Discussion:
Wildlife Pond
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Chris J Dixon
2021-09-13 10:33:39 UTC
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I am considering replacing my existing water feature, a drilled
slate monolith on a pebble pool

<https://www.primrose.co.uk/90l-finia-reservoir-for-water-features-indooroutdoor-use-p-56699.html>

with a wildlife pond, probably around 1 m x 2 m and about 600 cm
deep in the middle.

Reading up, it seems that using a butyl liner is more appropriate
than preformed pools for this purpose, as the shelving and ramp
can be much better tailored. Not sure what the best edging would
be.

I still want to re-use the drilled monolith, which is a piece of
slate about 600 mm high, and must weigh close to 80 kg, far
beyond my lifting capacity. I moved it into place by "walking" it
along.

I am unsure how to support it in a stable position in the new
pool, and feed the pump hose up the vertically drilled bore.

I have seen suggestions of placing concrete, or presumably a
paving slab, beneath the liner and fleece, then building inside
the liner upon this solid base.

Since liner installation seems to involve filling it
progressively with water, I guess I would then have to empty it
again to build anything inside.

I reckon getting the monolith into position would then involve
some temporary works akin to pyramid building.

Maybe the pipework would be easier if I managed to cut a slot in
the monolith base and introduced a pipe bend of some form.
However, that would require the heavy slate to be laid down, and
I also need to avoid unwanted splits in the stone.

I welcome any thoughts and advice on all aspects of the project.

Sorry if it sounds like rambling, but it helps me to get my own
head round things.

Chris
--
Chris J Dixon Nottingham UK
***@cdixon.me.uk @ChrisJDixon1

Plant amazing Acers.
newshound
2021-09-13 11:09:11 UTC
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Post by Chris J Dixon
I am considering replacing my existing water feature, a drilled
slate monolith on a pebble pool
<https://www.primrose.co.uk/90l-finia-reservoir-for-water-features-indooroutdoor-use-p-56699.html>
with a wildlife pond, probably around 1 m x 2 m and about 600 cm
deep in the middle.
Reading up, it seems that using a butyl liner is more appropriate
than preformed pools for this purpose, as the shelving and ramp
can be much better tailored. Not sure what the best edging would
be.
I still want to re-use the drilled monolith, which is a piece of
slate about 600 mm high, and must weigh close to 80 kg, far
beyond my lifting capacity. I moved it into place by "walking" it
along.
I am unsure how to support it in a stable position in the new
pool, and feed the pump hose up the vertically drilled bore.
I have seen suggestions of placing concrete, or presumably a
paving slab, beneath the liner and fleece, then building inside
the liner upon this solid base.
Since liner installation seems to involve filling it
progressively with water, I guess I would then have to empty it
again to build anything inside.
I reckon getting the monolith into position would then involve
some temporary works akin to pyramid building.
Maybe the pipework would be easier if I managed to cut a slot in
the monolith base and introduced a pipe bend of some form.
However, that would require the heavy slate to be laid down, and
I also need to avoid unwanted splits in the stone.
I welcome any thoughts and advice on all aspects of the project.
Sorry if it sounds like rambling, but it helps me to get my own
head round things.
Chris
I think you need to need to get your basic pool sorted with butyl liner,
ledges, etc. first. Filled, and allowed to settle. I guess you are
thinking to use the feature as something like an "island" in the middle.
You say it is 600 mm high, so its "end" must be about 50 square
centimetres. The problem you are going to have is to prevent your
"engineering" structures from cutting into the butyl liner. Also, you
have to decide what materials to use that will be compatible with a
wildlife pool. Stainless steel is probably an obvious choice, but IIRC
fully galvanised steel will acquire a biofilm that will prevent
excessive corrosion and leaching of zinc.

