Hi All Similar to slashers post I'm in need of some advice as I'm due for bulb replacement. I have a 100l tank with 4x 24w T5 fluval life fluorescent in there... I have 2x Hagen Glo ballasts, each of which powers 2x 24w tubes. Ideally this tank needs the 39w tubes. Reason for choosing the shorter tubes is due to the 39w not fitting inside the cover hood. I'm thinking of modifying the hood now to make the 39w tube fit in there. My concern is if the 24w ballast can handle the 39w tubes. Digging around on google I've read on some post that the 39w tubes will work on the 24w ballast but not as bright as it should be....maybe as bright as a 24w tube?? if this is the case then its cool with me as I may get more light coverage I hope... (I have some dark spots with the short 24w tubes) Any one wishing to comment on this ? The fluval 39w tubes are R500 each. I know the osram ones are cheaper but are those as bright and stimulating 'for plant growth? if I buy 4 fluval tubes for 2k and if it doesn't work on my 24w ballast what a chance to take... hopefully the osram are much cheaper? where do they sell osram plant growth tubes in durban? Hows the pricing? What Colour temps to use? Also I've seen LED tubes that can fit on a normal T5 ballast. If I get the 39W length LED tube will that be a wiser option as they take lesser power and may be brighter and better for plant growth....but i know they WILL be expensive . Where do I get them? Anyone to comment or advise ? Appreciated.