T5 question: 3100lm @4000K vs. 2850lm @6500K

Costa

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Hi team,

I am looking at these two T5 lamps from OSRAM

t5.PNG


Do you have any advice on which one to go for? One is only 4000K but gives out more lumen than the 6500K. I understand that plants prefer 6500K but the 4000K one gives more lumen...

Thank you so much
 

ian_m

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Plants use light and don't really care too much about colour temperature.

Your eyes care more than plants do. Choose tubes to make your plants (and fish) look good.

Too lower colour temp and plants look dull & yellow and not bright (4000K and below maybe), too higher temperature and plants look white and washed out (above 10000K).

I have a 8000K white and 6000k "colour" tubes in my tank. Looks too "pink", in my eyes with just 6000K tubes, which is why I added the 8000K tubes. Much better, plants look suitably pop out green and fish, especially cardinal tetras stand out well.

Did you see this thread of tanks with different tubes.
https://www.ukaps.org/forum/threads/cheap-ho-t5-fluorescent-tubes-update-with-photos.555/
 

Costa

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Thank you Ian

Yes I did read through that thread, very useful. I will go for the 6500K then, I guess the 250lm won't make a hell of a difference.

My light unit can carry 8x39 T5HO tubes, so 8X2850lm/800L=28,5lm/L which isn't that bad I suppose... (compared to the cheap ass led I had prior)
 

ian_m

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That's a lot of light, what size is your tank ?

This will help you decide what light level your tank will be running at. High light means CO2, ferts, weekly water changes, daily plant pruning etc.

parforvariousbulbs-jpg.jpg
 

Costa

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Athens, Greece
Thank you Ian,

My tank is 200 x 60 x 60 cm + a 150L sump. Factoring in the substrate volume as well as the media and sponges in the sump, I arrived at a net volume of ca. 800L/190gal

According to this 28lm/L is in the medium light range.

lumen-per-litre-uk_300x218.png


The unit also has reflectors so in theory the output can go as far as 40lm/L, but then again there's a glass cover which will block some of the light.
 
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Costa

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Athens, Greece
I've been reading here that 10,000+ K bulbs are good for planted tanks. Would you guys recommend it?

Asking because I have access to a 15,000K blue ATI bulb (Aquablue Special) and wonder if I could give.it a try or run the risk of algae.

I'm also reading that people are getting a lot of pearling with Actinic bulbs. Do they really work?

Thank you
Costa
 

ian_m

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I've been reading here that 10,000+ K bulbs are good for planted tanks. Would you guys recommend it?
Plants won't care what spectrum/temperature light they get. However a planted tank with 10K+ tubes will look washed out, plants look "bleached" and not very green. This is why people mix say 8K and say 6.5K and even 4K, as these lower temperatures will make the plants look stand out green to your eyes.
 
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