pond windows

[JonoB_uk]

I am at the planning stage of building a formal koi pond. Nothing too big so currently plan it to be 12'x8'x4''. It will be raised about 18" - 2' out of the ground. Above ground will be block work walls but underground it will just be earth. I will line it with a rubber/butyl liner.

I have been looking at lots of pond pictures and I really like the idea of a window. Does anyone know if this is possible with a lined pond? My first thought is to make a wood frame. I would overlap the end of the glass by 2" or 3". I could screw uPVC cladding through the liner onto the wood with the cladding also covering the 2" or 3" that goes over the glass. With plenty of silicone sealant being squeezed by this sandwich it seems to my uneducated brain that it should seal.

Excuse the picture. As you can tell I am no artist but it might help explain. This is a view from above.

Any thoughts?

If the window was 24"x15" any idea how thick the glass would need to be?

As the window would only be partly submerged would I need to take precautions to stop the pond freezing?

 

[koikeepr]

yes, I have seen exactly what you're talking about. You could stand on the side of the pond and see the fish swimming by. Very cool.I think your biggest concern has to be to get a piece of glass that is strong/thick enough to withstand the force of water against it so that it does not break.

The pond I saw that had a number of long, horizontal rectangular windows and built of brick walls on the above-ground part and it had to have been at least an inch or 1 1/2" thick. It was not wood. Basically, it was like the type of glass used in one of them huge city aquariums.

I don't think it would freeze once you used the right thickness. Before you start this, I would visit your local glass guy and discuss with him what you are looking to do and how the glass would need to be placed so that it would stay secure and not fly out with the pressure of the water. You might want this step of the process to be handled by a pro.

 

[JonoB_uk]

You are probably right in that I need to find out if I can get a piece of glass suitable before worrying about trying to seal it to the liner.

Another view of the idea. I would prefer if I can keep the top unframed like in the picture. Assume the blocks have been rendered white as I don't know how to make Google Sketchup do block work!

Does anyone know how to calculate the pressure that will be on the glass so I can find out the cost of toughened glass in the size I would like? I would be very surprised if it needs to be more than 1/2" thick. As far as I know the pressure is linked to depth not the size of the pond otherwise ships would be crushed when going to sea. If that is true then it would be much different to a 15" deep fish tank. That can't be true though as a 1"x15" picture frame type fish tank would the same pressure as the end of a 15"x10' fish tank and I am sure that isn't right. Pond design is hard!:100:

I can easily push a liner away from the supporting wall at a depth of 15" so I don't think the pressure will be excessive. If I keep the length of the window fairly modest then I would have thought it was possible.

 

[koiguy1969]

acrylic may be the material to use...just a thought!

 

[aviator79]

Think of a home aquarium. The glass is not that thick and I think only the bottom is tempered. The increase in size of the pond is not going to make an increase in pressure. The tickness of the class has to do only with the surface area of the glass and the depth (where the pressure would be highest) as far as I can think recalling what I know of physics. Im sure also if it is not square than there are other variables like if it was super wide there would be exponentially more bending stress on it. Now if you’re dealing with freezing water against the top that may be an issues. Anyways I found this:
http://saltaquarium.about.com/od/diytanksrefugiums/ss/diycustomtank.htm
Which on the second page links to this:
http://saltaquarium.about.com/gi/dy...u=http://www.fnzas.org.nz/index.php?PG=glass1
Which at the bottom has an excel sheet for calculating thickness. I attached. Change .txt to .xls

 

[JonoB_uk]

Think of a home aquarium. The glass is not that thick and I think only the bottom is tempered. The increase in size of the pond is not going to make an increase in pressure. The tickness of the class has to do only with the surface area of the glass and the depth (where the pressure would be highest) as far as I can think recalling what I know of physics. Im sure also if it is not square than there are other variables like if it was super wide there would be exponentially more bending stress on it. Now if you’re dealing with freezing water against the top that may be an issues. Anyways I found this:
http://saltaquarium.about.com/od/diytanksrefugiums/ss/diycustomtank.htm
Which on the second page links to this:
http://saltaquarium.about.com/gi/dy...u=http://www.fnzas.org.nz/index.php?PG=glass1
Which at the bottom has an excel sheet for calculating thickness. I attached. Change .txt to .xls

Thanks Aviator79. I am in the middle of reinstalling this pc so I can't open .xls files yet so that bit will need to wait. It does look like the actual glass thickness isn't too much of a problem. I might go see how much it is and overdo it as I suspect being knocked is more of an issue. My fish tank has reinforcing pieces to give it strength and I want to try and keep this pond window clear of bracing if possible.

I suspect acrylic would be too easy to scratch in a pond environment. I am expecting it will get green algae on it quite a lot given it is exposed to plenty of light so cleaning it will be an issue if I went the acrylic route.

I am getting excited by the idea though and the window may be about to become 30" long :banana:

 

[koikeepr]

I think it will look beautiful. Based on your pond measurements, it seems like your gallonage would be 2880 gals. I would use 3000 gals as a safety point. Go to a glass/window installer and tell him what you're doing and tell them you need a glass thickness (tempered) that will be able withstand water pressure from 3000 gals per square inch. They will make a suitable recommendation for you for how thick your glass should be. I would suggest glass instead of acrylic for the same reason you describe--scratching.

Also, tho glass appears "clear" to us; much of it has a greenish tint. You can get glass that is more "clear," but I know it's more expensive. But, I would suggest you spend the bucks and go truly clear if you want to really appreciate the color of your koi and not have the glass show a greenish tint to muddy the colors of your fish. Again, the glass guy will be able to help you solve this problem.

