New Pond build - London, UK - Tips Please


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Hi guys,

I started a DIY pond build last month, dug by hand. I literally just thought it was a hole, water and fish, and didn't know anything about ponds etc. I think it's easy to see a hotel pond etc and just think it's easy and not understand the work that goes into maintaining the water quality etc.

So, after "finishing" it two times and then draining, moving the fish etc for renovations, I have learnt a lot and I am on my third and final "renovation" in the past month. I have 3 7" Koi and 15 3-4" Koi in a large inflatable pool with aeration/shade etc. My biggest problem was the water level because the ground already wasn't level but I've now built the sides up quite a lot with dirt I've dug out. I've got shelves round the inside for rock work and to cover the liner. We live just outside London, in a built up area with houses either side and behind, and I didn't take any notice of the "Heron tips" because I've never seen one before. The damn thing came by last week and took some little ones out, about 10-15 but solved my future over-stocking problem!

I have a waterfall cascade box filter which is going to run the waterfall via an Oase Aquaskim 40 skimmer and pump. And I have a separate pump running into a large Kockney Koi black box filter with UV. I have no bottom drain. Despite how strongly some "Koi" guys recommend one and "a pond isn't a pond without one", I just can't do it myself, I don't want the extra work and I'd have to hire someone to do it.

Now, one of my big questions, I'd like to put some small rocks and pebbles to cover the liner at the bottom but you read so much on Koiphen on why not to do it. I'm quite happy to drain the pond once a year, wash down the rocks and then re-fill if necessary. It really doesn't seem like such a big job. I've already drained it twice. How much "muck" and "poisonous gases" which "will kill your fish, if not now, in a couple of years" is going to accumulate? It's a case of a the pebbles/gravel/small stones and a once year clean out vs bare liner and vacuuming the bottom although I am unsure how often this would be needed? What would you guys say? I'm going to have some plants in gravel pots around the edges and the Koi won't be able to get to them because they'll be lodged in between rock rock.

The pond is an oval/kidney shape and will be about 3ft in it's deepest part. There are different depths. On average a conservative estimate is about 2000 imperial gallons / 2400 US gallons. I'm really not bothered whether it's a "koi pond" "water-garden" whatever, I just want a nice backyard pond with rockwork, clear water, some plants on the edges and healthy Koi. I'm not going to go crazy with feeding and I don't intend to be some sort of high end Koi keeper!

Thanks!
 

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Meyer Jordan

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As long as the gravel layer covering the liner on the bottom of the pond does not exceed 2 inches (50mm) there are no negative effects. In fact thiss actually provides enormous benefit to the pond's ecosystem
 
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As long as the gravel layer covering the liner on the bottom of the pond does not exceed 2 inches (50mm) there are no negative effects. In fact this actually provides enormous benefit to the pond's ecosystem

Thanks. Appreciate this has been asked many times. The guys on the Koi forum would have you believe it's literally the worst thing you can do. I wasn't planning on layering the gravel. I was just thinking a thin layer of gravel and some bigger pebbles spread around.

Do you recommend draining it yearly or letting it be for longer? There doesn't seem to be concrete evidence but the arguments always seem to be stronger on the "don't have it" side. I'm really not that bothered all together but I'd rather have plants/rocks than bare liner but I just want to make sure the Koi don't end up sick or have problems down the line.
 

sissy

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Thing is as the koi get older the stress on them by catching and moving them increases and then you are also starting over with new water and waiting for everything to even out .Is it worth it no .I love my fish to put them through all of that .Plus the work involved is a big concern ,we are not getting any younger
 

Meyer Jordan

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Thanks. Appreciate this has been asked many times. The guys on the Koi forum would have you believe it's literally the worst thing you can do. I wasn't planning on layering the gravel. I was just thinking a thin layer of gravel and some bigger pebbles spread around.

Do you recommend draining it yearly or letting it be for longer? There doesn't seem to be concrete evidence but the arguments always seem to be stronger on the "don't have it" side. I'm really not that bothered all together but I'd rather have plants/rocks than bare liner but I just want to make sure the Koi don't end up sick or have problems down the line.

