Pond Liner Advice

[jims-terrano]

Hi guys another none vehicle topic for you. I’m planning a pond in my garden. It’s not going to be a freestyle type shape but more of a formal rectangle that will be partly raised above ground level and partly below ground level probably about 4 foot deep at its deepest with a shelf all the way around.

So my question is how do I work out the size of the liner. I remember back in Ground Force days they advised butile rubber not pvc. Also should I buy proper underlay or just old carpet.

 

[johnb5177]

Jim,
Always Butyl liner, they are the best material. Line the base with damp sand, and if possible the sides/shelves and over the edge.
Old carpet is good, but depending on the size of the pond sourcing that much may be a problem....ask at the carpet shops if their fitters bring back the old stuff, or your local recycling depot.
Always check for sharp edges everywhere, as the pressure of water, even though you don't think it much will push the liner into it and puncture.....remember a cubic metre of water weighs a tonne......
Work out the total square meterage to include base shelves and sides and allow another few feet/centimetres all around.
Fill it slowly and work /fold the liner carefully as necessary as it fills.
Cap the excess edge/lip with turf/slabs to suit. Allow a very shallow shelf/board to allow hedgepigs and other wildlife to escape out......

 

[jims-terrano]

Seen a few websites selling liners with calculators on. Some suppliers offer an alternative liner with a 40 year warranty but it isn’t butyl.
It’ll be raised up approximately 2 feet from surrounding paving and ground level so can’t imagine wildlife getting in.
A butyl Liner is around £200 for size I need so very expensive.

Not doing this project yet as I have other things on the go first so just planning at the moment.

 

[macabethiel]

Pond Liners.

Hi guys another none vehicle topic for you. I’m planning a pond in my garden. It’s not going to be a freestyle type shape but more of a formal rectangle that will be partly raised above ground level and partly below ground level probably about 4 foot deep at its deepest with a shelf all the way around.

So my question is how do I work out the size of the liner. I remember back in Ground Force days they advised butile rubber not pvc. Also should I buy proper underlay or just old carpet.

I am guessing you have made up your mind / cost wise on having a liner. The problem with liners is they are quite easy to puncture via dropping things in, Dogs, Kids etc having a swim and falling in yourself. If you get a leak they are difficult to find & repair.

As your pond is pretty regular in shape have you considered building one with breeze blocks or similar then glass fibre line it using Glass Matt Tissue and Glass fibre gel ?

I have two ponds joined by a curved moat. One was a shop bought shallow Glass Fibre Pond then I built a stream to join it to my big pond that is 5ft 8 inch deep at its deepest and is about 5ft x 7ft being a trapezoid sort of shape. The main pond was made from some free second hand bricks cemented together that I then shuttered with a concrete finish. Exit pipes were built into the smaller GRP pre-formed pond. I joined the stream/moat to this with Glass fibre. Been in place for over 20 years with no leaks!

Only issue I had was the connecting stream/moat would grow loads of weed due to it being quite shallow (15 -18 ") I got round this by slabbing it over so the connection between the two ponds is effectively hidden.

My main cost was the Glass Fibre Resin that I sourced from a wholesaler It was a few years ago but think in total I used about 8 gallons of resin. The stream /moat is about 15 ft long.

 

[macabethiel]

PS

In the early part of the pond build I found that the GRP resin would soak into the concrete and use a lot of the product.

About halfway through the build I started adding PVA to the concrete and painting it on the inside before I lined it with glass fibre tissue & Gel Coat.

 

[jims-terrano]

Now there’s an idea :thumbs not actually thought of that way of constructing the pond. Like I said it’ll be a while before I do anything as I have lots of other things going on too.
I was thinking of the block work due to the terrain and also invasive roots nearby.
My idea was dig a rectangle hole and place two 2x2 paving slabs in the bottom levelled on sand. Then build blocks around the edge of the slabs, maybe two blocks deep. Then smaller slabs on to the top edge of the blocks before building more blocks on the edge of these slabs to form the step. Around this section would be level with my existing patio. Possibly another layer of blocks with stone on the outside of the blocks once above patio level. So deepest rectangle section sort of centre would be around 4 feet deep. I was then going to line with carpet before placing a butyl liner in the pond.

