Had a good clean out of the pond i use to keep juvenile turtles , the dimensions are 2.5m x .75m x . 3m deep. Although this pool is shallow and in full sun, there is no filter, by heavily planting with oxygenator (Elodea sp.), it keeps crystal clear.It is also the home to shrimps, snails, damsel nymphs and tadpoles, which all help to maintain a healthy environment for the turtles. The surface has some shade with duckweed and the leaves of a tiny water lily.
Turtles hibernate in here every winter, so to stop it freezing up, it is covered with a double layer of thick bubble wrap. In persistant cold such as last winter, i will use a pond heater occasionally.
This pool is covered in 50mm square strong mesh to keep predators out, especially a visiting heron. The mesh is bent, so as to give some height over the two basking logs.
I set up three tubs for putting out the juveniles first, so they can 'harden off ' as they have been kept in a warm garage over the winter. Water temperatures in the tubs can reach 20 deg C during sunny days presently, but cool down rapidly at night.