Planted Tank Guru
Join Date: Jul 2010
Location: Huntington Beach, CA, USA
Checking for leaks is pretty much the same whatever the equipment might be. Whether it is the solenoid, needle valve or other stuff, a soap test, done correctly, will show the leak. Of course it always make sense not to get water and soap inside anything electrical, so keep it back from the entrance for wires.
Otherwise, just cover it will thick foamy bubbles like shaving cream might look. If there is an internal leak, it will have to come out somewhere. For making the soap, I put just a couple tablespoons of water in a small cup, add several squirts of liquid soap, Dish soap/ hand soap doesn't matter. Then use something like a small paint brush to really "whip" it up into a foam that will cling to things long enough for bubbles to form. Look for places where air blows the soap away for large leaks but for small leaks wait and watch for a few minutes for tiny bubbles getting larger.
Check the solenoid but while you are at it, it makes sense to do all the parts and connections. It may save a tank of gas to take the time!
I find a soap check take less time than going to get the tank refilled.