How to use a helium tank
For floating latex balloon bouquets or foil shape balloons attached to ribbon or string, you can usually hire a helium tank in your local area if you are doing quite a few balloons. You may be able to buy a small disposable tank locally or online at eBay or Amazon. You can also check out a local hardware store who may have tanks for hire. Also checkout these links for tank hire. Supergas, Boc, Elgas
Keep balloons away from direct sunlight and warm places. Helium expands in warm temperatures so balloons can burst if left in front of windows, in conservatories, cars etc. Avoid very low temperatures too as they can affect the float time of the balloon, balloons prefer to be in comfortable room temperatures.
Keep the balloons away from open windows, doors and breezy spots as they can be blown against sharp objects and will burst.
Make sure balloons are not near any sharp objects as they will burst! Check there are no nails in walls or sharp corners/edges close to where you are displaying the balloon/balloons as it will puncture if they brush against them.
Latex balloons are biodegradable so its normal that they oxidize (become cloudy) as they start to degrade. Heat, sun and humidity can accelerate this process.
Helium balloons can pop if they are exposed to heat & sun.
Mylar foil balloons can shrink if left in the cold or near air-conditioning. The good news is that they will puff back up once in a warm room