Wiring a float and relay to protect your ATO pump and more

[Alberta-newb]

Excellent write up! Clear instructions are appreciated.

I will be doing a retro on my ato myself soon. I am using a gravity feed reservoir as my tank is an in wall, and the sump and hardware are behind in an unseen area. My current setup uses a simple float valve (like the Eshops brand but a cheaper humidifier float) it plugs quite often and is unreliable so I picked up an optical sensor and a direct acting 12v solenoid valve. My question is if you can recommend a good relay? The sensor is only rated at 100ma (5-15vdc) but the valve is rated at 400ma. Will a larger relay like you have used work or should I look at some "mini" one with lighter load ratings. The power supply I was going to use is a 12v 500ma.

Any advice appreciated

Francis