A lot of people always ask, "What does each T5 bulb do for my tank and the corals I keep?" Well, I decided to write a very short summary to help people out and hopefully answer your questions.
Actinic bulbs
Meant to add low-end Violet light which will excite certain pigments and cause fluorescence. They have low PAR overall and I only ever recommend them if you have 6+ bulbs or don't need the PAR on a low-light system. They appear dim to the human eye.
Common bulbs: UVL Super Actinic, ATI True Actinic, Geisemann Pure Actinic.
(Others label them as 420nm once in a while but I recommend the bulbs I named above.)
Blue bulbs
Heavy in the blue light and utilized the most by the vast majority of corals we keep. These usually cover the Violet spectrum as well and are the reason that Actinics aren't as important any more. Blue is used a lot for coloration of corals. These have a ton of PAR and should be the staple in our fixtures.
Common bulbs: ATI Blue Plus, KZ Superblue, UVL 454, Geisemann Actinic Plus
(Others label these as 460nm most of the time.)
White/Daylight bulbs
There are some differing opinions of what is classified as a daylight bulb but my definition is simple: If it isn't blue or actinic, I consider it daylight. These are used to fill in the "rest" of the spectrum. Basically 500nm up to 700nm. They tend to have good PAR and loosely replicate noon day sun. They are used to brighten things up.
Common bulbs: GE 6500k, ATI Aquablue Special, ATI Coral Plus, ATI Purple Plus, KZ Coral Light, KZ New Gen, KZ Fiji Purple, Geisemann Midday, Geisemann Aquablue, Geisemann Lagoon Blue and Gesiemann AquaPink.
The pink and purple bulbs listed above could be considered "specialty" bulbs. They have a definitive pink/purple look to them. (Please don't confuse Purple and Violet as the same thing here. Purple is a mix of blue and red. Violet is its' very own color.)
They are generally used to "warm" things up but they also make certain pinks and reds look better. These should almost ALWAYS be positioned just front of center in your fixture. That way their spectrum is a little more spread out and the light strikes the viewing side of the corals. They are wasted if put in the front or rear slots.
Actinic bulbs
Meant to add low-end Violet light which will excite certain pigments and cause fluorescence. They have low PAR overall and I only ever recommend them if you have 6+ bulbs or don't need the PAR on a low-light system. They appear dim to the human eye.
Common bulbs: UVL Super Actinic, ATI True Actinic, Geisemann Pure Actinic.
(Others label them as 420nm once in a while but I recommend the bulbs I named above.)
Blue bulbs
Heavy in the blue light and utilized the most by the vast majority of corals we keep. These usually cover the Violet spectrum as well and are the reason that Actinics aren't as important any more. Blue is used a lot for coloration of corals. These have a ton of PAR and should be the staple in our fixtures.
Common bulbs: ATI Blue Plus, KZ Superblue, UVL 454, Geisemann Actinic Plus
(Others label these as 460nm most of the time.)
White/Daylight bulbs
There are some differing opinions of what is classified as a daylight bulb but my definition is simple: If it isn't blue or actinic, I consider it daylight. These are used to fill in the "rest" of the spectrum. Basically 500nm up to 700nm. They tend to have good PAR and loosely replicate noon day sun. They are used to brighten things up.
Common bulbs: GE 6500k, ATI Aquablue Special, ATI Coral Plus, ATI Purple Plus, KZ Coral Light, KZ New Gen, KZ Fiji Purple, Geisemann Midday, Geisemann Aquablue, Geisemann Lagoon Blue and Gesiemann AquaPink.
The pink and purple bulbs listed above could be considered "specialty" bulbs. They have a definitive pink/purple look to them. (Please don't confuse Purple and Violet as the same thing here. Purple is a mix of blue and red. Violet is its' very own color.)
They are generally used to "warm" things up but they also make certain pinks and reds look better. These should almost ALWAYS be positioned just front of center in your fixture. That way their spectrum is a little more spread out and the light strikes the viewing side of the corals. They are wasted if put in the front or rear slots.