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Thread: Pond upgrade. Help!!
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26-01-2021, 10:23 PM #1
Pond upgrade. Help!!
Hi everyone. Fairly new to the forum joined a few months ago and went through tons of posts. Learned a lot already indeed but now looking for some help.
I have a pear shaped sunken pond that is at least 20 years old. By the looks of things it seems that whoever built it just dug a 2 foot deep hole and lined it with rubber liner and stuck some rocks on the edges with mortar. The liner is damaged in places now and I had a job patching all the holes last summer so now looking to upgrade. I still want to keep the shape but make it deeper. I am not looking to keep large koi. Only mainly goldfish and 2 small garden centre koi I already have that don't seem to want to grow very much even in the heated grow on tank in the garage at the moment. The current size is 3.5x2x0.6m in maximum dimensions. The following are my aims and problems:
1. I have one foot deep shelves on 3 sides of the pond. The remaining side is very close to a 4 storey high conifer that has now been removed so I don't fancy digging anywhere near there. Am I ok to use the shelves as support, dig a trench under the existing rocks after removing them and fill with concrete? I can then do a few courses of bricks to bring the level to the undug side. Would this work?
2. The pond used to be 4meters from the house but we have now built a conservatory up to a foot from the edge of the pond. Is there anything I need to be wary of when I dig the collar?
3. I would ideally want to fit a simple bottom drain in the process. Do I need to concrete it in the ground or does this not matter in a liner pond? I assume I will need to dig for the bottom drain pipes before I fill the trench with concrete?
4. As it is sunken, I will be going for pump fed set up. I now have a pressure filter but aiming to get something better for the future but it will have to do for now. Where would I need to fit the pump in this arrangement bearing in mind future upgrades?
Apologies for the extra long post but hoping for as much help as I can. I am hoping to do this job alone and I am an average DIYer so would appreciate a few minutes of anyone's time to answer my queries.
Many thanks in advance.
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27-01-2021, 11:57 AM #2
I have been looking at other forums as well with liner pond construction. Would it be better to dig the whole think to the desired size and depth (thinking perhaps 4 foot deep) and then use H section blocks in the perimeter and fill with concrete? What do people think? And also do I need to pour a concrete slab on the bottom? I am thinking of starting work once the weather is less harsh.
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27-01-2021, 11:22 PM #3
Definitely start when the weather is less harsh is my first comment! But then I would as I've had no end of grief digging a pool last January / February when it did nothing but rain and this year had flooding to deal with!
It's not necessary to put a concrete slab in the bottom of a liner pond, so you could as you say just dig a concrete collar under where the rocks are currently and then build up to the desired height from there.
I don't think you need to be too concerned about the vicinity of the conservatory, it obviously wasn't a concern when the conservatory was added, which I think would be more of an issue.
Bottom drain is a must in my opinion, so yes, dig a hole for it in the bottom along with a trench for the pipework to come out of the pond and to your filter location. I think if you're pouring a concrete slab, it's best to hold the pipe and bottom drain in place with concrete around the bottom drain and also in a couple of spots along the pipes length. Without a concrete slab, I would think it best to apply the same principle and then backfill around the pipe rather than completely encompassing the pipe in concrete. Make sure you dig below the bottom drain to get a good amount of concrete underneath it to support it, so that the lowest part of the drain has plenty of support.
Once you put the bottom drain in, you wouldn't be forced to be pump fed when you are sunken, you can go gravity. I have done exactly this, but you will need to lower your filter room to suit the finished water level after you build up and obviously allow enough height for your filter. You can always dig the filter pit location into the ground also to achieve a gravity setup should you wish. Gravity feed will be better for dirt removal.
You can only really do the gravity feed with the bottom drain, so that's your first consideration in my view.
How high are you thinking of building out of the ground?
Hope the above helps. I'm no expert, so the above is only my opinion, but hopefully useful.
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27-01-2021, 11:50 PM #4
Thank you so much and definitely yes your ideas are very helpful. The pond will still be sunken so only just above ground level. This way we could enjoy the fish from anywhere in the conservatory. I Would not be able to dig for the filter because of a nearby manhole and big roots from old conifers but I thought I could only dig for a barrel that would work as a sump perhaps with a sieve and then keep a submersible pump inside to pump to the filter. This way I could filter the big stuff without worrying about the propeller liquidising it.
