1oK/6700 bulbs

Do these promote.. lets say hair algae growth?

 

Good or bad idea?

 

if the bulbs are old/bad they will
usually the things to check for first are phosphates and high nitrates, also check the water you use to top-off for phosphates before adding it to the tank
sometimes if you have enough algae the tests on the tank will return a result of 0 phos because the algae is eating it all so there is no traces of it but it still exists in some fashion to feed the algae

 

I'm just trying to decide whether to go from 6700k/10k and a 460/420 to two 10k/460 bulbs.

 

are you using CF lighting or VHO?

 

PC lighting

 

if you have corals or are planning on having corals 6700k is near worthless imo

I'd run 10k or 12k for white, and have an equal amount of 460nm

 

6700k is actually the closest to the suns spectrum. Most people don't like this spectrum because it's very yellow as is sunlight but on the downside the 6700k bulb does promote HA growth IME. The good thing about 10,000K is its really close to the suns spectrum but isn't as bad at promoting algae growth.

see this url
http://csep10.phys.utk.edu/astr162/lect/sun/spectrum.html

 

I use 14k and 420nm in actinics.

 

If only that were available for my fixture!