WOW, thanks Ghengis for that great info, and Joan for asking. I bought a Fluval Edge aquarium and it has 2 x halogen lights just above the filter water-fall & they make the top water super hot. Because of their spotlight effect, they also leave very dark corners in the tank.
So, I rang around various local LED specialist shops and got prices of around $50 per globe, yikes!!!! I had no idea they are actually manufactured from crystals that are grown in labs, the outer part of the crystal being the lowest grade.
Anyway, I got some cheapy LED's on ebay ($30 for x 2 but they didn't have the little plastic lenses/covers over the crystals) and the darn things failed within a couple of days, from the moisture I dare say. Lesson learnt yet again about spending good money after bad!
However, when I have the money to buy some decent LED ones, it's great to know I can turf my plastic plants & get some real ones happening - didn't think you could under LED!