watts per gallon is about the most innacurate form of measuring light requirements, its a outdated method of mesureing lighting requirments as a general rule you need to figure watts per distance because light penetrating say a 20g xhigh (looks like two ten gallons on top of eachother) wont be anywhere near the same as light penetration in a 20Gallon long 12 inches of depth versus 24 inches of depth, the light at the bottom of each respective tank is at completley different levels due to distance and amount of water it has to penetrate, water is very effective at filtering light down below usuable amounts for photosynthesis.
as to your question about longer photo periods, yes extended photoperiods can help make up for a lack in lighting. with your tank being a 55g you want to think not like you have 260watts of light because each side is only getting 130W of light. because the watttage from the left side of the tank does not light the right side.
If you want some thing for your clowns to host in try a toadstool leather my tomatoes host in mine and I dont have to worry about the anemone moving around stinging my corals.
corals I would reccomend for your tank.
torch, hammer, frogspawn, candycane (LPS)
zoanthids, mushrooms, ricordea yuma, toadstool leathers, chili, sunpolyps, gorgonian, Palythoas, hidden cup, sinularia dura, tree corals (placed high), (softies)
thats an amazing variety when you actually look and see all the many types of each listed. I would reccomend steering clear of anemones untill you have better lighting. I believe you would only enjoy short term success with an anemone.
I hope this information helps you out good luck with your tank.
