20K BLV MH bulb versus 14.5K Giesemann bulb Spectrum and PAR difference - Should I change bulbs?

Deep

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I currently run the 20K BLV Nepturion 250W SE bulb over my tank. Couple of months ago I used to run the 14.5K Gisemann bulb. I have measured PAR from both and obviously the 20K bulb has less ( about 100) PAR when compared to the 14.5K bulb. Not too concerned about PAR, but I think growth is slower on the 20K bulbs ( I am not 100 percent about this). I also think certain Acros appreciated the 14k spectrum better. I want to change it back to 14.5k, but worried that the change might cause issues. I am new to MH ( only used LEDs prior to this), so wanted to get some opinions about any ill effects from changing it back ? Will it stunt growth for some time ? Also could you review the spectrum difference ? Is there any use in changing at all given I think the additional PAR on the 14.5K seems to be in the yellow/green wavelengths ?

PAR and spectrum from the Giesemann 14.5K bulb -

IMG_7788.JPG


PAR and spectrum from the 20K BLV Nepturion -

IMG_7789.JPG
 
BRS

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PAR from 20Ks are less than from 14Ks, yes. Choose the speed you want them to grow and stick with that bulb so their growth will be uniform. Changing spectrum and wattage too much all the time will affect the way colonies grow and you don't want to do that. When you change back to the 14Ks start with less hours and then go back to the normal previous photoperiod slowly, then leave it alone. If you like the 14Ks better just do it! Corals will respond do different spectrum in a different way, but they will all do great under halides.
Don't forget that nutrients and other water parameters have tremendous influence on how your corals will behave as well.
Don't look too much to graphics and go crazy about them. Watch your corals and help them to adapt back to the 14Ks, if that's what you want. It is much easier than you think!
BLV is one of the best bulbs ever. Giesemann is also great!
You just can't go wrong with halides. Relax and enjoy the ride!
Post pictures, if you can.
 
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Deep

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PAR from 20Ks are less than from 14Ks, yes. Choose the speed you want them to grow and stick with that bulb so their growth will be uniform. Changing spectrum and wattage too much all the time will affect the way colonies grow and you don't want to do that. When you change back to the 14Ks start with less hours and then go back to the normal previous photoperiod slowly, then leave it alone. If you like the 14Ks better just do it! Corals will respond do different spectrum in a different way, but they will all do great under halides.
Don't forget that nutrients and other water parameters have tremendous influence on how your corals will behave as well.
Don't look too much to graphics and go crazy about them. Watch your corals and help them to adapt back to the 14Ks, if that's what you want. It is much easier than you think!
BLV is one of the best bulbs ever. Giesemann is also great!
You just can't go wrong with halides. Relax and enjoy the ride!
Post pictures, if you can.
Thank you. I will change it back today and reduce the photoperiod like you suggested. Will also post pictures later today. Have a good weekend.
 
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Deep

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Changed it back to 14.5K today and I am so glad I did that. I think I prefer the whiter look.

IMG_8015.JPG


in my hurry to remove the old bulb, I did not wait for it to cool down before trying to remove it with a micro-fibre cloth. Because the bulb was hot some of the fibre got stuck on the bulb and wont come off :( Stupid mistake.

IMG_8018.JPG
 

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I agree the lower kelvin looks so much better for daylight purposes. Deep blue is fine and can be enjoyed for a lengthy part of the day, but daylight looks best when it resembles actual daylight. I was never as happy with the aesthetic of 20k bulbs as I was 10-14k, despite growth being better for me under 20k
 
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