Point I've learned from using the temperature controllers is that I need to go a step beyond what they have in mind if I want the best use out of the probes.
They tend to be more water resistant than WATERPROOF! They last pretty good as designed but last much better if they are not in water full time and the solution can be very simple. Get a sleeve of some sort, like a soda straw for short tanks or tubing of any sort of thin material for far deeper tanks. choose a material that is fully water tight, thin to allow for faster temperature change to get through the material and for ease of working to hide it. Thread the probe into the sleeve and seal the bottom end to keep water out.
Sealing depends on your material but the easy one for me often comes down to lighting the end of the straw on fire and crimping it out. Pliers often works good for this but stepping on it on a concrete floor does it, too! If using a straw and water may get into the top, I also cover that with silicone as I assume there will be times I screw thing up and drop it in the tank!
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