How to Set Up a Sump Filter: Complete Guide for Beginners
This sump filter setup guide beginners can rely on breaks down everything from choosing the right sump to plumbing it correctly. At Gensou Aquascaping, 5 Everton Park, Singapore, we design and install sump systems for hobbyists who want the cleanest water and the most discreet filtration possible.
What Is a Sump Filter?
A sump is a separate tank, usually located inside the cabinet beneath the display aquarium, that acts as an external filtration system. Water flows from the display tank into the sump via an overflow, passes through various filtration media and is pumped back up to the display tank by a return pump. Sumps are common in marine setups but are equally beneficial for large freshwater and planted aquariums. The primary advantages are increased total water volume, which improves parameter stability, and the ability to hide equipment such as heaters, protein skimmers and dosing lines out of sight.
Choosing the Right Sump Size
As a general rule, your sump should hold at least 20 to 30 per cent of the display tank’s volume. For a 300-litre display, a sump of 60 to 100 litres is appropriate. The sump must fit inside the cabinet beneath the tank, so measure the internal dimensions carefully before purchasing or commissioning one. In Singapore, acrylic sumps can be custom-made by local fabricators for SGD 80 to SGD 200 depending on size and baffle configuration. Pre-made glass sumps are also available at aquarium shops for similar prices.
Understanding Sump Sections and Baffles
A well-designed sump is divided into sections by baffles, which are vertical partitions that direct water flow through different filtration stages. A typical layout includes:
- Intake section: Water enters here from the overflow. A filter sock or sponge catches large debris.
- Biological media section: This chamber holds bio media such as ceramic rings, sintered glass or plastic bio balls where beneficial bacteria colonise.
- Chemical media section (optional): Activated carbon, Purigen or phosphate remover can be placed here.
- Return pump section: The final chamber houses the return pump. The water level here fluctuates as water evaporates from the display, so the pump should sit slightly above the base.
Baffles alternate between over-and-under flow to prevent air bubbles from reaching the return pump and to maximise contact time with media.
Overflow Systems Explained
Water must flow from the display tank to the sump by gravity. The two main methods are a drilled overflow and a hang-on overflow box. A drilled overflow involves drilling a hole in the back or base of the display tank and fitting a bulkhead. This is the more reliable method, as it cannot lose siphon, but requires a tank with tempered-glass-free panels. A hang-on overflow box uses a siphon to pull water over the rim and down to the sump. It is easier to install on existing tanks but carries a small risk of siphon failure during power outages. Whichever method you choose, the overflow must be rated to handle the flow rate of your return pump.
Selecting a Return Pump
The return pump moves water from the sump back to the display tank. Choose a pump rated to deliver the desired flow rate at the head height, which is the vertical distance from the sump to the display tank’s return outlet. A turnover rate of four to six times the display tank volume per hour is a good target for freshwater systems. For a 300-litre tank, that means a pump delivering 1,200 to 1,800 litres per hour at the required head height. DC-controllable pumps, while more expensive at SGD 80 to SGD 200, allow precise flow adjustment and run quieter than AC pumps.
Plumbing the System
Use PVC pipes and fittings rated for the appropriate diameter, typically 20 to 25 millimetres for most home aquariums. Connect the overflow outlet to the sump intake section with a short length of flexible tubing or rigid PVC. Install a ball valve on the drain line to fine-tune flow rate and reduce noise. On the return side, connect the pump outlet to PVC piping that runs back up to the display tank. Add a check valve on the return line to prevent back-siphoning during power failures. Use Teflon tape on threaded fittings and PVC cement on solvent-weld joints to ensure watertight connections.
Testing for Leaks Before Going Live
Before adding livestock, fill the system with water and run it for at least 24 hours. Check every joint, fitting, bulkhead and hose connection for drips. Simulate a power outage by switching off the return pump and observing how much water drains back into the sump. The sump must have enough spare capacity to hold this back-siphoned water without overflowing. Adjust the return nozzle height or add a siphon break hole in the return pipe just below the water line to limit back-siphon volume. This testing phase is critical and should not be rushed.
Maintaining Your Sump
Clean or replace filter socks weekly, as they clog quickly and can become a source of nitrate if neglected. Rinse biological media in old tank water every few months, never in tap water, to preserve beneficial bacteria. Replace chemical media according to the manufacturer’s schedule. Check the return pump impeller quarterly for debris and descale it if mineral deposits have built up. Top up the sump with dechlorinated water to compensate for evaporation, keeping the return pump section at a consistent level. For help designing or installing a sump system tailored to your aquarium, contact the team at Gensou Aquascaping.
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