There are those who in emergencies,, Myself incuded, have utilized different sized plastic bottles filled with water and frozen. These can then be placed in the aquarium to cool the water. Larger two litre jugs for larger aquariums,and smaller bottles or jugs ,for smaller tanks.
For do it yourself chillers in my view,, It will be the length of the coiled tubing inside the DIY chiller that determines it's effectiveness by providing more contact time inside the DIY chiller. Many of these small fridges used for some DIY chillers, are much better at insulating already cold products than they are at actually cooling something such as warm water given that the water will be constantly moving in and out . Thus the length of the coiled tubing , plastic,, (wouldn't feel comfortable with copper) ,should have considerable length to allow for longer contact time as mentioned. Just my Two cents. |