1–2 cm below the filter's lip.
- Prime it: pour tank water into the filter box until it's full before switching on. Many HOBs aren't self-priming, and running dry damages the impeller.
- Plug in and listen. Some gurgling at first is normal while air escapes.
- Add a drip loop to the power cable so any drip runs off the loop instead of into the socket.
Media Upgrades That Make a Big Difference
The stock cartridge (floss with carbon) is the weak point. You throw it away every few weeks, and the bacteria go with it. Better:
- Swap cartridges for a coarse sponge plus ceramic rings or bio-balls in the media box. Keep the bacteria; just rinse the sponge in old tank water monthly.
- Add a thin layer of filter floss on top for polishing. That's the only bit you replace.
- Use carbon only when needed, e.g. to remove medicine after treatment. It is used up within weeks.
- Look for sponge, rings and floss in filter accessories.
Our filter media order guide explains how to layer media for the best results.
Shrimp-Safe and Fry-Safe Intakes
A strong HOB will suck in baby shrimp, guppy fry and even small fish. Fixes:
- Slide a pre-filter sponge over the intake strainer. It also adds bacteria surface and keeps the main media cleaner.
- Turn the flow down if your model has a dial.
- For a betta, reduce flow or baffle the outflow with a sponge. Long-finned bettas tire in strong current. See cara jaga ikan laga.
Filter Gantung Tidak Menyedot Air: Troubleshooting
When the filter stops pulling water, the usual causes are:
| Problem | Likely cause | Fix |
|---|---|---|
| Motor hums, no water flows | Lost prime (air in the intake), often after a power cut | Top up the tank, fill the box with water, restart |
| Weak flow | Clogged sponge or pre-filter | Rinse media in old tank water |
| Very weak or no flow, motor rattling | Dirty impeller or broken impeller shaft | Pull out the impeller, clean slime, replace if worn |
| Loud waterfall splash | Water level too low (evaporation) | Top up with dechlorinated water |
| Overflowing the back | Media too packed, or filter not level | Loosen media, adjust leveller |
| Stopped after a few hours | Air lock in the intake tube | Remove intake, fill with water, refit |
Evaporation is fast in warm Malaysian rooms, and a fan cooling the tank speeds it up further. Top up every few days. Read air akuarium berkurang: aquarium evaporation for why.
After a power cut
Most HOBs restart on their own, but some lose prime when the water in the box drains back. Check your filter is flowing after every TNB outage. If it was off for hours, rinse the media in tank water before restarting, as stale water in the box can release a burst of dirty water.
HOB vs Other Filters
| Filter | Best for | Compared with HOB |
|---|---|---|
| Sponge filter | Fry, shrimp, betta | Gentler and cheaper, but needs an air pump and takes space inside |
| Internal filter | Small tanks, hospital tanks | Sits inside the tank, less maintenance access |
| Top filter (filter atas) | 2–4 kaki tanks, goldfish | Much more media, the Malaysian standard for bigger tanks |
| Canister | Planted and large tanks | Quiet and powerful, costlier and harder to clean |
FAQ
Filter gantung sesuai untuk akuarium berapa kaki?
Paling sesuai untuk akuarium 1 kaki hingga 2 kaki. Untuk akuarium 3 kaki ke atas, guna top filter atau canister sebagai penapis utama, dan filter gantung hanya sebagai tambahan.
Kenapa filter gantung tidak menyedot air?
Biasanya sebab air dalam akuarium terlalu rendah, ada udara dalam paip sedutan, atau span tersumbat. Tambah air, isi kotak penapis dengan air dahulu, dan cuci span dengan air akuarium. Kalau masih tak jalan, periksa impeller.
Is a hang on back filter enough for a betta?
Yes, if the flow is adjustable or baffled. Bettas don't like strong current, so turn it down or put a sponge over the outflow.
How often should I clean a filter gantung?
Rinse the sponge in old tank water every 2–4 weeks, or when flow drops. Don't replace all the media at once, or you lose the beneficial bacteria.
Can I use a hang on back filter with a lid?
Yes, but you usually need to cut a notch in the lid or use a lid with a cutout. Cover any gap if you keep jumpers like bettas.
Ready to upgrade? Browse hang on filters, filter media and other aquarium filters from sellers across Malaysia on FishyHub.