Pond sealing?

hi all,
well im building a water wall feature at the end of my perogla which will have a pond at the bottom (all brick work). now i just want to know some different options for sealing my pond.
POND MEASUREMENTS: 2000mm long, 500mm wide, 600mm deep
It has 100mm concrete floor.

OPTION 1: make a mould to size and shape and get local fibreglasser
to glass it rough estimate was $500

OPTION 2: stainless steel bent to size and shape and welded
rough estimate $???

OPTION 3: render inside and use some sort of water tight/proofer paint

i dont want to spend a fortune but i want it done right and water tight for years to come, and it also has to have the inlet for the pump in threw the back wall of the pond which will have to be sealed properly which is why i havnt wrote down a plastic liner due to being to hard to seal that inlet.

open to all opinions and suggestions so post away!!!
cheers tim

Gday Tim, a couple of Bondall products come to mind, no affiliation just have a little bit of knowledge on their stuff.

They have Aquatite & Pondtite, the former is grey coloured the latter is available in a couple of colours. They are a flexible membrane type coating that you would paint in two coats over a concrete/cement type substrate.

They also have Silasec, that you would mix with GP cement to make a waterproof paint that you could paint the inside of a concrete pond.

The silasec would work out cheaper for the coating but would require a better quality substrate than the flexible types, and wouldn't have any flex if there is ground movement.


Could also use a bitumen type coating such as Gripset for a membrane type coating, would be black though.


Cheers....................Sean

About 4 years ago I built a large fish pond, kidney shaped, 5 x 3 x 1.2 metres and 7000 litres, built with concrete blocks and rendered. I don't remember the name of the produce, but is is a 2 pac epoxy used to seal rainwater tanks and cattle drinking troughs, 2 coats, not noticed any leaks in 4 years. If you go to a trade paint shop they should be able to help, cost about $80 for 5 litres and a good range of colours.

:2tsup: :2tsup: :2tsup:

Thats a swimming pool :D

as previously mentioned, Silasec, works well, follow the instructions on the bottle.

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Originally Posted by dazzler

Thats a swimming pool :D

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You know your right.:2tsup: :2tsup:

Laynlo instead of going through the wall for the inlet pump this inlet you are referring to is the water line coming from the pump to the top of the feature yes? can you go over the top of the wall instead? I built a water feature out of bushrock and had the inlet pipe go over the top of the wall that I diguised and hid with bushrocks around the edges of the pond, to take the shape out of it "to give it that more natural look" and it sits under the mortar joint between two rocks,i used inch plastic tubing that came from the pump went into a t piece and branched off to two seprerate outlets to give an even spread of water over the rocks just remember when laying the rocks at the very bottom of the feature on entry to the pond, to let them overhang as this also hides the pipe as well no holes no leaks I say

Mate any reputable pond sealer on the market does the trick just remember when applying first coat, brush all vertical strokes then second coat all horizontal strokes or it could be the other way around ?as this binds the two coats of membrane..

Couple of Coi Carp some plants around it Beaudiful

I believe that you're restricted to 300mm depth before a safety fence is required as well. Ausdesign would know the regulations.
I know that it's unlikelly, but if some kid does happen to drown in it then you'd probably find yourself in big trouble if you've broken any rules.

What is most suitable for an existing pond that has cracked and the water is seeping through the crack in the concrete. We have a lot of fish in the pond so this is going to be a problem. It will be necessary to drain the pond for sure but will the products mentioned in this thread be suitable for this. We did drain the pond about 4 years ago and cleaned the concrete and painted it with a pool paint which looked okay but now the crack has appeared and will need fixing in the near future. Not losing much water at the moment but guessing it will get worse as time goes on.
Obviously the pond sides and bottom are covered in a thick slime and that will have to be removed and the whole thing cleaned again.

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Originally Posted by scooter

Could also use a bitumen type coating such as Gripset for a membrane type coating, would be black though.

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Would this be okay to use where fish will be in the pond.
The pond is quite large, haven't measured it but about 6 meters X 4 meters I would gess so I need something pretty cheap.

Laynlo,
I've built a few water features over the years and stongly believe most piant on membranes are unreliable. $500 is well spent on a FG liner, get them to install it, so if it leaks its their problem.

Ive built $100K+ features out of reinforced 300mm 32mpa concrete shells with Xypex and 2 pac paint that still leak.:rolleyes:

The trick is knowing where the leak is so you can fix it. If you use the FG the only place it could leak from is the inlet pipe and a tube of silicon can fix that.

As far as safety goes I would fix a stainless mesh covering just under standing water level. It would need to be removable for maintenance but stong enough to hold someones weight... not that easy...

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Originally Posted by munruben

What is most suitable for an existing pond that has cracked and the water is seeping through the crack in the concrete. again.

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Munruben, there are products available that you can apply to the outside crack,even when wet that can seal it.

Having said that...I can't remember the name of the stuff....I think we called it "fire clay". It comes as a dry powder that you mix with water to a render consistancy and trowel it on.

There is also a method of injecting the crack with something that will seal it...but I have never done that one. Ring Dirk from Waterforms International 02 9558 1579 he's the man!:)

I've heard of something called 'bentonite' clay. Waterproof, non-toxic, expands when wet. I believe that it's used on dams, irrigation chanels etc.

Hi Prawnhead, good to see you back.
Yeh Bentonite blanket is a layer of bentonite clay sandwiched between two layers of fabric. You use it as a dam liner if you can't find any non dispersive soil nearby. I don't think it would work to repair a leak.

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Originally Posted by Bleedin Thumb

Munruben, there are products available that you can apply to the outside crack,even when wet that can seal it.

Having said that...I can't remember the name of the stuff....I think we called it "fire clay". It comes as a dry powder that you mix with water to a render consistancy and trowel it on.

There is also a method of injecting the crack with something that will seal it...but I have never done that one. Ring Dirk from Waterforms International 02 9558 1579 he's the man!:)

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I appreciate the information and have noted it down. Thanks a lot, much obliged.
I knew somone would come to my rescue. Great forum eh? :2tsup:

As mentioned a liner would be the best bet longevity wise. I have done ponds and waterfalls with previous employers where we have successfully tanked a concrete or concrete block pond, but if there is any ground movement, and it breaks the seal of the membrane (even though they are part flexible) there goes your water.

If you line it with some real heavy duty butyl rubber or the like and conceal it properly it will be fine for years. Just beware of things that can cut the material, in some instances you can use an underlay or sand underneath.