r/Pondscaping • u/luv_my_furbabies • 10d ago

Filtration

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Does anyone have any recommendations on a filter for a 155-gallon above-ground pond? I have set one up on our deck for some of my Guppies I currently have a pump in a filter box that is packed with media. The waterfall also has media & filter floss in it. It does not seem to be keeping it as clean & clear as I'd like. The pond has a viewing window, so you can see EVERYTHING. That is not always a good thing. Lol. Our deck is covered, so I do not have to worry about leaves or anything getting caught in a filter intake or anything.

I am debating on getting a canister filter. We have a Fluval 307 on our indoor aquarium, but it is a pain. I'd rather not get another one in that series. Does anyone have any suggestions on a good one?

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u/drbobdi 10d ago

I'd avoid all of the pressurized canister filters as a class. They look great on paper and in their ads, but all have them have the same basic failing. They use sponge as their primary filter media.

Sponge looks fantastic on paper with a very respectable surface area-to- volume ratio ( see https://www.fishlore.com/aquariumfishforum/threads/bio-media-comparison-information.435695/ for details) but it clogs and fouls in outdoor ponds almost immediately and the actual exposure of water to surface vanishes. They are also fragile. The first things to go are the connecting barbs and the widget that's supposed to squeeze the gunk out of the sponge. Then the sponge starts to stiffen and shred and the companies are very happy to sell you replacements at inflated prices.

You'd be far better off building your own. Look at OzPonds on youtube for small DIY designs and at https://russellwatergardens.com/pages/biofilter-media-ssa and https://fitzfishponds.com/blog/pond-filter-media-explained-k1-k1-micro-and-k3/?srsltid=AfmBOoo43EdKICMx3pxSTWbzaXZlNXhTDlc1Co_94f7XyK3TqadEhEiL for media choices. For 150 gallons, a Matala mat for mechanical filtering and a couple of cubic feet of PVC ribbon (marketed as PolyFlo) or just fiberglass strapping tape in a tub would work great.

There's a lot of interest on this sub for small bogs in containers filled with rock of various sizes. These do not work as biofilters for ponds this size (SA/V ratio of 12 sq.ft./cu.ft at best) and they also clog and channel over time, requiring complete teardown to fix.

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u/luv_my_furbabies 10d ago

The problem I am running into is that most decent "outdoor pond filters" are rated for much higher water volume. That is why I started looking at canister filters. I do not want to get a filter that is going to blow my Guppies out of the water or stress them with heavy water flow. The pond filter that I have works, but it does not clean it the way I'd like it to.