My helium balloons don't rise
Inflating a Double Bubble Balloon w/ Helium [Image source: i.ytimg.com]
I put a coloured latex balloon into a Crystal clear balloon. I then added one full pump of hi- float, filled the balloons with helium and knotted. The 3 balloons that I tried, hovered just above the ground. Why?
From your description, it's not clear to me if you used the Hi-Float only in the inner balloon or also in the outer balloon? Also, what sizes were the two balloons?
I would suggest that you treat both balloons with helium before you slip the colored balloon into the crystal clear one.
Possible reasons why your double bubble doesn't float properly...
* Too much hi-float got injected into the balloons
* Balloons not fully inflated (try pre-inflating the balloons with air before you treat them with hi-float)
* Helium cylinder contains a helium/air mixture with too much air
Hi-Float has a great Troubleshooting Guide
and instructions that may help you solve the problem.