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Author: Biju Uthup  
Title:  An Improved DIY Sump Filter for My Aquarium
Summary:  Biju shows how he made his own do-it-yourself aquarium filtration system. It was much less expensive than commercial canister filters. Illustrated with many photographs.

Contact for editing purposes:
email:  Author, at:

Date first published: November 2004
Publication: Aquarticles 
Reprinted from Aquarticles:
March 2005: translated into Hebrew language on of Tel Aviv, at:
Internet publication (club or non-profit web site):

1. Credit author, original publication, and Aquarticles.
2.  Link to  and original website if applicable.
3.  Advise Aquarticles
Printed publication:
two printed copies to:
Madhu Soodhanan,
c/o Hon. Secretary,
Aquarists Society of Karnataka,
Government Aquarium,
Cubbon Park,
Bangalore-560 001
And one copy to:
#205 - 5525 West Boulevard
Vancouver, British Columbia
V6M 3W6

An Improved DIY Sump Filter for My Aquarium
A photo feature

By Biju Uthup
of India

The best way to describe how I recently made my sump filter is with a step-by-step photo feature. The sump filter that I built was up and operational for about three months. After three months I completely dismantled and cleaned the filter. I used that opportunity to take a few photographs as I re-assembled it, and have used them for this article.

The size of my aquarium is 3' x 18" x 15". The filters I had before were bought from a Local Fish Shop (LFS), and since I was new to the aquarium hobby I bought a system which was recommended by the LFS. The filters that I bought from their suggestions were an undergravel filter and a fully immersed filter. Initially I had not planned for a planted aquarium and had thought of just keeping a few fish to keep my daughter happy.

Well, I soon began to search the Internet for fish keeping and the aquarium hobby, and bumped onto the A-S-K Yahoo discussion group on aquaria issues specific to the Indian subcontinent. I joined this group and have learned a lot from all the discussions, initially as a silent observer and later getting involved in the discussions. I was particularly interested in DIY filters, and several people came forward with their DIY filter designs in the forum. Two such designs were posted after I joined the A-S-K group. I waited for more DIY filter designs to come up before actually choosing the best (according to my assessment) and then improvising on it. One filter design that caught my attention was a sump filter design by Venkat posted in the Indianaquariumhobbyist web page at:
His filter illustrations are reproduced here:

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I decided that this was the type of filter I wanted, since it would provide ample space for keeping the heater, CO2 reactor and other stuff that would  otherwise occupy space in the main tank and spoil the beauty of the tank. Moreover, the cost of the filter is only a fraction of the commercial Eheim filters. The main cost of this sump filter is the glass casing of the filter, and the powerhead (which may not be an investment as one can use the powerhead of older filters).

One of the main drawbacks of Venket's filter was the enormous effort required to clean it. So my modification to the filter was to solve this problem and make it easier to clean once in a while. This will become apparent as I describe the filter in the following photo feature:

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Figure (1) Front view of the sump filter tank, showing dimensions.

Figure (1) shows a front view of the sump filter glass tank. I had this tank made by an LFS at a cost of RS 450/- (US$10). (It would have cost less if I had made it myself; however I did not want to take the chance without having any experience in making glass tanks myself).

Chamber 1 is the chamber into which water is pumped from the main tank via a powerhead. Chambers 2 and 3 contain the filter media in four plastic boxes. The width and the size of chambers 2 and 3 were dictated by easily available plastic boxes for my filter media, as these boxes have a base of 5" x  4.5". Chamber 4 is the final chamber, where the CO2 reactor and the water heater are kept, and from which the water re-enters the main tank through a PVC pipe fitted in a hole drilled about 2" from the top of the tank. This PVC pipe is clearly visible in figure (1) & (2).

The glass partition between chambers 1 & 2 is 1" short at the top to allow water to overflow into chamber 2 from chamber 1. The partition between chambers 2 & 3 is raised from the bottom by 1" to allow water to enter chamber 3 from chamber 2 at the bottom. Finally, the partition between chamber 3 & 4 is short by 1.5" to allow water to overflow into chamber 4.

