# The Crown of Thorns - surface skimmer



## essabee (Oct 11, 2006)

It’s quite a simple gadget. An upside down sponge filter drawing water from the surface. I used a 6” piece of pipe, 2" dia, for the body of the sponge filter (3” total of sponge and filter watte). The top is open and the bottom is a 2” socket fitted with a 1” adapter and small bit of 1” pipe fitted to the suction of a power head.

What actually special is the top intake. I have made vertical cuts, 1.5” long from the top, spray bar style, so that the water is drawn from the sides of top of the 2” pipe. I thought that 1.5” would be maximum difference in surface level of a tank. You have to set the surface skimmer so that its top is just higher than the highest level you would top up the tank.

Now if you have followed me till this point, you would say that the water will be drawn from the entire vertical 1.5” slits. No, it is not drawn from the entire slit but from the surface only. Inside the 2” pipe is a floating cylinder, vertically 1.75” which effective shuts off the slits. When you put the power head on; the water level in the 2” pipe falls and with it the floating cylinder, so only the surface water is drawn in. If the floating cylinder drops too much then the water flows in too fast and the height of the water in the 2” pipe rises; so does the floating cylinder cutting of the deeper water. So it is only the surface water which is drawn in.

I made the inner floating cylinder from the material of a soda pet-bottle. Used a band of epoxy putty at the bottom and a band of Styrofoam at the top.

The output of the power head can be directed at will, so if you want to avoid surface agitation, it’s simple to direct the output water away from the surface. Actually the entire design and execution was meant to find a way to deal with surface scum without agitating the surface.

I had not taken any pics while constructing as I was in doubt if it would function to my satisfaction. It was on all night and the surface this morning was crystal clear, quite a big surface 3'x 6'. Now I have a few pics of the gadget in place for you to view. The pet bottle you see in the background is my reactor device for DIY CO2.


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## Volenti (Oct 12, 2007)

Now that's a good idea, nice job.


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## hoppycalif (Apr 7, 2005)

That is a really good idea, and simple to make too. Many of us have a powerhead in the tank for extra water circulation, so this gives that powerhead another job to do. Where does the collected stuff end up? How often do you need to clear it out?


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## essabee (Oct 11, 2006)

hoppycalif said:


> That is a really good idea, and simple to make too. Many of us have a powerhead in the tank for extra water circulation, so this gives that powerhead another job to do. Where does the collected stuff end up? How often do you need to clear it out?


Thankyou. Just made it, only 36 Hrs of experience with it, so cannot reply completely. Cleaning it would not be a problem as I have not used any adhesive for the 2" socket and all the filter media is there so shall be the scum. Just clean it like a sponge filter I expect.


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## Grubs (Jul 4, 2007)

The floating cylinder inside to block off the slits is an ingeneous solution to maximise surface water extraction without having the entire crown floating as the fluval extarctors do. Good one.


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