Weed stuck in my Halo

I picked up a Halo single perc bong a few weeks ago and I love it. I couldn't get weed for a little tho and didn't clean it in the meantime which was a mistake. In the halo part right above one of the holes there is what looks like a ring of calcium buildup (our water-softener broke and it hasn't been replaced) and in the calcium there is a tiny piece of weed or thick residue which is really annoying to look at. I'm pretty dilligent about cleaning my bongs but when I couldn't get weed I said f it and put it away. I've tried everything you can think of since, here is the list.
Formula 420, 91% rubbing alcohol plus salt, coca-cola, CLR, boiling water, and as of yesterday acetone. All of those were left to soak seperatley of course for at least a day and had minimal effect. I've been smoking from my old Roor and I really want to use my Halo but I need to get it clean especially after letting it soak in the chemicals. Does anyone have some suggestions on something stronger that will remove the residue. I'll get a picture if I can but I don't have my own camera and I've had trouble downloading pictures from my friend's in the past.


Thanks

If its calcium, and CLR didn't take it out, that is some serious build up.

If its all glass, you can try muriatic acid. It's sold in the paint section of the hardware store. Its also used for swimming pools.

Put that in it and let it work its magic, then rinse the hell out of it with water. My dad used to do small appliance repairs and people would bring in their MR. Coffee units that would get plugged up with calcium and lime. He would use the muriatic acid to flush them out (The water tank was metal in them days) and would have to pull the heater and tank out and bust it loose with a ball peen hammer for the real stubborn ones.

NOTE: Muriatic acid is not good for your skin, and has a pretty powerful fume to it. Have good ventilation and wear gloves and eye protection when handling. It may sound like over kill, but you do not want that stuff to splash in your eyes.

HAHAHAHAHAHA you tried CLR.

Sorry I'm baked and that was just hilarious to me.

i use a bottle brush for all those hard to reach areas, sold in most supermarkets and pharmacys, same ones you would use to clean a baby bottle, that combined with rubbing alcohol and salt has allways worked for me