Compact fluorescent bulbs

Does anyone know much about the energy saver bulbs made for household light fittings. Here is an example:


I understand they don't disperse light as well as T5s, but do they offer the same (or similar) spectrum? Phillips offer "cool daylight" flavour which seem brighter and bluer than the 6,500K T8 bulbs I have which are similar wattage (22W T8 vs 24W Phillips spiral).

How suitable do you think they would be for a reef tank?

 

IMO- not suitable for lighting the reef tank -but perfectly good for lighting a refugium housing macro algaes under the main tank

reasons
wattage is a unit of electricity consumes, and does not in any way indicate the amount of light output or the efficiency of the light

with a T5 tube you can fit it inside a decent reflector and get majority of light going where you want it

with a 2 U or 3 U or a twist or spiral energy saver, much of the light produced heads in the direction of the glass next to it, rather than in the direction of your tank

its very hard to find a decent reflector that will compensate for that

additional, Kelvin spectrum of 6000 - 8500 often sold as cool white or daylight white
is towards the yellow end of the spectrum making it much better for algaes and water plants than it is for corals

you want lamps of 10000 or higher over a reef tank - with many people using T5s of 14k (aquablue range) and higher to get the best results in terms of coral colouration

Steve