First grow

A week today since the popped seeds went into coco. 7 days and it seems to have grown fairly quickly. What do you think guys? I'm under a 315w maxibright cdm with a Phillips daylight bulb on 18 hours. I'm watering every other day on average (when the soil feels like its beginning to dry) and using nutrients in every other water. The lights are very efficient and don't give off much heat so I'm struggling a little temperatures. Room temp is around 18C which is where the intake is drawing from and the temt only gets up to about 24C bir drops to 18C at night. It's a small 1.2x1.2x2m tent with four 12l fabric Rhizo pots so there's no room for a radiator. I'm really not for the idea of using a heat fan and leaving it while I'm out so I've purchased a 90w tubular heater. I've read they're not brilliant but if its tops the temp up by 2/3C then it will he perfect. Has anyone else used one? Do the plants look good for 7 days old?