DIY Trickle Filter

I first bought a 6×2x2 aquarium when I was 19 years old and at the time was still attending university in Sydney. As a full-time student, I did not have a lot of cash for expensive filtration systems such as larger canister filters or glass sumps with built in trickle filters. So a friend (thanks Stefan) who had also bought a 6×2x2 and I developed this cheaper design which hopefully will come in useful for someone else. Each of these filters (including the media) cost around $30 AUD, without the cost of the pump which was ~$70 AUD. This filter was extremely effective and coped even when the tank was stocked with large, messy-feeding central American cichlids. In the three years that I had this filter running I never had any ammonia, nitrite or nitrate and the water was crystal clear. The main advantage of these systems over traditional sump based trickle filters is firstly monetary, secondly these filters have a large volume and as such can easily accommodate shell grit/carbon and other filter additives.

Materials required:

• 1 “sump” (A clear/opaque plastic storage box (~80L) bought from a “seconds/reject” shop)

• Submersible pump (enough pumping capacity to turn the volume of the tank over two/three times an hour. Eg: for a 6×2x2 with ~700L volume a pump that turns over 2000L an hour is ideal)

• 1 small sink/vanity drain

• PVC piping to fit the small sink drain

• Plastic tubing (bought from hardware stores)

• Some electrical conduit (around 1m)

• 3 Hose clamps

• Filter material

• Coarse filter material (Used for packing/insulation)

• Fine filter wool

• Biological Media (this can be anything chemically inert with a larger surface area (Coarse sponge pieces, pebbles [although these are pretty heavy] , rubber pegs, fishing line etc)

Construction

Construction is fairly simple, firstly to prepare the sump.

1. Cut a hole into either the base (using a drill) or into the bottom of one of the sides of the sump container. This hole should closely fit the sink drain although the sink drains we purchased had two washers, one for the inside and one for the outside of the sump container, so some small discrepancies are ok. If you are paranoid about the filter leaking, the drain can also be sealed into place using silicon sealant. The sink drains are available at hardware stores and fit a range of sizes of PVC piping (for the return pipe, I used 100mm) it is important to make sure that the diameter of the return piping into the tank is several times larger than the plastic hosing that delivers water to the top of the filter. This ensures that the filter firstly operates as a wet & dry system ensuring maximum nitrification, secondly it ensures that no water pools within the filter and it therefore is light in weight and finally (and most importantly) it never floods.

2. Two holes should be drilled in the top of the container at one of the short ends, while at the other end, a single hole should be made. The holes need to be large enough to accommodate the PVC spray bars and the hosing that delivers the water to the top of the sump. These holes should be made as accurately as possible, and the holes at end (A) should be made slightly higher than the holes at end (B) as this prevents any drips running along the spray bars and leaking from the sump.

3. Hosing should then be linked from the pump to the spray bars, the pump should be positioned high in the tank, I concealed mine amongst a small rock pine several inches under the waters surface. This is another safety feature which prevents excess water being pumped from the tank in the advent of an emergency.

4. The PVC piping should then be plumbed into the tank, a range of connectors are available at low cost should you need to navigate any tricky corners. The sump itself can be supported on the tank itself (over the tank braces - mine only weighted around 6kg), especially if the media contained inside is light. In a fishroom the sump can be placed on a shelf created above the tank.

Pump selection

A range of water pumps are available in different sizes , I used a Rio 2100, while a friend used a Rio 1700 with no problems on tanks up to 700L. Eheim also make some excellent water pumps and although these are slightly more expensive they are appear to be more reliable than the Rio line. Larger pumps such as the “Silent one” pump upwards of 4000L an hour and while extremely reliable these are large volumes and the return plumbing should be of a large enough diameter to accommodate this increased volume.

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