An Improved DIY Sump Filter for My Aquarium
A photo feature
By Biju Uthup
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
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
His filter illustrations are reproduced here:
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
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
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.
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.
Figure (3) Filter cartridge box to keep filter media
Figure (4) Filter media
Figure (4) show the four types of filter media used in decreasing order of
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
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
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.
Figure (5a) Coarse filter media (rocks with air holes) being
filled into plastic cartridges
Figure (5a) Filter media (ceramic rings) being filled into plastic
Figure (5b) Finer filter media (pebbles), and (5c) finest filter
media (fine sand) being filled into plastic cartridges
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.
7a, 7b, Fitting components
7c, 7d, Pre-filter fitting
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).
Figure (8) Filter media cartridges with filter media being placed
into the sump filter chambers 2 & 3
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 (10) DIY stand for keeping the sump filter on an elevated
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).
Figure (11) Powerhead to pump the water from the main tank
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.
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.
Figure (14) DIY CO2 generator behind the tank
Figure (15) Full view of tank with sump filter concealed behind the
Figure (16) DIY CO2 reactor in operation inside the