The "Baptism Tub" Cryptarium

A church was selling this "Baptism Tub" on ebay- its a big industrial plastic tub that I've put on a base of milk crates with a timber frame around it to stop it bowing out from the pressure of the water inside.  I'm growing crypts on a row of inverted milk crates inside the tub.  This allows the tub to hold a large volume of water to help stabilise the temperature.  We have vary variable weather here and my glasshouse temperature fluctuates wildly and can get screaming hot in summer.  A sheet of greenhouse plastic over the top keeps the warmth and humidity in while its cool... but in summer I'll switch to shadecloth so it breathes a bit better and I have some misters on a timer to cool the air down.  In winter I'll have to put a heater in the tub as its common for the water to get below 7C.