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Put lower kelvin bulbs on my tank - what a difference it makes!

1K views 11 replies 9 participants last post by  leros 
#1 ·
I always had to push my tank really hard to get my plants to pearl. It took rigorous dosing of ferts and extremely high CO2 levels to get my plants to pearl just a little bit.

I had 2 10,000 K bulbs. I had been told that 10,000 K was just as good for plants as lower kelvin bulbs and I prefer the whiter look of 10,000 K.

I had been neglecting my tank for a few months. I had not dosed any ferts and my CO2 ran out. The first thing I did was replace my bulbs with a 6000K bulb and a 5700K bulb. To my surprise, my plants started pearling. Even without ferts or CO2, they were pearling more than I've ever seen before.

Now than I'm dosing ferts and using CO2, they're pearling like crazy. Not to mention, I'm finally getting red coloration out of plants that I've only been able to get to grow green leaves. I've been missing out. I can't wait to try some of the plants that I've had trouble with in the past. :smile:
 
#10 ·
I think every time I have measured PAR with warm white vs cool white bulbs, the warm white ones gave more PAR for the same wattage bulbs. I don't know the reason for this, but the difference was easy to see. Combine that with the improved PAR from newer bulbs, and that might be the reason for the better growth.
 
#11 ·
10000K vs 6500K tells us how bulbs will look to our human eyes, but it doesn't say much about the spectrum of light that plants need to photosynthesize. Two bulbs at 10000K can be made up of different spectrums, which is why in the reef world people obsess over manufacturers' spectrum charts, and worry over the age of their bulbs because the spectrum changes with use. At least for corals, some 10000K bulbs are better than others, and T5 tubes are replaced frequently (every 6-12 months).

I'm a former coral keeper trying my hand in planted freshwater, and it's my observation (not proof) that it's easier to find good PAR from 6500K bulbs than 10000K, and bulb age is not as big an issue. That can explain the PAR readings that Hoppy found.

You could combine bulbs as someone else said if you want the bluer look, or look into the higher regarded reef bulbs like ATI to see if they make a difference.
 
#12 ·
I highly suspect that my new bulbs are better quality so the PAR rating is very likely to be better.

The old bulbs were Hamilton Technology 10,000K Super Daylight bulbs (here). Unfortunately, I couldn't find any spec sheets for these so I can't compare.

My new bulbs are both Deltec Giesemann. One is a AquaFlora 5700K (here)and the other is a Midday 6000K (here). Despite the Kevlin ratings being so close, they put out very different lights. The AquaFlora puts out pink light and the Midday puts out a greenish white light.
 
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