So, as a starter for 10, how about a stainless steel disk say 5-6mm
thick and 50cm diameter (for strength and stability), with suitable
upstands forming a socket for the "monolith". Then, on the bottom of
this for compliance and to avoid a cutting edge, a 10 cm larger disk of
(say) 18mm solid rubber sheet (or perhaps EVA foam matting). I think you
will need to engineer a side entry for your water supply, keeping the
supply at the bottom sounds like asking for trouble. To install it,
three strong blokes with a length of scaffolding bar or suitable floor
joist, suspending it with rope or nylon webbing like a gantry crane.
(Easy enough lift for two guys resting it on their shoulders, with the
third to help with adjustments). Lifting on the monolith, not the
stainless, for stability so the base will need to be tight on the monolith.
Chris J Dixon
2021-09-14 14:20:34 UTC
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Post by newshound
Post by Chris J Dixon
I am considering replacing my existing water feature, a drilled
slate monolith on a pebble pool with a wildlife pond,
I think you need to need to get your basic pool sorted with butyl liner,
ledges, etc. first. Filled, and allowed to settle. I guess you are
thinking to use the feature as something like an "island" in the middle.
You say it is 600 mm high, so its "end" must be about 50 square
centimetres.
The base has four sides. 200 mm and 250 mm approximately
perpendicular, with 350 mm and 150 mm angled joining them. So, I
reckon somewhere nearer 500 sq cm.
Post by newshound
The problem you are going to have is to prevent your
"engineering" structures from cutting into the butyl liner. Also, you
have to decide what materials to use that will be compatible with a
wildlife pool. Stainless steel is probably an obvious choice, but IIRC
fully galvanised steel will acquire a biofilm that will prevent
excessive corrosion and leaching of zinc.
I wonder if some form of heavy duty plastic construction, re
purposed from I know not what, might suffice?
Post by newshound
To install it,
three strong blokes with a length of scaffolding bar or suitable floor
joist, suspending it with rope or nylon webbing like a gantry crane.
I'm not at all sure that I have such a resource to hand.

Chris
--
Chris J Dixon Nottingham UK
***@cdixon.me.uk @ChrisJDixon1

Plant amazing Acers.
newshound
2021-09-14 17:47:58 UTC
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Post by Chris J Dixon
Post by newshound
Post by Chris J Dixon
I am considering replacing my existing water feature, a drilled
slate monolith on a pebble pool with a wildlife pond,
I think you need to need to get your basic pool sorted with butyl liner,
ledges, etc. first. Filled, and allowed to settle. I guess you are
thinking to use the feature as something like an "island" in the middle.
You say it is 600 mm high, so its "end" must be about 50 square
centimetres.
The base has four sides. 200 mm and 250 mm approximately
perpendicular, with 350 mm and 150 mm angled joining them. So, I
reckon somewhere nearer 500 sq cm.
OK, I don't really understand your "monolith" then. I was assuming it
was something like the monolith in the film 2001, solid and 60cm high,
the base area following from the density of slate.
Post by Chris J Dixon
Post by newshound
The problem you are going to have is to prevent your
"engineering" structures from cutting into the butyl liner. Also, you
have to decide what materials to use that will be compatible with a
wildlife pool. Stainless steel is probably an obvious choice, but IIRC
fully galvanised steel will acquire a biofilm that will prevent
excessive corrosion and leaching of zinc.
I wonder if some form of heavy duty plastic construction, re
purposed from I know not what, might suffice?
Yes, heavy duty plastic should be OK to protect the liner, if you can
get it in a suitable shape.
Post by Chris J Dixon
Post by newshound
To install it,
three strong blokes with a length of scaffolding bar or suitable floor
joist, suspending it with rope or nylon webbing like a gantry crane.
I'm not at all sure that I have such a resource to hand.
I have grown up children. Are you digging the hole yourself? If so, you
might only need one other. If not, a pair of labourer / gardner types
could do it.

I suppose another approach might be to dig your pond with a roughly
spherical depression in the middle, put in the liner, then cast a
sand-cement "footing" in the middle and bed your monolith in that,
allowing it to set for a week before adding water. I'd still worry about
any sharp edges from the monolith damaging the liner while you placed
it. You would presumably need a few water changes to remove alkali
leaching from the cement.
Post by Chris J Dixon
Chris
Chris J Dixon
2021-09-14 19:19:28 UTC
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Post by newshound
Post by Chris J Dixon
Post by newshound
I guess you are
thinking to use the feature as something like an "island" in the middle.
You say it is 600 mm high, so its "end" must be about 50 square
centimetres.
The base has four sides. 200 mm and 250 mm approximately
perpendicular, with 350 mm and 150 mm angled joining them. So, I
reckon somewhere nearer 500 sq cm.
OK, I don't really understand your "monolith" then. I was assuming it
was something like the monolith in the film 2001, solid and 60cm high,
the base area following from the density of slate.
Are you sure you didn't drop a zero?

Here are a couple of shots immediately after installation, before
the planting around it matured.

