[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

Lux Meter Readings

Hello Folks:
     I finally got around using my new lux meter which I purchased from pets
wharehouse on someones recommendation from our list.  I got the $99.00
dollar model.  I did some quick measurements just to start getting a feeling
for what was happening with the florescent lighting from my Phase IV hood. 
I played with the sensor in the water and noticed that if I tilted the
sensor so that it was not at flat and level with the hood the readings
varied.  I opted to simply maneuver the sensor until I could get the highest
reading it was able to get on the lux meter.  
     I put in 4 new Hagen 20 watt bulbs.  Two of them were Power Glo and the
other two were Aqua Glo. My hood has a thin plastic shield to protect the
tubes.  I took my measurements from the surface of this plastic shielding
and moved down into the water.

80 watts of lighting in one hood.
7000 lux = #1  I put the meter up against the clear plastic shield that
protects the florescent tubes.  Phase IV is at 5.5 inches above
the water surface.

2540 lux = #2  My first reading was at 12 in. from the the plastic shield or
6.5 in. underwater.

1440 lux = #3  My second reading was at 18 in. or 12.5 in under water.

Does anyone know what values are ideal in terms of lux.  We always talk in
terms of watts.  My readings are not "scientific" because there are so many
variables that will affect the amount of light intensity that can reach the
bottom.  I took readings #2 and #3 with the hood hanging over the floor and
got readings of #2 = 3930 lux and #3 = 229 lux.

Hood suspended  5.5 inches above water surface  for a total of 80 watts.

Readings directly at plastic shield on hood   7000 lux 

Readings in the water (12 in from hood) =   2540 lux       1440 lux

Readings out of water (18 in from hood) =   3930 lux       2290 lux

I know that others have been taking readings and concerning themselves with
reflectivity in the aquarium and from the hood reflectors.  But my concern
is what kind of light intensity is needed by the plants and is minimal or
optimal for the various species. My reflectivity inside the tank I know is
diminished by algea growth on the glass.  

I took similar readings from my old florescents which I replaced.  These
Sylvannia bulbs T-8.  They were 7 months old and each one was 18 watts.  Two
of the bulbs were Growlux, one was an AquaStar, and the other a LuxlinePlus.
These bulbs were only 23-10 lux less than my new bulbs.  Pretty good
considering age and wattage differences.  So I have stored them on standby
and will see what I get for the Hagen's in 7 months.

In case someone was interested in comparing figures and setting up a better
test situation let me know.

Thanks, Diana

Say Bye to Slow Internet!