George Farmer
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Recently there appears to be much talk on colour temps. of tubes so I'll just try to give my view. Hope it helps.
IMO too much emphasis is placed on colour temp. (K). Unfortunately one cannot know from this figure alone how effective the light produced will be for plant's photosynthetic requirements. It is widely regarded that between 5500K and 6700K is the "best" but this is a generalisation and one tube manufacturer's 6500K tube can differ greatly in spectral output (the important factor) from another manufacturers. I know this from experience and comparing spectrum graphs.
I have had excellent results with a massive range in temps. from 3000K up to 14000K. As long as the tube has most of its light output in the red part of the spectrum and a little in the blue part then most tubes will do fine. Unsuitable tubes are mainly ones which are designed for marine set-ups which have a large proportion of blue light (especially actinic - designed to stimulate coral and macro-algae growth). These will cause algae growth in a freshwater set-up with a few exceptions.
There are expensive tubes designed specifically for plant growth that do perform better than common normal output tubes but good results can be acheived with standard, commonly available types. In summary most tubes will grow plants as long as there is enough light produced. Mixing types is a good idea this will increase the likelyhood of reaching the plant's light requirements. Good reflectors are a must.
With any type of tube though you will get algae unless you keep a balance. More light needs more CO2 and nutrients. Less light needs less CO2 and nutrients. You WILL get algae eventually unless you plant heavily IME. I have never seen a tank that is lightly planted (less than 40% substrate coverage) and lit for 10 to 12 hours that does not experience an algae problem sooner or later. A guaranteed way to avoid algae is to plant at least 70% of your substrate with fast growers, inject lots of CO2 (25 to 30ppm) if you have above 2 WPG (even if you don't it will help) and keep the water fertilised. Nutrient-rich substrates help but are not essential if you keep your water fertilised (possible exception with Echinodorus and Cryptocoryne species - these need nutrients to the roots to get them going). Algae's biggest enemy is growing plants.
Some may not agree entirely with what I have written - it is subjective and based on my personal experiences. I hope it provides some usefulness nevertheless.
IMO too much emphasis is placed on colour temp. (K). Unfortunately one cannot know from this figure alone how effective the light produced will be for plant's photosynthetic requirements. It is widely regarded that between 5500K and 6700K is the "best" but this is a generalisation and one tube manufacturer's 6500K tube can differ greatly in spectral output (the important factor) from another manufacturers. I know this from experience and comparing spectrum graphs.
I have had excellent results with a massive range in temps. from 3000K up to 14000K. As long as the tube has most of its light output in the red part of the spectrum and a little in the blue part then most tubes will do fine. Unsuitable tubes are mainly ones which are designed for marine set-ups which have a large proportion of blue light (especially actinic - designed to stimulate coral and macro-algae growth). These will cause algae growth in a freshwater set-up with a few exceptions.
There are expensive tubes designed specifically for plant growth that do perform better than common normal output tubes but good results can be acheived with standard, commonly available types. In summary most tubes will grow plants as long as there is enough light produced. Mixing types is a good idea this will increase the likelyhood of reaching the plant's light requirements. Good reflectors are a must.
With any type of tube though you will get algae unless you keep a balance. More light needs more CO2 and nutrients. Less light needs less CO2 and nutrients. You WILL get algae eventually unless you plant heavily IME. I have never seen a tank that is lightly planted (less than 40% substrate coverage) and lit for 10 to 12 hours that does not experience an algae problem sooner or later. A guaranteed way to avoid algae is to plant at least 70% of your substrate with fast growers, inject lots of CO2 (25 to 30ppm) if you have above 2 WPG (even if you don't it will help) and keep the water fertilised. Nutrient-rich substrates help but are not essential if you keep your water fertilised (possible exception with Echinodorus and Cryptocoryne species - these need nutrients to the roots to get them going). Algae's biggest enemy is growing plants.
Some may not agree entirely with what I have written - it is subjective and based on my personal experiences. I hope it provides some usefulness nevertheless.
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