Water sensor for fish tanks

thingiverse

Here's a DIY water sensor I built for a buddy of mine that can be easily hung in a fish tank corner to alert when the water level reaches a certain point.\r\nIt is programmed to trigger an alarm 6cm or 3cm below the edge, giving you ample time to take action.\r\n\r\nTo get started, you'll need a small switch, preferably one from an old printer, a 9V clip, some perfboard, a piezo speaker and a ping pong ball.