MH light intensity

[bessycerka]

Is there a meter designed for reading the correct amount of light under the water, something a photographers light meter? There must be a trick/shortcut to know if there's too much or too little light for specific coral / actinaria types..... If you have the versatility of a pendant light, it can be raised or lowered to vary the light's intensity, so you can adjust depending on what the organism's requirements are. My rationale is that if you have a 400 watt MH pendant light ( and don't care about the light spilling into the room ) it should be versatile enough to provide the correct amount of for any depth of water, and any type of animal's requirements. 400 watts instead of having 150 or 250 watts, and learning later that it's not cutting it, or changing the light system over to a different tank size, or species, then running into problems. Are there any very experienced reefkeepers out there with any comments? Are there wavelength/spectrum issues to consider also? Thanks....

 

[wangotango]

I guess a lux or par meter (not exactly sure what they're called) can tell you the PAR you're getting in the water.
I think I see the point you're making about hanging the pendant up higher, but it's kind of silly to run a 400w halide two feet up over a 20" deep tank. There are guidlines to follow; a 175w is good for up to about 20", 250w, upto about 24"-30" (depending on what you're keeping), and 400w for tanks over 30" deep.
Is that what you were looking for?
-Justin

 

[perfectdark]

It would be a PAR Meter and they are very expensive. But the measure the intensity of your light at different depths.

 

[bessycerka]

Yes, the meter............It would be silly to have a 400 watter up 2 feet in the air, I agree. The thing is, right now we're setting up tank after tank, different sizes and depths, I want to be able to have clams, and SPS ( waiting for some tanks to age a little more ) and also want the ability to supply light for frag tanks, so moving pendants around seems the only option right now. I don't want to bleach out lower light coral and actinaria in the meantime. Now I'll have to hunt down a meter, thanks.......

 

[reefraff]

Apogee-inst.com sells Meters. Their Quantum PAR meter with remote sensor runs around 250 bux.
The wattage of halide lamp needed depends on how tall your tank is, what you want to raise, the color temp of light you want to run and the particular reflector or pendant you plan to use. A 250 watt XM 10K lamp using a PFO M80 ballast in a Sunlight Supply Lumenmax pendant will blow away a 400 watt 20K lamp mounted in a cheap reflector.

 

[nycbob]

the doctor site sells a lux meter for $90 made by milwalkee.

 

[frankthetank]

I hear everyone talk about the doctor site... I never know what it is.

 

[acrylic51]

You'd want a PAR meter and they aren't that cheap as opposed to a lux meter......you'll find them around $500+

 

[scsinet]

Check with your local reef club. Reef clubs often purchase them for the club members to share. I know our reef club has a really nice one. Never used it though.
Of course you'll have to join to use it.

 

[bessycerka]

thanks all for the great feedback, I have some good ideas now