thanks peter the glass is 20mm , just thought this time a window would be a good idea, it help me to see the fish for examine they are so easy to spot sores etc , but touch wood the pond hasnt had a problem yet only a little touch of new pond cindrome, when unfortuneatly i lost my favorite fish the yamasaniski in the pictures, but i have got another filter now , it has a 1000 gallon filter system now and the water is crystal , plus another good thing with the windows is where they are placed one time in the day the sun shines though one and later on it shines though the other and the fish sit at the windows a lot of the time to keep warm ,and the kids love the windows
