Downranked Holy LightFollow

So, I've got my stats up to the point where I feel I can start healing heroics and Raids (1300 +heal, 17% crit, 90mp5), and I've noticed that unlike in regular instances, I have to use holy light more often. This is particularly true in heroics where I'm the only healer and I may need to heal an overzealous DPS'er, or there's an AOE attack. By the time I get back to the tank he's often taken considerable damage. So, it's really nice to have that extra half second from Light's Grace. My question is, do you guys weave a lower rank holy light into your normal rotation in order to ensure that Light's Grace is always up? And, if you do, what rank do you use in order to maintain mana and time efficiency?

Well when I was healing SSC/TK I was mostly using flash of light to heal. When I got to black temple, spike damage was such that I had to start using Holy Light all the time. When that happened I switched to the libram that gave me extra mp5 (I need all I can get now) and weave rank 8 when nothing big is going on and rank 11 when I need to. However this uses a ton of mana, and I eat through mana pots like nobody's business. One night a couple weeks ago I literally went through 22 mana pots in a single might. That's why I usually bring at least 40 whenever I heal something. But anyway, yeah I do weave them in my casts, especially with this libram.