Hi All
Yes I am a newbie, and have been reading a lot of the comments and ideas about filtration. My pond size 5000L, two pool sand filters one is filled with one bag of 3.5mm Silica the other filled with a whole lot of plastic hair curlers old fish scoop netting etc to be a Bio filter and finally a 300mm UV light. A waterfall and a water fountain.
Firstly I have been using the wrong size sand(been using normal swimming pool sand) and have purchsed the 3.5mm Silica. I have read though, an alteration to the finger of the sand filter must be done.
Can someone post a drawing or photo of this alteration please.

Yes correct this modification has to be done for successful koi pond filtration.
I have been doing these alterations on a regular basis. The sand that you are referring to is actually a 3 to 5mm particle sand. Meaning that the smallest will be 3mm and the largest 5mm. This is the correct sand to use for koi pond filtration.

The changing of the complete hub with koi pond fingers fitted is rather important on both your filters even if the one is acting as a bio filter. for which it will be fine.

These fingers come complete with a hub as well as a union these days and the installation thereof is rather simple to do for the average DIY person. They are obtainable from any Ultrazap supplier.

You can contact me should you require any more assistance on this.