If you have chlorine or chloramine treated water, K.O.I. has always recommended the use of a water shut off timer whenever doing a pond refill.  In fact, they are so cheap (and they do sometimes fail, that Spike now recommends using 2 of them, one after the other.

But there is another way that doesn't involve the use of ANY device.  Read what the Fish Vet in Australia recommends.

Every so often, we receive calls from owners with fish dying from chlorine toxicosis because they had inadvertently left the hose on for too long while refilling their fish pond.

Chlorine and chloramine has been added to our tap water supplies as a disinfectant, making it safe for us to drink straight from the tap. But these chemicals are toxic to fish. Normally, we use anti-chlorine that is in proprietary water conditioners from your local fish shops. But when you forget, and leave your hose on full for too long, toxic levels of chlorine can build up in your pond.

So I’d like to share with you, a very simple, way of avoiding disasters, and at no cost, and no fancy gadgets!

Next time you need to refill your pond, why not turn the tap to a trickle, instead of a full blast?

Everyone feeds their fish once to thrice daily, so in this time, you’d be able to turn off the tap, before it overflows, and long before the entire pond volume is displaced by toxic levels of chlorinated water.

Please share this with all fish keepers, so we won’t get another case of fish kills in ponds again.

Source:  https://thefishvet.com/2019/02/05/whats-the-safest-way-to-top-up-your-fi...