Best Cleaning Solution (Soaking)

Hello compatriots,
 
I was wondering what solution/cleaner i should purchase to clean out my pride and joy. Ive owned a kaos bong for two and a half years, with an incredibowl attached to it, occasionally i'll use the bowl it came with. Its been used 1-3 times on a daily basis on average since ive had it due to the fact that im not a douche and let my roommates use it whenever they want. Its glory days of looking sexy as all hell are well behind it, and the rez is basically caked on to it. It gets cleaned probably every month or two but you can never get it totally clean. Its not really that bad, and if i cant get the rez off i couldnt care less, but if it would be possible id like to get it back to as close to as new as i could.
Ive never really used anything except the 97% isopropyl, but had some purple crap (i think it was called purple power) and some stuff that said 420 on it, both of which i used once, but i didnt think it was worth the extra $20.
so, my question is, what cleaner/solution should i use to just let it soak when i go on vacation later next month? id be gone 4-5 days.

gracias and happy toking.

 

I've tended to use isopropyl with salt and it gets the lightly rezzed surfaces clean-ish, but between where the downstem goes and the ice pinch, its like permanently got a layer of rez. Its probably too late for it to get as clean as id like, but that's life...

thanks for the response tho!