Well, let's explore what really happens when a thin gravel layer is added to the bottom of a pond-

-Additional surface area is provided for the establishment of biofilm and periphyton (the backbone of a healthy system). This translates into more Nitrifying bacteria resulting in better overall water quality and oxygenation (the pond is its own primary biofilter).
-The void space between the individual pieces of gravel provide micro-habitats for a myriad of micro- and meio-organisms, thus increasing the diversity of the pond's food chain.
-In a pond that has Koi it provides a means for them to feed naturally by rooting around (they are, by nature, bottom feeders).
-By increasing the diversity of micro- and meio-organisms, natural predation on organic pathogens and parasites is also increased.

Through earnest attention to fish load, amount of food, control of any externally generated organic debris, proper supplemental biofiltration, and adequate flow rate (all required on any pond) the pond may not require cleaning for years.
 

sissy

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And a lot of work to get to that point every time you clean the pond .Plus if you have city water even more work .That is why i pump my pond water into takes to store it on every rebuild of my pond and even then t s not an easy job .But when it does need cleaning then you are not only older but so are the fish and that means they are a lot bigger .
 
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Welcome Geo :) Your pond looks very nice! I used to have gravel in the bottom of my pond, but a lot of it shifted ( I'm sure the koi helped ! ) to the deepest area of the pond, which deprived the koi of the lowest depth for winter. I also grew water lilies bare root in the gravel and they went crazy !

I liked the look of the gravel, but it was a pretty big mess when it was removed, so I'm happier without it.
 
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Gravel bottoms are the single most controversial subject in the ponding world, followed closely by bottom drains. You've heard on the koi forums that you cannot keep koi in a rocked pond without a bottom drain. You'll meet people here who are doing exactly that. So welcome to the Dark Side. haha! I have a rocked pond with koi and goldfish - no mechanical filter. The koi people would just say "well your fish haven't died YET... but they will". Ooooookay! Eventually, yes, they will. Of old age.

@Meyer Jordan shared lots of great things that gravel will do for your pond and fish. Let me add one more reason for adding gravel to your pond - try walking on a bare liner pond vs a pond with a gravel bottom. Much, much safer and easier to have some gravel under foot. Honestly I don't care one way or another what other people do - I just like to share the truth of a rock and gravel pond. It's easy to care for - at the end of our sixth summer, we've never done a clean out and don't have any plans to do one any time soon. We love our rocked pond!
 
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I just listened to a podcast by the Pond Hunter Mike Gannon discussing gravel in a pond. I think it was episode #21. Good information.
 
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Thanks guys.

Ideally i'd like not to have to clean out the gravel/rocks for at least a few years and if the water parameters are good then I wonder exactly when the time is you'd decide to do a clean to remove "all those toxic gases that will kill your fish".

I'm just trying to figure out if the argument is really superficial i.e it doesn't really matter. I'm only going to be feeding lightly i.e once a day max in spring/summer and not too much. I am guessing on a bare liner things will also accumulate. I'm not interested in growing Koi to maximum sizes/weights. The liner will get covered with Algae anyway. Rocks would look nicer. I've just got to decide if there really is a filtration benefit and no downsides apart from potential cleaning.
 
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Thanks, it's on iTunes; I kind of forgot that existed, HaHa.

I do wish people would shorten up their podcasts - under 30 minutes would be better than an hour and 15. It's just too big of a time commitment!
 
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Thanks guys.

Ideally i'd like not to have to clean out the gravel/rocks for at least a few years and if the water parameters are good then I wonder exactly when the time is you'd decide to do a clean to remove "all those toxic gases that will kill your fish".

I'm just trying to figure out if the argument is really superficial i.e it doesn't really matter. I'm only going to be feeding lightly i.e once a day max in spring/summer and not too much. I am guessing on a bare liner things will also accumulate. I'm not interested in growing Koi to maximum sizes/weights. The liner will get covered with Algae anyway. Rocks would look nicer. I've just got to decide if there really is a filtration benefit and no downsides apart from potential cleaning.

I do think there are filtration benefits to having gravel and it is easier to walk on. I think if you keep your lilies potted and make sure the gravel doesn't slip and fill in the deeper areas of your pond, you'll be fine :)
 

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