Hi Anna, the packets you are describing sound different to what I had in mind. I thought you meant potato chips from the deli etc. I tried a simular reflective material and it was ok for about 3 months but then become very brittle and as soon as you tried to touch it, it just broke up into tiny pieces. Actually when I think about it, its probably the light that makes it brittle rather than the heat. Hydroponics shops stock mylar and you can buy it by the metre, it should only cost a few pounds for that amount. Sorry cant suggest any stores as I dont know where they are in England but in Australia we have hydroponic shops everywhere. Actually hydroponics and aquariums are very simular and share a lot of the items needed: water pumps, heaters, ph testers, air pumps and stones, lights etc etc. I,ve noticed sometimes the same item in the hydroponic shop is quite a few dollars cheaper than in the aquarium shops, its worth checking out if you have a store nearby.
