How much light do i need?

[peter1979]

Im thinking of getting a second hand tank with the dimensions

45cm wide x 90cm long x 56cm high

My question is what amount of lighting do i need if i want to go medium to high level and incorporate pressurized CO2, ferts etc and be able to grow most things.

any advice appreciated, cheers
Peter

 

[peter1979]

ive answered my own question, i found an online calculator to give me the volume and working from 2wpg and over i would need 100w or more.
The tank i am looking at has an arcadia overhead luminaire with 2 bulbs in, i will email the seller but any ideas if these thigs can go to 100w with 2 bulbs? or will i need a 3 bulb jobby?

 

[Ajm200]

You should be able to work out the wattage from the type (T5/T8) and length of the bulbs. Each length is a fixed wattage. Also, I believe that rule was used with T12 you probably will need less wattage with more modern and efficient T8/T5 bulbs.

See what this calc suggests: http://www.fitchfamily.com/lighting.html.

You may not need/want all that light at first as lots of light in a new tank with an immature filter (ammonia + high light) can be a great recipe for algae unless everything else is spot on. Does the luminaire have the option to run with just one bulb on at first? If it does you might be better starting with low light levels and gradually increasing after a month or so. You may even find that the plants you want grow fine and fast enough under the lower light levels. Most plants grow perfectly well under lower lighting levels

 

[peter1979]

cheers for the reply. I have jus read the article you linked to, and from what I can see it suggests that i would need around 150w or so.
Also it suggests that for my 25l nano I would need around 59w, which seems crazy overkill. I have 18w on there at the moment and things seem to be going ok. Its got me wondering whether I should up the lighting and see what happens.

cheers

 

[Ajm200]

If you are happy with the nano and your plants are healthy, you may as well leave it as it is. More light means more ferts, co2, growth and maintenance and the potential for an algae outbreak while you are getting the balance right.

I've got 216w T5 over a 500l but only use 108w for most of the time. Everything is growing like crazy even HC Cuba which is supposed to need high light and having to trim the stems weekly. The lower light means that so far (fingers crossed) there has been very little algae. I don't know if I will ever use all 216w for the full photoperiod as the current growth rate is fine.

 

[Garuf]

It's worth mentioning that the fitch guide is just that a very rough guide. Every tank is different and lamps now produce a lot more usable light than they did then. It also doesn't take into account raising the light or the difference between halide and flouro.