I am with Andy. Although I have had great success with the Kent float valve, I would be careful hooking it up directing to a sump, especially for f/w makeup. Should it stick, you will have a flood, and lots of dead animals. What I do is run the float into a 50g water container, this container then is connected to a 20 rubbermaid container via a ball valve. Once a week I open the valve and fill the 20g conatiner. The 20g is connected to the sump via a rio 600 ( I need to replace this) and an Ultralife reef float switch. Even if it stick, 20 gallons of water is not going to mess up my 450 gallons system. Build reliablity into your system and always presume that everything will fail someday. Aquarium keeping is Murphy's Law at its best.