Lower Reef Tank Temperature Without Chiller

28 March 2017

One forumer in the Singapore Reef Forum asked how to lower the water temperature in a reef tank without using a chiller.   Another forumer asked for a picture of such construction.  The article will tell how.

What's Needed?

a)   To form a Cooling Tower

1.  2 pieces of 4 feet x 2 feet plastic sheets that are  available from the shop that sells office light fittings.  I got mine free when my office was under renovation.
2.  One pump sump of about 1.5 feet x 3 feet or other dimension to suit requirement
3.  Industrial liquid thinner

b)  To construct a dry filtration media within the tower

1.   About 3 rolls of twine string paper

2.   1/4" plastic tubing or plenty of plastic straws

3.    Few pieces of  10 mm diameter PVC pipe each cut to about 10" length

How to Construct?

a)   Description

As I have  retired the cooling tower a long time ago. The following sketch will give some idea on how to construct the cooling tower which was located at the back of the reef tank with a pump sump below the tank.

The tower was about 4 feet tall and filled with loose packed dry media made from flatten twine paper string that has gaps to allow air and water to pass through them.  

Water is fed into the top section using 2 Nos of 20 mm U shape plastic tube and overflow reservoirs without drilling any hole in the reef tank (link) The water is then allow to go through the rain shower plate, which is basically a plastic sheet full of small holes.

 b)  Constructing the Tower

1.  Cut plastic sheet into 10"x 4 feet strips and glue them up to shape using the industrial thinner.  As thinner will normally dissolve the surface of the plastic,  it will provide a good joint without using any other glue.  To form a good seal at the joint,  run a little amount thinner alongside the joint,  to and fro several times.  Allow  the plastic joints to dry over night.

2.  Cut a piece of plastic sheet and drill as many holes of about 1/8" to form the rain shower plate to be inserted on the top section to form the rain shower.  Allow at least 6" clearance between the fan and the rain shower plate.

3.  Allow one empty section for air inlet as shown in the sketch 

c)  Constructing the filter media

1.  Unroll the twine paper string and flatten the string out so that it can be rolled loosely together again with plenty of  1/4" tube or the plastic straws inserted in between to form another roll of filter media that can be filled the inside of the entire cooling tower.   The tube or plastic straws should be as many as possible to ensure the papers will be  loosely packed and that air and water will be allowed to flow freely through the filter media.

2.  Place twine paper rolls inside tower horizontally with each roll separated by the 10 mm PVC pipe for proper air circulation in between the rolls.


This set up can cool the water  to about 27 C which is the average wet bulb temperature of our ambient air. Constant feed of light Limewater and kalkwasser is all that is necessary to replenish lost water.  I used the setup for about 2 years without any other filters although I stored some dead corals inside the pump sump.

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