water valves very tight

[fishguyxd]

In my piping setup I have two valves and they are "real tight" I thought they would loosen up after a while but they have not

Anyone have idea what I could use to loosen these valves up(some type of watertype grease but reefsafe. problem is I can't take them apart I would have to just reach in with brush. etc

(I would change them out for a different type but there glued in)

[mr_alberta]

Silicone Lubricant I hear works very well for things like that.