Hope my description makes sense.

There appears to be some cheaper liners out there but you get what you pay for don’t you. That said some appear to be tempting as I can only see us at this house for 10 years but who knows.

 

[macabethiel]

Now there’s an idea :thumbs not actually thought of that way of constructing the pond. Like I said it’ll be a while before I do anything as I have lots of other things going on too.
I was thinking of the block work due to the terrain and also invasive roots nearby.
My idea was dig a rectangle hole and place two 2x2 paving slabs in the bottom levelled on sand. Then build blocks around the edge of the slabs, maybe two blocks deep. Then smaller slabs on to the top edge of the blocks before building more blocks on the edge of these slabs to form the step. Around this section would be level with my existing patio. Possibly another layer of blocks with stone on the outside of the blocks once above patio level. So deepest rectangle section sort of centre would be around 4 feet deep. I was then going to line with carpet before placing a butyl liner in the pond.

Hope my description makes sense.

There appears to be some cheaper liners out there but you get what you pay for don’t you. That said some appear to be tempting as I can only see us at this house for 10 years but who knows.

That's well thought through I would just do a small section at the very bottom that is 5 ft deep if you want to overwinter Koi. They will sleep in the sump during the winter as it's warmer due to temperature inversion when it is really cold!

 

[jims-terrano]

I was thinking 4 feet deep at most, do you think a little deeper for fish to over winter.
Still got to speak to wife, think she’d prefer a large white pond upstairs called a bath. :lol

 

[Terrano Steve]

This place is awesome no matter what the subject is there is always a wealth of experience to draw from :clap

 

[jims-terrano]

This place is awesome no matter what the subject is there is always a wealth of experience to draw from :clap

Long may it last:clap far better than asking questions on Facebook and that’s not aimed at any group in particular just FB as a whole.

 

[macabethiel]

I was thinking 4 feet deep at most, do you think a little deeper for fish to over winter.
Still got to speak to wife, think she’d prefer a large white pond upstairs called a bath. :lol

A 4 ft pond is fine until you get one really bad winter then you wish you had gone down to 6 ft.

 

[jims-terrano]

Fair point.

I’ve approached the subject with Mrs and it appears she isn’t too bothered about me building a pond. Think I might do a few other jobs to pacify her first. I think I could fill my days without having this work malarkey quite easily.

 

[macabethiel]

Fair point.

I’ve approached the subject with Mrs and it appears she isn’t too bothered about me building a pond. Think I might do a few other jobs to pacify her first. I think I could fill my days without having this work malarkey quite easily.

The other aspect of pond building is filtration now that is a challenge if you want to be able to actually see the fish without green water etc.

My filtration is about 85% effective in terms of all year water clarity. I get about three weeks as Spring turns into summer when feeding starts again as the Nitrate levels peak whilst the filter bacteria bacteria multiply to cope with the Nitrite conversion.

After that it is pretty much clear all year as the plants start to grow again for the summer. The bigger your filter capacity the better, mine has a capacity in total of about 300 gallons with the total pond volume being approximately 1,700 gallons. The filter is not really big enough so had to add uV in line filtration.

With the benefit of hindsight wish I had built a natural plant filter as part of the system.

 

[jims-terrano]

Now you have added an extra complication it was at back of my mind that I may add a filter system later and that green water is a given thing with ponds. Kept fish tanks for years but not for a long time now so I understand the mechanics of tank filtration but never really messed with ponds. I’ve seen these big ugly black boxes stuck above water level so assumed that is what it looks like.
So now I need more info and should I now be including a filter system.

 

[johnb5177]

Barley straw cleans up the nitrates, it locks it up. You still need a decent filter/aeration system, but it is a cheap fix.

