Hi from Cumbria in England

[Ponderosa]

Hi All - I live in a town in Cumbria in the north of England.
About 6 years ago I installed a small pre-formed pond in the garden - it is about 1.5m by 0.75m wide by 0.5m deep.
It is home to around 10 goldfish (we had a couple of small Koi but birds got them) with quite a few plants. A pump sends water down a (3m long x 0.5m high) stream back into the pond.
This all works nicely and is fairly self sustaining.
Recently we built decking round the pond, so instead of the surface of the pond being at ground level it is now (about) 0.25m below the decking.
I would like to raise the height of the pond to just below the decking but do not want to disturb the preformed pond. I also want to create a better shallow area at one end of the pond.
This is what I am considering:
1. Put sandbags under the decking around the pond and get a flexible pond liner to line the existing pond up and over the sandbags but below the decking.
2. In order to create a better shallow area, I was thinking of using sandbags (?), but should these be in the pond or under the flexible pond liner?

Obviously I should have thought of this before getting the decking built! Any ideas that would help me?

 

[addy1]

Glad you joined!

Using a liner in the preformed would work well, to raise the area you would want the sand bags under the liner not above.

How about lining the pond and leaving it deep, your fish would be happy with the extra water. If you want plants in it (the reason for the shallow area) you can put the plants on crates, overturned pots etc.

 

[DrDave]

Welcome to the Forum!

 

[taherrmann4]

Welcome to the forum.

 

[j.w]

Ponderosa

 

[sissy]

welcome and deeper would be nicer for the fish and probably the water quality like addy says .Putting a liner in a preformed may trap run off water between the 2 and it could balloon the liner up .and could cause freezing between the liner and preformed in the winter

 

[addy1]

welcome and deeper would be nicer for the fish and probably the water quality like addy says .Putting a liner in a preformed may trap run off water between the 2 and it could balloon the liner up .and could cause freezing between the liner and preformed in the winter

didn't think of that sissy. Maybe if have a edge lower around the preform for any water that wanders under the new liner to be directed away from the preform.

 

[taherrmann4]

Or if you aren't ever going to use the preform again just drill some holes in to allow the water to drain.

 

[addy1]

Or if you aren't ever going to use the preform again just drill some holes in to allow the water to drain.

DUH!!!!!!!!!!!!

lamo kiss principle...........

 

[sissy]

tmann if you drill holes in the preform the liner with water in it will plug up those holes because of the pressure of the water .I had a preformed that a mole chewed holes in and had to put a liner on top with water in it that plugged them up and water got between the preform and liner and caused the liner to raise up in spots .It eventually drained out but if winter came not sure what would have happened .Thats why I built the new pond .live and learn and quick fixes usually mean temporary fixes .

 

[addy1]

tmann if you drill holes in the preform the liner with water in it will plug up those holes because of the pressure of the water .I had a preformed that a mole chewed holes in and had to put a liner on top with water in it that plugged them up and water got between the preform and liner and caused the liner to raise up in spots .It eventually drained out but if winter came not sure what would have happened .Thats why I built the new pond .live and learn and quick fixes usually mean temporary fixes .

True sissy, but you could put something between the two that will not let the liner suck into the hole, and let the water seep away.

 

[taherrmann4]

Cut holes in the bottom and then put about an inch or two of gravel on the bottom to keep the holes open or you could put sand in the bottom.

 

[addy1]

Cut holes in the bottom and then put about an inch or two of gravel on the bottom to keep the holes open or you could put sand in the bottom.

Yep! that would work

 

[Ponderosa]

Hello again. I have read all your posts with interest. I haven't started my little project yet cos it is pouring down with rain (sunny August!). Hope to get some time next week.
I take the point about getting water between the liner and the pre-formed, I am hoping that by careful positioning of the lip of the liner I can minimize this problem. Attached is a rough sketch of what I intend (its saved as a jpg - I couldn't find another way of doing it - hope that works)



In answer to some of the comments:

- I agree that removing the preformed would be the ideal option, but unfortunately the decking overhangs it - so I physically could not lift it without taking the decking up.

- I would prefer to avoid putting holes in the preformed in case I ever have to revert to it again.

If I put some fine gravel in the bottom of the preformed, would water accumulate in that and then evaporate as weather conditions allow - or am I being naive?

 

[addy1]

If you drape the liner over the edge of the preform, make sure the edging of your preform and liner are higher than your land, that would keep water from seeping between the two. Make a dirt berm around the preform, so any run off will not run into the preform, you may already have it set up that way. When you lay down your liner make sure you have a good berm under the liner so the liner edge is higher than your land. The other thing to look at is run off, if there is a problem area, make a french drain type set up so the water is pathed around the pond, not under the liner......

does that make sense? if not will try to type in more detail lol