I have a duck pond that's about 3000-4000 gallons. The ducks fertilize it all year round, so without a filter and aeration and plants consuming excess nitrogen, it gets dirty once the temperature of the water gets warmer. I've tried a few different approaches to filtering the pond over the past few seasons including poly filter media, top down gravity filters, and PVC pipes filled with gravel. The best so far was the PVC gravel, which does a nice job cleaning the water, but eventually got clogged. This barrel is basically a huge version of that, and should hopefully last all year without maintenance.I'm currently trying this barrel out as a closed/pressurized system where the incoming water is injected into the bottom of the container, and the outgoing water passes through several layers of sand and gravel. So far it seems to be working well, and the barrel is up to the task. The seal around the lid held with no problems at all. I just had to cut a couple of holes in the top of the container and install some bulkhead fittings run a PVC pipe to the bottom of the barrel and fill the barrel with media.You could easily use this to make a swirl filter, or even use it as a low-pressure accumulator if you threw some air-holding bladder or ball inside. I don't think it will hold a huge amount of pressure (the lid is probably the weak point), but I was pleased to see it could withstand at least the modest amount of pressure that my pond pump can produce.
Rating: [5 of 5 Stars!]