There have been quite a few questions on how to mod a Koralia in order to use it with a wavemaker. So I have decided to post a little "how to" for this simple mod.  

I have been using this method for well over a year on 2 of my pumps and have had it on the other 2 for three months without any issues.  The only problem I have ran into is after about 6 months you need to replace the piece of airline because it can expand and no longer "silence" the prop.

I do want to mention that this is what worked for me, however I am not responsible for any damage that occurs to your Koralia pumps from this mod or from using them on a wavemaker.

Step1.

Get a Koralia powerhead, a #4 was used in this picture.

Step 2. 

Remove the front cover of the Koralia

Step 3.

Get some airline

Step 4. cut approx. 1/4" of the airline off.  (this piece may need to be trimmed down per your application)

Step 5.

Place the piece of airline over the shaft metal shaft between the prop and the outer housing. 

Step 6.

Put the frount housing back on the Koralia. Your final mod will look like this.

Step 7.

Try it out in either your tank or a bucket of water, you may need to trim the piece of airline to make sure it is the right size for your application.

*note 

The purpose for the tubing is to create a "silent" stop for the prop. Typically when you turn on a Koralia and the prop goes the wrong way, it forces it out towards the front of the housing and makes a loud clicking noise before having the prop start the correct way. The small piece of tubing allows the prop to extend far enough to get the prop running the right direction without the "clicking" noise, therefore making them run silent. What is the problem you are having? if the tubing piece is too long the prop wont always turn in the correct direction. if it is too small, you will have the same "clicking" problems.

Here is a little video of Before and After ( you can actually hear the clicking of the power switch in these)

Before

After