Oh my. From what I've heard, ducks are filthy, and I mean filthy when it comes to 'waste'. I'd be hesitant to run any sort of filtration system in the water. Can you do the filters somewhere near the pond, but not IN the pond? You're forever going to have to enter the water to clean the system, and I wouldn't want to basically be wading into a sewage treatment pond every few days.

Also, I've heard that lava rock while economical can plug up fairly quickly, and that would impact your water flow, and ultimately filtration.

Also, how many ducks are you talking about? Also, have you checked YouTube for videos? Type in Duck Pond Filtration systems, and several videos come up. You could get some great ideas from there.

Good luck.

I don't have a serious filter system so I am not the best source, but I am under the impression that this kind of filter needs cleaning every so often. I assume lava rocks are heavy and you would be adding all the other weight too and wouldn't easily get at the filter to clean it.

Don't know the reason for the lava rock or bio balls...no mention of fish in the pond. But if you're trying to make a combo bio-mechanical filter it does "work" kind of. I mean you can throw a couch into a pond and bacteria will grow on it and dirt will stick to it so it does "work".

The reason combo filters went out of favor many years ago by serious pond keepers has a few reasons

First, the thing about ammonia and nitrite converting bacteria is they need O2 and a clean surface to grow on.

You're pumping the lowest O2 water from the pond bottom into submerged lava rock and bio balls. Trickle Towers replaced submerged media filters because they added way more O2. Shower filters then replaced TT as the best because it added more O2. I think I skipped one, can't remember. So submerged media is strike one.

To convert ammonia and nitrite bacteria have to be able to get to the ammonia and nitrite. Unless you're pushing an unbelievable amount of water thru the lava rock and bio balls muck will accumulate on them. The bacteria can do it's job covered by even the smallest amount of dust. TT and Showers solved that problem by 24/7 washing the media. The old submerged filters ammonia conversion rate drops as the media collects dirt while TT and Showers remain more steady. Steady is good. Dirty media is strike two.

As a mechanical filter sponges and mats do collect dirt, but not very much. They were state of the art 15-20 years ago. The Skippy and such. Still very popular with water garden people who don't really need a filter and these are a lot of fun to build and look impressive. Pads were replaced by settling chambers and now sieve filter for remove big stuff. Then sand and gravel filters for smaller stuff. Sponge, mats, pads can work but cleaning that bad boy a few times a week and in short order you'll call strike three.

No combo bio-mechanical filter has not yet been found to do both
well. Bead filters probably came the closest but also don't measure up. Still a fair number of people holding onto the dream though.

The current up an comer imo is the 24/7 drip filter system. A continuous drip of water (even city water) into the pond and an overflow. In not heavy fish load ponds it gets rid of all the filters. Waste water is used for landscape irrigation so no actual waste. It's been slow to be accepted. People who have installed $20,000 worth of filters are not going to toss that for a $20 drip system. They'll stick to their guns for years and years.

hi

I've kept duck ponds in the past mostly mandarins and woodies ,teal. The main problem is pollution as you know lol. very difficult to combine with fish/plants for many reasons. What I did was spend my money on a water change system, used water went to garden new water was either rain or tap.

Once weekly 50 percent change kept it in fairly good condition and the water was not wasted . and I had fantastic tomatoes (fenced in of course) lol Filtration was almost impossible particularly biofilters. obviously they keep mixed displays in zoos . Since you're on a hill gravity fed should be relatively simple ??? good luck gary

Waterbug

I have a 1500 gal pond with a 100 gal tub that acts as WF and filtration with yellow flag iris , water hyacinth and a bag of lava rock sitting on top of corrugated PVC that brings the water into the tub. There is a valve at the lower back that allows me to remove water but it is currently piped under ground to dump the water into the street. Do you have any info on how I can collect the waste water and then use it in garden

I would not do shelves. They slump/loose there shape and then are not flat enough to hold plants and they make it easier for predators to get in and out of your pond. You can build things that will elevate your plants and will act as places for fish to hide. Plastic milk crates with big flat rocks on top of them work great. An upside down black plastic plant pot with PVC legs zip tied to the pot work well too. (The legs need to be put together with 2 elbows to make a 'U' and 2 pairs of these legs can be zip tied to the pot after drilling holes to thread them thru in the corners of the pots. You can then add a lesser angled elbow to each leg to make the legs angle out from the pot to be more stable.) I need to take some pictures to show what I mean.