<https://www.flickr.com/photos/chris_j_d/albums/72157719846136489>

Chris
--
Chris J Dixon Nottingham UK
***@cdixon.me.uk @ChrisJDixon1

Plant amazing Acers.
Vir Campestris
2021-09-14 20:20:03 UTC
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Post by Chris J Dixon
I am considering replacing my existing water feature, a drilled
slate monolith on a pebble pool
<https://www.primrose.co.uk/90l-finia-reservoir-for-water-features-indooroutdoor-use-p-56699.html>
with a wildlife pond, probably around 1 m x 2 m and about 600 cm
deep in the middle.
<snip>

Assuming you do mean 600mm / 60cm deep - that's not very deep.

Ours is about that. 2 feet or so.

A few years down the line and it's got a few inches of silt / sludge in
the bottom, which is full of life.

When the weather is dry the level drops quite a bit, not helped by a
couple of punctures near the edge.

By the time evaporation has dropped the top of the water by 30cm, and
the bottom has come up by 15cm, there's only 15cm of water left :(

I've been advised we ought to have a couple of meters depth, and
re-digging it is on the list of things to do one day. It'll be better
for the four species of amphibian that breed in it.

There's been a pond in our garden since at least 1855 according to
maps.nls.uk so they've had time to find it ;)

Andy
Chris J Dixon
2021-09-15 06:32:55 UTC
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Post by Vir Campestris
Post by Chris J Dixon
I am considering replacing my existing water feature, a drilled
slate monolith on a pebble pool
with a wildlife pond, probably around 1 m x 2 m and about 600 cm
deep in the middle.
<snip>
Assuming you do mean 600mm / 60cm deep - that's not very deep.
Ours is about that. 2 feet or so.
My conversion shows 2 feet as 609.6 mm, so not really different?
Post by Vir Campestris
I've been advised we ought to have a couple of meters depth, and
re-digging it is on the list of things to do one day. It'll be better
for the four species of amphibian that breed in it.
I'll need to consider that, but it would make it a significantly
greater task to excavate.
Post by Vir Campestris
Andy
--
Chris J Dixon Nottingham UK
***@cdixon.me.uk @ChrisJDixon1

Plant amazing Acers.
Chris J Dixon
2021-09-15 08:29:15 UTC
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Post by Chris J Dixon
Post by Vir Campestris
Assuming you do mean 600mm / 60cm deep - that's not very deep.
Ours is about that. 2 feet or so.
My conversion shows 2 feet as 609.6 mm, so not really different?
Sorry. When I read your posting properly, I see you were agreeing
with me. My mistake.

Chris
--
Chris J Dixon Nottingham UK
***@cdixon.me.uk @ChrisJDixon1

Plant amazing Acers.
AnthonyL
2021-09-15 11:37:41 UTC
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On Tue, 14 Sep 2021 21:20:03 +0100, Vir Campestris
Post by Vir Campestris
Assuming you do mean 600mm / 60cm deep - that's not very deep.
Ours is about that. 2 feet or so.
A few years down the line and it's got a few inches of silt / sludge in
the bottom, which is full of life.
When the weather is dry the level drops quite a bit, not helped by a
couple of punctures near the edge.
By the time evaporation has dropped the top of the water by 30cm, and
the bottom has come up by 15cm, there's only 15cm of water left :(
I've been advised we ought to have a couple of meters depth, and
re-digging it is on the list of things to do one day. It'll be better
for the four species of amphibian that breed in it.
There's been a pond in our garden since at least 1855 according to
maps.nls.uk so they've had time to find it ;)
I'm fairly new to ponds and have a small one on the rockery which is
probably 2' deep at the most. The past two years the pond has become
rancid and I've ended up emptying it, cleaning and refilling from the
water butt.

The sludge at the bottom also has much life and I despair that this is
going out with the wash. I assume there are such things as damselfly
larvae in amongst it. Not seen backswimmers now for two seasons. Yet
a frog seems to be happy in there.

I wonder how best to fix the issue, or at least preserve some life.
Maybe I'm not clearing the bottom of the pond early enough in the
season and this summer has been very dry. Overhanging walnut tree so
there are walnuts rotting. I don't have fish and only a small solar
pump/fountain.

The water butt allows me to keep the pond from getting too low and I
try to avoid tap water. The water from the butt seems clean.
--
AnthonyL

Why ever wait to finish a job before starting the next?
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