Some do grow .. I have this one..
It's has grown from size of a quarter to well a bit bigger.. lol.. I got them as "Vietnamese Featherduster", but not sure if that's the correct name for it. I also have that one in multi crown (about 4 or 5 spirals)
hey wingo I have a dead one too maybe I can use the parts from urs to fix my one. let me know if tomorrow after 8pm works otherwise weekend in front of your building should be fine.
I have one something similar to the link you provided. It works and gets the job done. Its good for me since its like a pen and I can use it in my multiple tanks. just to be sure I calibrated my one with premixed const ph solution.