A Few Indoor Pond Questions, Please Read,

[Jamesvfr]

Hi all
Currently got an 8ft 350 uk gallon tank with a perruno cat (just over 2ft) + a redtail cat (just under 2ft) in it, both are very placid + friendly
In another tank i also have a baby redtail x tiger shovelnose cat which is growing fast

Beacause of these 3 im looking at building an indoor pond
i can build a pond 8.5ft x 6ft + im thinking 3.5ft deep so i can still look down onto them
This works out to be 5194 litres / 1142 uk gallons

What do people think of this for size considering i would also like a ray or 2 + an arrowana if it will be ok?

I would have a large above ground pond filter where i would place 2 of these heaters so they are out of harms way

http/cgi.ebay.co.uk/Weipro-MX1014-1000W-Titanuim-Heater-for-Aquarium_W0QQitemZ370312844996QQcmdZViewItemQQptZLH_DefaultDomain_0?hash=item56385d96c4


The walls would be built using 4x2 timers similar to a stud wall then re-inforced with angle steel + insulated, then lined with 18mm ply + lined with 35mm celotex insulation

My other questions are what would thickness liner would you suggest to use or would you suggest a different way of lining the pond?

I would like a good size window or maybe 2 smaller windows, how would i do this?

Once heated would you expect it to cost much to keep heated taking into account the amount of insulation im using?

I have concrete floor so there no problem there

All comments + suggestions greatly appreciated
Thanks
James

 

[OldMan47]

The water depth is going to be your enemy on this build. A simple stud wall type construction does not have a lot of resistance to sideways movement but that is what the water tries to do at the bottom. You could probably get away with building by laying stacked 4 x 6 timbers for the bottom foot and a half and then reducing to a top layer or two of 4x4 timbers. By using something like 1/2 inch rebar to join overlapping timbers at the corners, you might get enough strength in the walls that even being 8 feet long would not cause a blowout. The total force along an 8 foot section of 4x6 calculated assuming the actual thickness is only 3 1/2 inches comes to 288 pounds at a 2 foot depth and to 433 pounds on a 3 foot depth. It is holding back that force, even with 1/2 inch rebar, that becomes the problem. Don't forget that a single wall of the 2 foot depth tank feels a total force of 14860 pounds while the total on the 3 foot depth is 29720 pounds. When you join that wall to the 6 foot wall the rebar feels the force of both walls at each corner. I am assuming they are being stacked more or less like a running bond in bricks where a side extends over an end but on the next layer an end extends over the side in an alternating pattern. By joining in that pattern, each side can hold up the one next to it rather than you needing to come up with some kind of external bracing to hold back all that force from the water. Since you will be alternating the timbers, only every other timber in a wall is held at the corner directly so you would need another rebar maybe 8 inches from the first to hold the shorter timbers at each end of each wall. If you can build the strength that you need, you should have a heavy layer of timbers that are also providing a fair amount of insulating value by the thickness of the wood wall. That may save you trying to insulate it separately.
For a liner, I would use a heavy pond liner such as you might use for an outdoor pond. They are specifically designed to hold water for fish so I would expect the material to be safe to use. As far as the heat is concerned, the 2 KW of heat that you were considering using might be enough if you started by lining the space between the liner and the concrete floor with an inch or more of polystyrene insulation. Although the total force on the bottom is enormous, the pressure per square inch is less than 2 pounds on the 3 foot pond soo the strength of the polystyrene itself should suffice to hold the water away from the cold concrete.

 

[Jamesvfr]

Some good calculations there

Ive got this thread on monster fish keepers too - http/www.#99###.com/forums/showthread.php?t=296570

Im changing the plan + idea already
I basically need to do is as simply, easy + as quickly as poss when i start
Im now thinking along the lines of still doing it a bit like a stud wall with the timber uprights approx 12" apart + held together with noggins then with 1" maybe 2" box section steel corner uprights with a couple of uprights along the longest edge + then using the 1" box section to go between the steel uprights at the top edge, half way down + along the bottom, i could even brace the lower steel support between the 2 sides under the base
I would imagine then that with the steel, timber + ply it should be plenty strong enough

Also looking at smoothing + filling any screw caps + joins in the ply after build + fibreglass lining as it will make it easier for building the window + less worry about liner getting a hole etc

Ill try + do a sketch of what im thinking + post it up on here

Thank you for the reply, good to speak to someone in the know
James