Assuming the worst and the conservatory company was not careful enough with the location design (or indeed they would not have thought I would be digging the pond deeper that close), how close can I realistically get to the foundations without causing problems? Are there any rules with the building regs? I am asking as I am considering to slope the floor from shallow to deep close to conservatory and site the bottom drain in the deeper end. This way the pipe run would be minimal.
Again any views would be much appreciated.
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28-01-2021, 11:00 AM #5
So long as the builder was a bona fide contractor I wouldnt be too worried about the foundations they should be ""suitable and sufficient""
therefore any excavation you do with a shovel outside of the building footprint isnt really going to have much effect so long as you stay outside the footprint and not excavate "under" the conservatory footing.1000 gal
2 x Hozelock 6000ltr 9W UV
Allpond Spin Filter 8000 11W UV
Blagdon pond oxy 640 ltr/hr
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Gnmm Thanked / Liked this Post
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28-01-2021, 01:24 PM #6
Apologies about all the questions. I want to do this right first time.
In order to keep the liner hidden, I intend to place one row of rocks around the perimeter, loop the liner on the outside then over and then stack the coping on top. This will mean that the bottom row will be in the water. Is there anything I need to be mindful of apart from sharp edges and leeching rocks? How can I stick the rocks to the liner and to each other besides mortar?Last edited by Gnmm; 28-01-2021 at 01:45 PM.
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28-01-2021, 03:16 PM #7
There are fish safe silicons I have used them in the past in my tropical tanks for sealing and holding structures together
However I am sure many on here have advice on pond safe materials as silicon may not be strong enough in this scenario.
Sounds a suitable way ie overlap as I have done this on my wildlife pond but used "flat" rocks so balanced, no need to use mortars or similar, I found frogs in the crevices and layers when I did some maintenance cutting back pond plants and runners that were within the structure .
DSCF0057.JPG1000 gal
2 x Hozelock 6000ltr 9W UV
Allpond Spin Filter 8000 11W UV
Blagdon pond oxy 640 ltr/hr
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28-01-2021, 03:32 PM #8
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Gnmm Thanked / Liked this Post
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28-01-2021, 07:39 PM #9
This has been very helpful thabk you.
I was just wondering how thick the collar should be? I estimate the pond will be about 5000-7000L. How can I calculate how much cement and sand to order?
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28-01-2021, 09:47 PM #10
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28-01-2021, 09:58 PM #11
What shape is the pond? If it's a regular shape like round square or oblong you can easily work out the volume the collar takes up by measuring the pond volume then if your collar is say 300 mm then just add that measurement to the pond measurements then subtract the pond volume from that volume.
Once you've got the volume of your collar if you speak to a builders merchants they should be able to tell you how much sand and cement you'll need.
There are or were some builders on here that should be able to tell you how much you need too.
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28-01-2021, 10:00 PM #12
BTW 300 mm was just a token figure not a suggestion OK
Again speak to a builder to get the correct sizes for your collar
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28-01-2021, 10:19 PM #13Freddyboy the legend
"we are water keepers first"
Johnathan
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Frimley Koi keeper, Wain Thanked / Liked this Post
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28-01-2021, 10:28 PM #14
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28-01-2021, 10:30 PM #15
When the local dealer says he gunna give ya cement boots he bloody means it. Pay the man
Sent from my F5121 using TapatalkFreddyboy the legend
"we are water keepers first"
Johnathan
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Frimley Koi keeper, Wain Thanked / Liked this Post
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28-01-2021, 10:33 PM #16
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28-01-2021, 10:37 PM #17
Koi dealers are calm and ful of peace watching the fish all day. Shame the hobbyist cant seem to do that without thinking did the fish flash or thats not right what's up with that
Sent from my F5121 using TapatalkFreddyboy the legend
"we are water keepers first"
Johnathan
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Frimley Koi keeper, Wain Thanked / Liked this Post
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28-01-2021, 10:54 PM #18
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28-01-2021, 10:56 PM #19
No need for language like that this is a family forum frim wash your mouth out. Am washing mine with red wine
Sent from my F5121 using TapatalkFreddyboy the legend
"we are water keepers first"
Johnathan
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Frimley Koi keeper, Wain Thanked / Liked this Post
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28-01-2021, 11:19 PM #20
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Best plants to remove Nitrate
pug has a very impressive veg filter on his pond, have a look at some of his his youtube videos....