Ok here we go. At my work (A petstore) we have a huge aquarium section. On those aquariums, we have a timer (digital like this, just way bigger) The timer is set to start waterchange 2 times each day on 3 different groups, and we have a option on the timer so we can make manual waterchange - And here is the problem. When we start manual waterchange, and forget we put it on, ya well.. the water will run untill we turn it of.. 02.00 this night, I got a call that our power was shut of, and I get to the store found that the water has been running from 17:30 till 02:15 when I got there. (my boss forgot to turn it off) and vupti, all fish in one section was dead.. I've earlier worked with the 555 timer and a relay, and found it very easy. What I want to do, is when the timer get a signal, it should turn on the relay (pump) and run for eg. 20min and then turn of. (I can only provide 220v here, so some sort of converting to 9-12v should be made) The timer should first be "restarted" when the signalpower is turned of. Hope you understand my problem - and if you have other solutions, please let me know! Thanks!