Clifton C
Jack, we grew up with electric tea kettles and always used white vinegar. 50/50 solution. We also dropped in a little wad of stainless steel wire that would collect the scale. Not sure how or why it worked but it did. I looked it up, here's one...
As much as you use your steamer, it's something to consider...
Ps. We didn't clean it after every use, just every once and a while, sometimes it ended up looking like a little golf ball and we just replaced it...