 

[macabethiel]

Now you have added an extra complication it was at back of my mind that I may add a filter system later and that green water is a given thing with ponds. Kept fish tanks for years but not for a long time now so I understand the mechanics of tank filtration but never really messed with ponds. I’ve seen these big ugly black boxes stuck above water level so assumed that is what it looks like.
So now I need more info and should I now be including a filter system.

My filtration System pumps around 2500 galls per hour that sounds a lot but its about right.
I have a gravity fed brush filter cabinet that is a big plastic water tank, its is the size of two standard square manhole covers. The outlet from the pond side is made from domestic underground toilet waste pipe and connects into the tank. The water tank is divided into two parts the part near the pond connection contains 9 brush filters they are about 18" long & about 8" in diameter. I have a big coarse screen over the pond outlet to prevent fish from being drawn into the filter. The screen is made up from plastic grid sheets cable tied together forming a box that is about a foot square.

The second half of the water tank contains plastic filter medium and the pond pump sits in the bottom like a sump arrangement. The pump outlet is 1.5" Bartol waste pipe mostly push fit. The outlet pipe then runs to the bottom of our garden ( buried underground) where behind our garage so it hidden between the rear boundary wall & the garage wall sits a Concrete Mini Skip that is around 4 ft x 2.5 ft x 2 ft the feed from the pump enters from the inline uV filter & is connected to the bottom of the |Mini Skip. The Mini Skip has a grid base with more filter medium in it. The side of the MIni Skip contains a gravity return to the pond all concealed underground up until it enters the far pond. The Mini Skip I found on an embankment off the A38 part full uf concrete it is made out of a strong Poly-Plastic material with a galvanised steel frame built around the top lip.

I have two diverter valves to restrict the flow so the skip does not overflow due to the slowish gravity return. The Mini Skip is about 4 ft above ground level. A second diverter valve is fitted to the water tank outlet so that the excess pump flow is returned back into the smaller pond. The greater flow is just back into the small pond, the gravity return section from the Mini Skip is a flow of only around 10 galls per minute this is my main Nitrate removal section. Being bottom fed by the pump it can never block up.

When I am back home I will post some pictures - we have a site meeting this Tuesday giving us a firm completion date probably early half of June.

 

[jims-terrano]

That sounds a very complex setup you have, a lot to think about with a pond. Not just a hole in the ground with water in it.

Sounds like good news about your house:thumbs

 

[jims-terrano]

Have been having a look online at filters, a lot seem to pump from pond into filter and then gravity feed back into the pond. Been looking at a Hozelok 10,000 litre with UV integrated but not too sure if that would be enough.

Also what happens to the pump and filter in frosty winter conditions, do you have to keep it running all the time?

 

[macabethiel]

Best to leave some circulation running.

Have been having a look online at filters, a lot seem to pump from pond into filter and then gravity feed back into the pond. Been looking at a Hozelok 10,000 litre with UV integrated but not too sure if that would be enough.

Also what happens to the pump and filter in frosty winter conditions, do you have to keep it running all the time?

The Nitrifying Bacteria mostly die off in the winter as they have little in the way of Nitrites to convert into Nitrate so technically you do not need the filter to run in the winter.

However there are lots of reasons to keep some flow in the winter especially if you have leaves etc falling into the pond. Another advantage is it does reduce the chance of the pond freezing over except in the case of severe winter weather.

On the downside it can lead to colder water than normal as the circulation hampers the temperature inversion process as water approaches freezing point. When we have had really bad winters (2 in the last 20 years for us in Derby) when the ponds both froze over I simply dropped the water level by an inch or so. This left the Ice in place with a film of air between the ice & the moving lower water surface.

I am not a big fan of using Barley Straw or extract due to its altering the water pH pushing it towards the acidic side.

 

[jims-terrano]

Have been watching a few videos on YouTube from a bloke in the north east. He seems to of built a few ponds out of concrete and a couple of coats of render with pond paint over the top.
He’s also spent time talking through filters. One idea he suggested is moving the pump on to a shelf so the deeper sections stay at a stable temperature for over wintering fish.