Experienced Pond Builders Advice

Hi all, 
 
I am looking for some advice from anyone who is experienced with pond building/making. 
 
I am looking to start a project and build a wooden raised pond for my two goldies who are getting a bit big for their current pond which is a plastic preformed pond only around 80 litres in the middle of the garden. 
 
I have some materials, Timber boards which have a thickness of 2 inches, polystyrene sheets which is 1 inch thick. 
 
I plan on building the case from the timber planks,which will be treated for outdoor use lining with the polystyrene for insulation then either concreting over or using a pond liner pvc sheet. 
 
What i would like to know is -
 

• is the timber suitable for a wooden pond
• will the polystyrene be of any use at all
• and what is the best form of covering the inside, concreting or pond liner (I already know everyone is going to say the pond liner but I just want to get an opinion on the concrete)

 
I have enough timber to build the pond around 4 ft length, 2 ft height, and 2 ft wide making it about 150 litres if my calculations are correct. 
 
This pond is only for my two goldfish, 1 common and 1 comet which I have had for around 2 years and are now getting to a nice size, they were first in the fish tank for about 18 months and have been in the pond for about 6 months. 
 
Obviously I will put an overflow and a tap for draining in, just want to know about the basics really as I have never built a pond before, but really want to. Thanks in advance.
 
If the image works this is how I want it to look, just different size obviously.
 

I built a small raised pond a few years ago.
I used 2" thick tannalised timber for the outside, I lined it with old blankets for insulation & used a pond liner, my fish have survived the harsh winter we had a couple of years ago with temps down to-18.
I can see a problem with using concrete to line it, the wood will expand & contract in the different temperature & could cause the concrete to crack

We have a 8ft by 4ft by 4ft concrete pond my grandad done about 23yrs ago no problems, however this has brick around it not wood.

Plastic/rubber liners do need replacing every 5-15 years depending on quality. Concreat will probably last longer than you if done well, again donno how this works with the wood.

I did this a few years back. Just make sure you got a solid backing to render to. Plenty of waterproofing agent. Fibres added to mix can stop it cracking. And pond paint on finished product

Welcome to the forum, kevcann.

That's a lovely looking pond; got any pics of it all filled and finished? I'd love to see

fluttermoth said:

Welcome to the forum, kevcann.That's a lovely looking pond; got any pics of it all filled and finished? I'd love to see

Click to expand...

Sorry only got pics when I did it.

If you decide to use cement render you need to use breeze block to render to. So have to build it all. Can use wood around it if raised for decor. If you want a shape to it as the pic I put on. Drill and plug metal lath sheets to the inside of the block overlapping and make sure there tight. plenty of screws and use steel washers so screws don't pull through. Put two coats of render on. First one pushed through the metal lath so there's no air gaps behind and make sure it's all completely covered. Once covered it needs slightly scratching so next coat can be applied. Leave it over night before second coat. Once that's done you can use a car sponge to smooth it over.these pics show the scratch coat,start of the second coat and finish product.