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Figure (2) Isometric view of the sump filter tank.

Figure (3) shows the filter cartridges made out of plastic boxes used to keep stuff in a refrigerator. The dimension of the boxes is 5" x 4.5" and this dictated the size of chambers 2 & 3 which keep the filter media. Holes are made at the bottom of the box to allow water to flow through the bottom of the boxes. Also, holes are made in the top of the box to make a handle to lift the box with the filter media during cleaning of the filter.

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Figure (3) Filter cartridge box to keep filter media

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Figure (4) Filter media

Figure (4) show the four types of filter media used in decreasing order of sizes.

The biggest filter media (1) consists of broken pieces of porous rock roughly one inch in size. (Alternately this could also be broken pieces of brick). These rocks have a lot of pockets due to air bubble formation and look like some kind of volcanic rock, which I happened to bump into. The air pockets form an enormous amount of surface area for the useful bacteria to form colonies.

The next filter media (2) consists of ceramic rings, which are easily available from an LFS.

The third filter media consist of broken pieces of rock of the order of 6-8 mm.

The final media consists of sand particles, 2-3 mm in size. You can choose your own filter media that you feel are better for your purpose and are easily available to you.

Figure (5) shows the filter media being placed into the plastic cartridges with string handles. During cleaning the filter media can be easily removed from the sump filter with the help of handles made out of plastic string.

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Figure (5a) Coarse filter media (rocks with air holes) being filled into plastic cartridges

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Figure (5a) Filter media (ceramic rings) being filled into plastic cartridges

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Figure (5b) Finer filter media (pebbles), and (5c) finest filter media (fine sand) being filled into plastic cartridges

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Figure (6) Filter media in their respective cartridges

Figure (6) shows all the filter media in their respective cartridges.

Figures (7) show how the outlet from the powerhead is fitted with a pre-filter to remove big particles like old plant leaves etc. The first pre-filter is made out of part of my old undergravel filter base and a second pre-filter is made out of plastic window mesh, as can be seen from the figures.

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7a, 7b, Fitting components

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7c, 7d,  Pre-filter fitting

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7e Completed powerhead outlet with pre-filter

Next, the cartridges with the filter media are placed into chambers 2 and 3 of the sump filter, as shown in figure (8).

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Figure (8) Filter media cartridges with filter media being placed into the sump filter chambers 2 & 3

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Figure (9) View of last chamber of the sump filter, with heater and DIY CO2 reactor

The 4th chamber holds all the equipment which normally occupies space in the tank. Heaters and a CO2 reactor can be kept in this chamber as shown in Figure (9)

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Figure (10) DIY stand for keeping the sump filter on an elevated platform

The sump filter should be kept at a level higher than the main tank. This is to enable the water to flow through the sump and overflow back into the main tank by the force of gravity. A DIY platform on which to keep the sump filter behind the main tank is shown in figure (10).

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Figure (11) Powerhead to pump the water from the main tank

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Figure (12) Powerhead fitted and placed in the main tank

The powerhead used to pump the water from the main tank to the sump filter is shown in Figure (11). I have used the powerhead of my old under-gravel filter. Figure (12) shows this placed in the main tank along with the plants and fish.

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Figure (13) Several views of the sump filter in operation

Figure (13) shows the sump filter working when the powerhead is switched on. You can see the water overflowing into the various chambers of the sump filter. The sump filter is placed on the elevated platform behind the main tank. There is ample space beside the sump filter to keep the DIY CO2 generator, as shown in Figure (14). A full view of the tank is shown in Figure (15) with the sump filter concealed behind the main tank.

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Figure (14) DIY CO2 generator behind the tank

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Figure (15) Full view of tank with sump filter concealed behind the main tank

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Figure (16) DIY CO2 reactor in operation inside the sump filter