RS7000 HANG ON FILTER

A hang-on-back (HOB) filter clips onto the aquarium's rim, with an intake tube reaching into the water and the filter body sitting outside on the back edge. Water is drawn up into the unit, passed through internal media, and returned to the tank in a steady flow over the rim — keeping most of the filtration hardware out of the display area.

The RS7000 is the top of the RS hang-on filter range, running at 4.5W with a rated maximum flow around 600 L/H. Like the rest of the RS series, it combines mechanical filtration (a sponge or floss pad catching debris and particles) with biological filtration (the media surface hosting beneficial bacteria that convert ammonia and nitrite from fish waste into far less harmful nitrate).

Because the bulk of the unit lives outside the tank, servicing it — lifting it off, opening the media compartment, rinsing or swapping pads — doesn't require disturbing decor, plants, or fish, which is the main practical advantage of hang-on-back filtration over fully internal filters.

Sitting at the top of the RS hang-on range, the 7000 makes most sense for tanks whose stocking level or waste output the smaller RS1000/2000/3000/6000 models would genuinely struggle to keep up with. Filtration capacity is really about media surface area for beneficial bacteria as much as raw flow rate — a filter run past its comfortable bioload will show it through rising ammonia/nitrite readings even if the water still looks clear.

If the cartridge includes activated carbon, a third chemical filtration stage is added on top of the mechanical and biological ones: as water passes through the carbon, dissolved organics, tannins, odors, and mild discoloration are adsorbed out, keeping the tank looking clear and neutral-smelling on top of being biologically safe. Unlike the ongoing mechanical/biological stages, carbon's adsorption capacity depletes over a few weeks and needs periodic replacement to keep working.

The RS7000 runs on mains electricity at 4.5W and needs a nearby wall socket — as with any submerged/wet electrical appliance, route the cord through a drip loop and use an ideally RCD/ELCB-protected socket.

It hangs directly on the tank's back or side rim, so an accessible open edge of suitable glass thickness is needed for a secure clip fit; it's not designed for fully enclosed rimless tanks without a proper lip. At 600 L/H rated flow — the top of the RS hang-on range — it suits medium to larger single tanks better than nano setups; as always, real in-tank turnover runs lower than the rated figure once head height and media resistance are factored in.

Run it for a day or two without fish before stocking to confirm steady flow and no leaks at the intake or return. As with any new filter on a new tank, the beneficial bacteria that actually make the water safe for fish need several weeks to establish on the media — the filter alone doesn't make an uncycled tank instantly ready for a full stocking list.

Being the highest-output unit in the range, the return splash is correspondingly stronger — position it away from surface-breathing fish like bettas or gouramis if they seem bothered by it, and consider a lid to contain splash and cut down on evaporation.

Load the media chamber before first use and prime the intake tube with water so the motor draws water immediately on power-up rather than running dry. Because it moves the most water of any RS hang-on unit, double-check the rim clip is seated firmly and level before filling the tank, since a unit under stronger flow-driven vibration is more prone to working loose over time than a smaller, gentler model.

Real-world specifications and upkeep:

• Power: 4.5W, mains electricity
• Rated output: approximately 600 L/H maximum (actual in-tank turnover is lower once head height and media resistance are accounted for)
• Suitable for: medium to larger freshwater or saltwater tanks — the top-tier unit in the RS hang-on range
• Media/cartridge: rinse the sponge or floss pad in removed tank water (never tap water, which kills beneficial bacteria) every 1–2 weeks, replacing worn media roughly every 4–6 weeks depending on bioload
• Impeller: check periodically for hair, debris, or snail shell fragments, the most common cause of reduced flow or unusual noise over time
• Water level: keep the tank close to its usual level, since an exposed intake will reduce flow or cause the filter to run dry
• Intake protection: use an intake guard or pre-filter sponge if keeping fry, shrimp, or small snails, since a filter this size can otherwise draw them in
• Priming: after a power interruption, flow may need re-priming rather than indicating a real fault
• Splash: a lid contains return splash and reduces evaporation from the stronger surface agitation this top-tier unit produces
• Rim fit: confirm the clip sits level and secure on the tank edge before filling, since a poor fit can allow shifting or leaking
• Staggered media changes: avoid swapping all the media at once if it combines mechanical, biological, and chemical portions in one cartridge — replacing everything together resets the bacteria colony and risks a small ammonia spike; rinse and reuse the biological portion where possible and replace only the chemical (carbon) portion on its own schedule
• What to avoid: never rinse media under hot tap water or with soap/detergent — both kill the bacteria colony and can leave a residue that's harmful to fish even after rinsing