Need to Add height to a preformed Pond Shell


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I have a problem with my very large preformed pond shell. its a fibreglass construction with a rubber top coat.
I didnt realise until I filled it, that its not completely level.
It was a real pain to install as its quite inaccessible and about 3mtrs x 1.5 mtrs wide.
I took alot of care to make sure there were no voids under it, and dont want to spend another 2 days re-installing it again.
Would it be practical to modify the height of the shell on the low end ?
Im thinking of gluing some flexible tubing along the top lip to increase the height and then hiding it under some stone edging.

Anyone done anything similar ?
Thanks for reading !
Sauce
 
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Physically raising the low end
Edit : Sorry, I dont mean lifting the low end higher, I want to cheat and add a height extension to one end. Does that make sense ?
 

Meyer Jordan

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That can be done, but doing so will create a void under the section of the pond that is now at the low end. This may or may not encourage cracking at a future date.
 

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No, I believe Sauce is talking about adding the extension on the top edge of the side that is low without messing with the bottom at all.
 
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sissy

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The risk is of it leaking through the height extension .How long will it hold and how well it will hold up over time.Preforms will raise and lower during changes in weather also .Plus over time they will compact the soil over time with the weight of the water.Meaning that it may level by it's own weight or may even get worse .The you never know .
 

Meyer Jordan

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As @sissy styated, it is very risky attempting to add any form of height extension. It will invariably leak. Better to take the time to re-level this pond.
 

addy1

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Welcome to our group! I would try to re-level it. It is hard to add height without it leaking.
 
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Sigh, I was afraid that would be the consensus.
Ive started draining it and am going to re-level it tomorrow. Will post photos for the curious.
Its a new Pond install I designed from scratch and has been sitting fallow for nearly a year, just filled with stale water going rancid and growing mossies. Over the months i had a old pump moving the water to prevent larvae from growing, and had a few small hardy mossie fish from the LFS. The guilt over the poor water quality for the 3 fish in there at the moment has drivin me to finally finish the fit out. Ill start a Pond construction thread me thinks.

Thanks guys !
 

addy1

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I put rock dust, ground up rocks, under my tanks, it packs hard and has kept them level. Sand also works, make a layer wet it down and pack it. I boot stomped mine on top of a piece of wood until it was packed.

So far, around 4 yrs later, they are still staying level.
 
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addy1

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Sounds good, its actually all surrounded by sand, living in Western Australia, dry desert sand is what passes for soil.
Aww got it! We have shale, dirt, clay, rocks................

Do your best to make a firm bottom for the tub to set on. We have freeze heaving, so far the rock dust has kept the tanks stable.

Mine is partly buried, partly not, they are on a serious slope, upside level with the ground downside naked except what dirt I piled up. The tanks are 2.5 feet deep.
 

sissy

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I talked to a pond builder and since you have sand but not sure you can get hold of it you can use the sand with the hardening additive to it .The kind you use for laying patios .The additive can be bought alone and your own sand added polymeric sand additive.Reason I talked to him last week is because I want to put a preformed I got cheap back in for plants and I did not want the problems I had before with it needed leveled all the time
 
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I have used that additive you mention for in between pavers, very popular over here. Didnt think of using it under the pond though - great idea.
I was being such a perfectionist when installing, it has not moved since installing it.
As my pond is fully above ground, with retaining walls all around, I was able to sit the shell in and backfill all around the sides. I filled the pond in stages keeping pace with the sand being filled around the edges. As I added sand, I kept washing it down with a running hose until the sand stopped sinking.

I have emptied the pond now, ready to re-level. the low side has to come up by 3cm or approx 1.1 inches
Walking gently around in it while cleaning, I was happy not to find any soft bits where voids might be - all nice and hard underfoot.

I am very worried about a star crack I found ! Now I remember denting this on a sharp corner when fitting the shell 11 months ago. It looks quite bad, but I dont think its leaking, as my water level doesnt seem to fall on cool days. On our regular 95f to 108f days however , I tend to lose quite alot...

crack.JPG

Do you think I should patch this ? I have 2 part epoxy cement - would this be OK ? Its a fibregalss shell with a black coating. The coating seems to be hard plastic.

Here is my Pond so far.
front view.JPGside view.JPG
 
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addy1

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Thats sounds good, Ill pick some up tomorrow from the local hardware store and patch it.
I've marked the water level to test for a leak overnight - hopefully its not leaking.
Thanks for the complement, ive finally been able to build this pond to my dream specifications.
Started the brickwork construction about 3 years ago, and then had to finish landscaping the rest off the backyard first.
You know what, ill start a build thread now, and let this one die, as my original query is sorted now
 
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Forgot to say, I re-levelled it today, and got it pretty close.
I stuffed up a bit though and forgot to keep adding water into the pond as I back washed sand with water down the sides and underneath it. The front right hand side floated up a bit ( on all the water underneath it) but I can live with the result, its only out now by quarter of an inch over approx 12 Feet.

With the pond empty, I was able to mark the new required height and raise the shell up on blocks, then use a PVC pipe connected to my garden hose to probe down the sides and ensure there are no voids under it. Once the water and sand stop disappearing and start to pool on the surface, you know that area is done and you just work your way around the pond.
 

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