Possible Aquascapeing Ideas (with high-tec 3D graphics)

[Carr]

With 4wpg you'll have to be extremely conscientious with the diy co2 in a 55g and do it on a massive scale with many bottles involved. I would definitely recommend pressurized for a tank with that lighting, from both a financial standpoint and a practical one. Any minor lapses in co2 levels, and with that lighting, algae could become a major issue very quickly. My 30g tank has only 2wpg with poor reflectors, and when my diy co2 slacks off, I have major bba issues which usually involve my doing a bleach dip on all affected plants, every time it happens. Not fun. Fish don't eat it, and once it's there, it doesn't die unless you physically kill it. I have cheap plants and it doesn't bother me if I lose a few here and there, but I can't imagine what would be the case if I had 4wpg, with a 55g tank to take care of. I'm not saying it can't be done, but just be prepared and plan accordingly. Also, once you start doing co2, you can't really stop without having big repercussions to the plants for a while, lots of die-off, lots of algae, so changing your mind part way through when you realize how much work it is to keep your diy going, will be much worse than just sticking with low light, low light plants and no co2 from the get-go.

[Proplanter]

Well, at the moment my budget is not getting me a pressurized Co2 system any time soon (well maybe, there is always the lottery).

We will see how the algae plays out, I haven't had that many problems with it in the past other then green water.I may just hold off on the Co2 for now, the majority of those plants would do fine in less light, meaning I can save on that too and just keep my 4 standard 40 watt (which puts me at about 3wpg) fluorescent daylight bulbs, rather then upgrading those.

[SerVo]

I've never had a problem with lack of co2 in high wattage light wattage tanks.  I've had tanks up to about 6wpg setup for freshwater and algae hasn't been a problem unless I got careless with ferts.
As long as water quality is all good (nitrates, phosphates, ect), algae will be discouraged.  However if your running all levels high and you drop co2... don't be surprised when algae strikes, as the plants growth will have slowed.

[Carr]

Yes, it's the fluctuating co2 that will cause the issues, not consistent low co2 necessarily. Plants adapt to higher co2 levels when exposed to them, then if co2 drops suddenly, the plants are at a sudden disadvantage as they now lack quantities needed of the enzyme needed to fix carbon from the water, which they got rid of when co2 levels were higher....algae not being at the same disadvantage, will then start taking over during the period of readaptation of the plants as they build up to higher levels of the enzyme again.

With good regular water changes, circulation, and fertilization, a non-co2 tank could be fine at higher lighting levels. Circulation is very important especially in a non-co2 tank, as co2 is constantly being depleted and needs to be replenished at the surface. You should be able to see all the leaves waving in the water, if you have good circulation. Usually this means adding a powerhead or two in lower parts of the tank where there are dead spots.

A lot also depends on the reflectors used, these can make a massive difference in the amount of actual light reaching the tank, even doubling it, so wpg values are really a bit subjective and rather course. You could attempt the higher light and see what happens, you can always cut back; better to do this than to start messing around with co2 and have your plants adapting and readapting.