Converting from T8 to T5 lumen question

[Josh Beeston]

Hi everyone,

I'm re-doing my scape, and thought I might upgrade my lighting system at the same time - currently 2 x 20w T8s. I've been looking at the 24w T5s, and my question is this:

Even though the wattages are similar, will the T5s have a higher lumen output?

I can't find much information on each brand/type of tube, lumens doesn't appear to be something they use as a measure, just wattage and kelvin. But if the light output is higher on the T5s, why do we say a plant will grow at e.g. 0.5w per L? Surely the watts becomes irrelevant as far as the plant's concerned?

If the light output is different, do you know of a rough conversion rate? So if I swapped from 2 x 20w T8s to 2 x 24w T5s, how much light output/lumen difference could I expect?

Thank you in advance!

Josh

 

[xim]

T5s are newer generation and have better efficiency. So generally they have better lumens per watt than T8s.

Most 18-20w T8s are about 1000-1300 lumens. Most 24w T5HOs are about 1600-1800 lumens.

This guide might be useful. The main unit is lumen.
http://tropica.com/en/guide/make-your-aquarium-a-success/light/

 

[ian_m]

Arcadia 18W T8 is 1000lm and 24W T5 1900 lm so roughly double. Be careful not to melt the plants and/or induce algae with such a jump in lighting.

When I changed my 25W T8 to 35W T5's I rotated the reflectors round to block light for first two weeks, then got impatient and put reflectors in normal position and got slight green algae on glass and on some plants. Whoops.

 

[Josh Beeston]

Ideal - thanks guys! Can you reduce light cycle to avoid melting/algal bloom?

 

[ian_m]

Can you reduce light cycle to avoid melting/algal bloom?

Really best to keep time same as T8 time, but reduce T5 light level by, rotating reflectors, darkened plastic sheet, foil rings on the tubes, one tube on etc. Loads of ways of reducing intensity.

 

[Sudipto]

I don't know if this is too late to respond but the lumen information is generally printed on the packaging. Look at the packaging of my Osram's 24W HO. It mentions 1600 lm at 25 degree celsius. This can vary from brand to brand. More expensive brands will probably emit more lumens for the same 24 watts.

Incidentally, 24 watt is the standard for 2 footer tubes. For 3 footers it is 39 watt and for 4 footers it is 54 watts.