Thread: New natural looking koi pond/ filter house advice

Newbie here!! Hi all, I have been researching for about 2 -3 years and am finally starting to plan my own koi pond build. I want an inground pond with a natural looking finish (rocked top edge level with the garden). I am fairly happy on the pond build itself which will be a liner finish with one bottom drain and a skimmer. One of the returns will come via a water feature built out of rocks. The bit I am struggling with is the filter house/ area. Ideally the submerged filter area needs to go in the corner of my garden which will be offset to the pond which will be a figure of 8 shape. I am planning on using a Nexus 320 for the bottom drain and return into the pond with the skimmer line returning via the water feature probably via a tempest. Any tips on the filter area design please and approx. size? Ideally I want to put a self build shed over the top of the filter area without it being an unsightly backdrop to the pond..... thanks

I've just finished building my first "proper pond". The one big mistake I made was not allowing enough space for all of the plumbing and equipment. I made a covered bunker for the equipment room and allowed myself an internal area of 1.1m x 2.2m. This is way to small, I have 2 bottom drains with 3" pipe and a skimmer with 3" pipe feeding into a small drum filter. With ball valves, no return valves, unions, flush outs, all tack up a lot of space.

I had to compromise my design as I did not have enough space, twice as big would have been about right.

So allocate enough space.

Thanks for the reply Gary and really helpful advice. I am guessing about 2m x 4m should be about right hopefully!! How did the build go - would be helpful to see any pics you have of your filter bunker? Thanks

Originally Posted by JImmaddog

Thanks for the reply Gary and really helpful advice. I am guessing about 2m x 4m should be about right hopefully!! How did the build go - would be helpful to see any pics you have of your filter bunker? Thanks

Hi Jim, Iv got a similar pond build to what your after although still not finished, Iv got a build thread on here.

I’m pretty pleased with mine although one thing I would have done is rethink how to stop groundwater, as mine floods in the winter and I have to sump it out. Not sure how maybe I would have lined it. And then making it bigger would have been my second thing, it’s very tight in there and wish I had a bit more space to move around.

All the best with the build


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Hi there,
I have a very similar pond design to yours and would agree with others that my main regret is not building a bigger filter pit area. Accessing ball valves etc. is a pain in the arse and although I’m only 50 - I worry about how I’m going to reach some of the pipes etc. when I’m older and can’t bend as far. Will probably need to rebuild at some point. Good luck with your project.


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Thanks James - have you got a link for your build? Would love to have a look .......... thanks for the reply mate and helpful advice. Safe to say I need to go big!

Thanks mate - any pics of your build as would love to have a look? Thanks

Originally Posted by JImmaddog

Thanks for the reply Gary and really helpful advice. I am guessing about 2m x 4m should be about right hopefully!! How did the build go - would be helpful to see any pics you have of your filter bunker? Thanks

I will create s video and post it.

In the meantime here is a build thread of it, it is on another site. My pond is a little different as I use a bog filter as the main bio filter, with rdf as a pre-filter

https://www.gardenpondforum.com/thre...started.33181/

Thanks Gary - just had a read. What an amazing project! You must be proud of that mate - how is it running?

Originally Posted by JImmaddog

Thanks Gary - just had a read. What an amazing project! You must be proud of that mate - how is it running?

Thanks for the feedback. It still early days, I filled it last month, when we had the really hot weather and that caused the water to turn into pea soup, at that stag I had no plants in the bog filter. Since then we have planted the bog and it's started to clear the water, the plants are young and small so need time to grow, but it is a lot clearer than it was.

I've had some problems with the drum filter, it was an older Filtreau, it took a bit to balance the flow correctly and all seemed ok, but with pea green water, as can be expected it blocked the screen, which caused excessive flushes using up way to much water. So I have taken out the screen while the water clears and I intend to replace the screen with a larger aperture and higher open area mesh to get faster flow. As I have the large bog area my use of the rdf is slightly different to normal. Fingers crossed it all works okay.

Originally Posted by JImmaddog

Thanks James - have you got a link for your build? Would love to have a look .......... thanks for the reply mate and helpful advice. Safe to say I need to go big!

Here you go mate, still not finished hopefully get round to landscaping and building the waterfall soon as the Mrs kitchen is nearly finished

New Natural look koi pond build
https://r.tapatalk.com/shareLink/top...ink_source=app


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Thanks James - certainly grafted on this one! Any up to date photos of it finished or is it still work in progress? I see what you mean about the filter pit space, definitely the bigger the better and I think rather than hide mine I will try and make a feature out of it and try to disguise the shed I build over the top. Did you source your rocks in the end? I have been looking and they are so expensive!!!! Might try going to my local quarry and see if we can strike a deal Great project mate and thanks for sharing...

Originally Posted by JImmaddog

Thanks James - certainly grafted on this one! Any up to date photos of it finished or is it still work in progress? I see what you mean about the filter pit space, definitely the bigger the better and I think rather than hide mine I will try and make a feature out of it and try to disguise the shed I build over the top. Did you source your rocks in the end? I have been looking and they are so expensive!!!! Might try going to my local quarry and see if we can strike a deal Great project mate and thanks for sharing...

Cheers Jim, no still not finished as the Mrs shoehorned an extension in. Going to get back on it in a few months. The ponds running great so far, could have done with some more returns to keep the flow on the bottom more moving waste to the drain.

I’m going to put some electric struts on the filter decking roof and deck the area so it’s hidden under ground. Absolute ball ache getting it open at the moment as it’s so heavy.

Rocks wise so far just free welsh slate rocks from Facebook marketplace worth a look, Iv started to mock up a waterfall but not there yet. I just put a notification in for rocks and everytime they are added I check to see anything worth picking up. Got some giant free ones for the waterfall but god knows how I’m going to get them in position. Think Iv spent £50 so far and got around half the amount needed so worth a look. Got a guy at a local quarry too il going to put an order in when I can afford as I can give him more precise measurements needed etc.


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Nice - good luck mate and will create a thread when I actually break ground (keep putting this off as then there is no returning )

I was undecided around a drum filter but your thread has convinced me so need to add that into the mix now as well!!!

Originally Posted by JImmaddog

Nice - good luck mate and will create a thread when I actually break ground (keep putting this off as then there is no returning )

I was undecided around a drum filter but your thread has convinced me so need to add that into the mix now as well!!!

Good luck with it Jim, a mini digger may be a better idea I lost 2 stone but it took ages. I would 100% recommend a drum unless you have loads of free time to be cleaning filters etc. although I have a cam on the pond and check it 30 times a day lol


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Thanks mate - sorry been away. Digger is definitely top of my list although you tube is doing my head in as I keep thinking about a bog filter now! For everyone that says they are great there are 10 who say not! Think drum is the way.......

Originally Posted by JImmaddog

Thanks mate - sorry been away. Digger is definitely top of my list although you tube is doing my head in as I keep thinking about a bog filter now! For everyone that says they are great there are 10 who say not! Think drum is the way.......

Yeah I think it all depends on what works for you and your lifestyle. My filtreau drum has been great up till now but it’s going to need some maintenance in the future and god knows how to change parts. Nexus seem like a nice sweet spot and come with auto cleaning add ons and from what I can see more reliable long term. Lots of research and working out what’s for you mate


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