Thanks for your replies folks, and BlueandKim, your tank looks awesome!
Well, I went to the LFS and bough some little black filters (I think Aqua ones), just 4cm x 3cm size. I cut them round to fit the outlet bottom. Also made them about 1.5cm high. This helped reduce the noise, also I had another one with a hole in the middle and just "sat" it on the water hole at the top. Doing all this quieten it down considerably, and it doesn't stop the waterflow by much at all. Once again, you will have to periodically check that the filter is not clogged.
While I was doing this I thought I would clean the filters as I haven't done it for a couple of weeks. I got a REAL SURPRISE! I had seen one or two brown baby bristlenoses sucking on the glass earlier. I saw one baby bristlenose trying to escape, then I saw one stuck "in" the intake! Later cleaning the filters I saw a few more, but this time it's baby Golden Bristlenoses! I have 3 brown bristles and 3 golden bristles in my tank.
So now I have also put a sponge on the intake tube so no more babies are going up the tube!!!
So for those who have an AquaOne tank, try what I've suggested above and that should fix the problem.
Cheers!