My ducks don't like their pond

[DRdM]

I have 4 Penkins and a larger pond in their enclosure (6'x8'x3.5'). They highly prefer to use it when there is running water into it. I have a big 1000L biofilter which runs with a 3500G/H pump. The outflow is a 2" pipe that drops the water down from about a foot above the pond. I had to shut it off one day before work because the filer was clogged and they didn't use the pond at all while I was gone (we have a camera set up to remote check on them).

 

[Sugarbean1966]

They can get in and out with no problems! This is an old picture (I promise the area is a lot cleaner now, so please no judgement!) There is also a ramp to help them get out.

What type of pond is that? Looking for something for our 2 ducks as they love the deep water.