Planted Tank Guru
Join Date: Jun 2004
Location: Baton Rouge, LA
There was a thread years ago where someone was wondering if he could DIY something unobtrusive that could be placed under an entire tank setup, and detect any leak, no matter how small. Just off the cuff, I suggested two layers of aluminum window screen, separated by a layer of fabric which had been soaked in an electrolyte solution and allowed to fully dry. Should a leak occur, it would wet the fabric and dissolve the electrolyte, which would make the water sufficiently conductive to allow current to flow between the two layers of screen. A simple circuit would be able to detect this small current, and switch on a higher current device, like an audible alarm. Bonus points if it could also call a cell phone. I don't think he actually tried it, though.
If you have something that is likely to capture and contain at least part of a tank's water capacity (epoxy coated basin, buckets, etc.), then a float switch - as used in air conditioning drip pans - would be a much simpler way to trigger an alarm.
Of course, neither of these stop the leak, just help alert you to it before too much damage is done.