I look forward to seeing pics when it's done. Sounds like a nice contemporary look.

 

[JohnR]

As aviator 79 stated it has more to do with depth than volume. Also keep in mind those figures in the link are for rimless tanks, When you use the glass as a window which is braced all the way around it will be even stronger.

You are making a good choice by not using acrylic. Acrylic scratches way to easy and will make viewing crappy over time. Also dont waste your money on low lead starfire glass untill you get over 1/2" thick. Sitting side by side and filled up with water you will not be able to tell a worthwhile difference with starfire untill the glass starts getting over 1/2" thick.

Do some research on plywood fishtanks and you will get great ideas about mounting the glass

 

[aviator79]

Sounds like an awsome idea. I just told my GF I was going to put a window in my pond. She had a fit! Not really loving me spending evey night outside working on it I guess. Keep us posted.

 

[Airic]

That would be pretty cool. Have your own little Sea World.

As another idea, I've seen aquariums used upside down in the water and lifted up out of the water with the open side under the water a few inches creating a suction. I saw one as a display and they would put floating food in it and you could see all of your fish really clearly.

 

[JonoB_uk]

I think this idea has passed into the design. Sadly don't hold your breath as it is at the end of my garden makeover. Will take up some of my patio area (one of the other projects) so I needed to plan it now but I am not sure the pond will get started until next spring. I have made a "55 gallon" type filter today as detailed in a different thread to test on my mother's koi pond that I dug, then enlarged and then re-enlarged about 20 years ago that has never really had very clear water. I should have perfected the filtration at least by the time I start the dig of mine. I would like to have gone another foot down but I have to dig it my hand and barrow it through my garage and then get the soil taken away so I have tried to be sensible.

That would be pretty cool. Have your own little Sea World.

As another idea, I've seen aquariums used upside down in the water and lifted up out of the water with the open side under the water a few inches creating a suction. I saw one as a display and they would put floating food in it and you could see all of your fish really clearly.

Wow, I bet that would get seriously heavy by the time it was big enough for a reasonable sized koi to visit :icon_mrgreen:

 

[DrCase]

Let us know what your mom thinks about her new filter.....

 

[koikeepr]

The beauty of going through a build once is that you recognize what needs to be improved. So, you practiced on your mom and you will do even better on yours!

As they say, pond construction is never done...we're obsessed!

 

[Otter]

I think this idea has passed into the design. Sadly don't hold your breath as it is at the end of my garden makeover. Will take up some of my patio area (one of the other projects) so I needed to plan it now but I am not sure the pond will get started until next spring.

It's not a bad idea to take some more time to think it over anyway. Problems are much easier to correct in the design phase.

I like the window idea, but what about
1) Ice
2) Falling branches, hail, confused birds, etc.
3) Temperature cycling.
4) Algae.
The first two aren't encountered at all with aquariums, and the last two are likely to be much worse outdoors. If you can make it work, though, it would be very cool to watch your fish through the window.

 

[JonoB_uk]

It's not a bad idea to take some more time to think it over anyway. Problems are much easier to correct in the design phase.

I like the window idea, but what about
1) Ice
2) Falling branches, hail, confused birds, etc.
3) Temperature cycling.
4) Algae.
The first two aren't encountered at all with aquariums, and the last two are likely to be much worse outdoors. If you can make it work, though, it would be very cool to watch your fish through the window.

I live in the UK and on the east side which has very mild winters. This year was the first time I have seen snow last for a few days for many years.

1. Ice is my biggest worry though. I am thinking I could make an insulated 3 sides of a box. From above it would look like this ] I could place it on the inside of the window inside the pond to trap and area say 6"x30" down to a depth of maybe 24". If I install a low wattage heater in this gap it should be easy to keep the ice from the window with the box taking any of the strain. This would also ensure there is at least one part not frozen over and protect my window. Excluding the effects of global warming, hard winters are very rare and the number of days when the pond is likely to ice over is tiny. The other advantage I have is that because it is a formal pond I have the option of covering it in winter. I am considering adding a pergola as heron/cormorant/sea gull protection which would make it easy to cover in the winter. A winter cover has always been part of the design so I am quietly confident ice concerns can be addressed.

2. It will be a long way from any potential branch strikes and we don't get hurricanes or anything similar. Again, due to our climate, hail in the uk is pea sized at best. (We also don't get hot weather and drizzily rain is always only a short period away. A very boring climate but we can get it all happen in the same day.) The window is tiny and I only get clever birds visit my garden :icon_mrgreen: Birds are likely to hit against the loaded side which should help. Opposite the window about 10'-12' away is my garage so they would need to perform an heroic swooping dive to hit it with any force.

3. This is a concern. I plan to mount it with silicone. If the bead is a few millimetres thick this should give it some flexibility. I am hoping this will be enough. The window is only likely to be 30" (new size :banana so I hope that the size won't change much as the temperature changes. As this is a lined pond the liner will be glued to the window and that has a lot of stretch in it so the seal shouldn't be overly stressed. Anyone have any thoughts if this sounds reasonable?

4. The window will only go to a depth of about 15" so it should be easy to reach to clean.

This tread has drifted a bit off topic into other design issues so I hope that isn't a problem. I am grateful to discuss the design as at the moment it is all just my thoughts based on lessons learnt from one pond (or 3 depending on how you view it). Don't get me started about my idea for a raised, formal stream, running along the back edge as a floating plant filter :eek2: