Yea I would say your hairgrass is going to slowly die. Water plants are pretty hardy and im not suprised to see them live a couple months with lower light than they need but over time it will show. They will have slow growth if any, and will turn brown and die off. Thats the problem I face in my 30 gallon. I need more wattage. I currently only have a 20 watt bulb. I plan on making a DIY second bulb fitting though sometime in the near future. I recently bought a 2.77 gallon tank and put a red ludwigia and some kind of whispy tall plant in there i forget the name, and I use my halogen desk lamp for that tank. It is 20 watt's, so they have like 7.22 watts per gallon rofl, maybe a bit much. They should grow nicely though. For small tanks I find that desk lamps are sooo much cheaper. I don't know if it's a trade secret a scam or what but you can buy desk lamps for half the price or less than a normal aquarium light. Whats the deal with that? You might as well buy desk lamps and take them apart and make your own fixtures outa them. You get the bulb, the wiring, the switch, and the housing for around $8-30 per lamp depending on size and wattage. I could easily jerry rig those up for maximum tank coverage at a fraction of the price. Think that's what I'll do from now on.

hmmm, i might have that high intensity point source bulb... i dunno how can you tell for sure? It also is about 8 inches above the top of the tank if that helps any i dont know?

lol no more hairgrass then... guese I will try to get around 90 WPG. And more plants, mainly background plants.

how much was that and where did you get it from?

I bought the four foot long 4 bulb fixture from OSH hardware store for like $20 or something, maybe less. I also have a 2 foot long double fixture with the regular 40 watt flourescent bulbs for my 10 gallon tank.