Lighting Questions

[Pinepages]

My tank is coming along fine. The plants are beginning to grow and the 9 neons seem perfectly happy.
I have 3 x 30W tubes rated 15000k. They came pre-installed.
Are these OK for a 230L (60g) tank?
I read that there should be around 2W / gallon. This would give a figure of 120W and I only have 90W.
What is the effect of taking them down to 6,700k or so?
Is 15000k brighter than say 6,700k? in other words does k relate in any way to brightness.
Are fish adversely affected by bright light?
I do not neccesarily want to chuck them out untill they have given some use.
Many Thanx in advance

[Chrona]

My tank is coming along fine. The plants are beginning to grow and the 9 neons seem perfectly happy.
I have 3 x 30W tubes rated 15000k. They came pre-installed.
Are these OK for a 230L (60g) tank?
I read that there should be around 2W / gallon. This would give a figure of 120W and I only have 90W.
What is the effect of taking them down to 6,700k or so?
Is 15000k brighter than say 6,700k? in other words does k relate in any way to brightness.
Are fish adversely affected by bright light?
I do not neccesarily want to chuck them out untill they have given some use.
Many Thanx in advance

In terms of actual light output, K values has no effect. However, humans see bluer light better, so you percieve 10000k or 15000k as brighter than 4000k, etc. Plants prefer full spectrum light between 5000-10000K. You can try growing plants in 15000k, and it should probably work just ok, but I can't make any guarentees, since you are already a bit low on lighting. I would highly recommend you only attempt low light plants like java fern, anubias, or crypts. Other plants will probably grow as well, but not as well as the low light ones.

Some fish do not like bright lights and prefer to stay in shady spots. I don't believe neon tetras are one of them though. In any case, I don't think 90 watts would be enough to effect them anyways. I'm talking like big compact fluorescent or metal halide fixtures.

[Pinepages]

Thanks Chrona
I have learned a lot from you guys over the past week and am very gratefull.
I am told that my lamps are "multi-spectrum", if there be such a thing. I cannot find the manufacturer on the net.