You're growing in an AG so the last thing you want is more stem. Keeping your plants as low as possible will allow you to flower in your AG.
You urgently want to cover the holes in your AG where you don't have pods. Light in your reservoir will encourage growth of bacteria and other nasties.
As many have said, you would be wise to invest in an air pump. Just go to Big W, buy there 2 outlet aquarium airpump for around $15, and get 2 of their long bubblers, not the air stones, but the more expensive perforated rubber tubing so there wont be any powdery buildup in your AG pump from disintegrating airstone. All up won't be more than $25 and it will not only greatly decrease your chance of root rot, but will also provide more oxygen to your plants.
Next time you're in the big smoke, go to Ikea and get some of those lamps in the picture I posted. They can handle hig wattage globes, they are sturdy, and they are cheap. As I've said, it's hard to find lamps that will fit powerful CFLs, unless you know a spary who can whip you up a quick light fitting.
Hmm you look like you have a little yellowing in the tips of your leaves too. Have you checked your pH? Big W also sells aquarium pH testers and pH up and down. The testers are easy to use and will give you an accurate enough indication of your pH. pH up and down are just bi carb soda and an acidic powder, they're not dangerous and are easy to use. You fill up a clean bucket with your tap water, put one of your airstones from your AG into the bucket and leave it for 24hrs to allow the chlorine to evaporate. Then test your pH, and if it is much above 6.5 or below 5 then you'll want to add pH up or down accordingly to get it close to 5.5-6. Add 1/4-1/2 teaspoon of pH up or down to your water and give it a good stir with the airstone going too, then check your pH. Keep adjusting slowly until you get it where you want it. Once your pH is good, you're right to add the water to your AG reservoir knowing that your plants are getting clean oxygenated pHd water to facilitate the uptake of nutrients.
Nice!