VaughnH,

Many thanks for your reply. sorry i didn't put enough info. the tank has a 200w heater in it as well, i just put the 25w under gravel heater in as i read that it "Could" help the plants grow. Also for the sake of £35 i would rather have it in than have to put it in at a later date and disrupt the tank. I put reflectors on each bulb a couple of days ago, which has significantly increased the ligh into the tank. I will look at the Estimative index to see how i should be fertilizing the plants. I will be getting the c02 unit at the weekend and i will report back!!!!

Many Thanks again!!!

Ross