hi guys, a quick couple of questions. has anyone tried the little pressurized co2 bottles you can buy in tescos? they are small, i think about 500g but are very cheap at about Â£3, and i think you can get them to refil them for free or for very little if you bring the old bottles back. They are normally located near the alcohol isles. Obviously they are used for fizzy drinks etc. I take it the co2 will be safe to use? i will have a check of the thread size but i guess it fairly standard (12mm i think??) Secondly, my arcadia luminaire get very very hot. Im not sure if this is meant to be right? It is a 120cm 4x54w T5. I might invest in a cooling fan (black ones that clip on the side of your tank), but are they any good? has anyone got one? i can see the advantages in the summers as my tanks get fairly warm, for a few dyas this year i totally switched the heater off and it was fine, even at night.