Hi,

Will 4100k PC lamps grow plants well or do I need to get at least 5000k. Asking because our local lighting store carries 4100k 55watt PC's for $10 but the 5000k ones are $25! Is it worth it to pay 2x the price?

Irene

I don't think there's a big difference between 4100k and 5000k. The 4100's will just look a little yellower. Now if you were going from 4100K to something like 6500K, I would pay the extra money because for one thing it will look nicer. I have one 4100k and one 10000K bulb on my 32g and the only difference I can see in my plants is that the sunset hygro doesn't get the really nice red color unless it's under the 10000k bulb. Otherwise all my plants seem to grow the same either way and I don't have any particular algae issues related to the different temperature bulbs.

So, I did go with the 4100k bulbs. They're sort of an ugly pinkish colour. As long as growth isn't affected, it won't bother me though. Any other opinions? When searching the web some people seem to think you do need a k rating over 5000 to grow plants?

Irene

On line they tend to be cheaper, hellolights sells them on sale every so often for about 10-12$ for 55w 8800, 5000K or 6700K which would blend well

Regards,
tom Barr

But is the only issue with k rating the appearance of the tank? It does not affect growth?

I have heard some people say that lower k ratings can increase algae. But personally I think that it will only really increase algae if you already have something else out of whack.

I have one 4100k bulb and one 18000k bulb on my 32g. I don't notice a difference in volume of plant growth or algae between the two areas of lighting, but my sunset hygrophila only gets the nice red color under the 18000k bulb. I'm looking into changing out the 4100k bulb though because the look isn't as nice as I would like it to be, I'm going to go with a 6500 or higher. My water already has tannins in it so with the yellowish tint of the bulb it just makes it look that much worse.

Something else I read, and maybe someone else here knows if this is the case or not - I heard that the k rating is really only the average so to speak of the color spectrum. So just because two different bulbs are, say, 4000k, doesn't mean that they have the same spectrum, and the spectrum is what matters to the plants more so that the k rating. Someone else may be able to explain this better.