How To You Calculate Your Lighting?

[RobGoldsmith]

Hi
I keep reading what lighting plants and fish need, is there a way in which i can calculate this?

Surely the depth of the tank makes a difference as the light is so much further away?

I have a 30w T8 bulb in a 30ish litre wall aquarium, is there a quick sum i can do?

Thanks
Rob

 

[This Old Spouse]

Hi
I keep reading what lighting plants and fish need, is there a way in which i can calculate this?

Surely the depth of the tank makes a difference as the light is so much further away?

I have a 30w T8 bulb in a 30ish litre wall aquarium, is there a quick sum i can do?

Thanks
Rob

And also what kind? I have "aquarium" bulbs in one tank and they seem too yellow to me.

 

[RobGoldsmith]

30" T8 natural red lamp 20000k

 

[OldMan47]

Calculating your light is easy. A standard T-8 fluorescent is 8 watts per foot so you are looking at 20 watts for a 30 inch tube. You might get to 32 watts if you have a twin 2 foot tube fixture. A 30 litre tank, at about 8 gallons, is a fairly high light level for your 30 watt statement and is plenty for many plants even at the nominal 20 watts. The depth of the tank does indeed play into the equation but a small tank like that will see very little attenuation of the light by the water. Be very careful of using the WPG guidance you find in many places. It is based on the efficiency of T-12 tubes over a 4 foot long tank and can be very misleading for much smaller or much larger tanks.

 

[RobGoldsmith]

thanks

 

[Caprichoso]

Another thing to consider is if your lighting hood has a reflector on it. That can make a little light go a long way.