Pure power of PAR or PAR/time?

[MisterP]

My question is about the aspect of raw PAR value and time. Should we be shooting for a pure power number or does this change with time?

Say I provided 200 PAR for 8 hours or 350 PAR for 4.5 hours and I'll fictiously call this something like PAR*hour, like Ampere*hour, where the two fictious numbers multiplied together are the same PAR*hour.

I ask because I have changed reflectors on my halide and still don't have great PAR values. I only get about 220 at the surface on a 16" deep tank from a 150 HQI Radium on M81 ballast.

Would I be able to just extend my photo period and meet the needs and color up the corals?

 

[sirreal63]

You should be getting a lot more than that, a whole lot more. Are you still using the Bimini or did you go with something else? I know you had questions before on the actual meter, and I think it is having an issue.

 

[MisterP]

I have the Hamilton Cayman Sun still with the M81 and Radium bulb.

 

[MisterP]

I replaced the battery in the Apogee and still only get like 200 par about 11" from the light.

 

[MisterP]

Its frustrating cause I figured after upgrading I should be able to get 400+ at the surface.

 

[sirreal63]

Way too low, I would test it with someone else's tank. You should be hitting around 800 at the surface. I will PM you a link to the testing I did with the 150 Radium, 10K XDE with M81 and LumenArc Mini, which is pretty equal to your Cayman Sun.

 

[rovster]

Carmen sun is a nice reflector, I have one, with a 250 radium I'm getting 350 at the bottom of my tank and up to 700 in some hotspots close to the glass. I agree there has to be something wrong with your meter.

 

[MisterP]

Rovster, How high off the surface is your light and how deep is your tank?

Is that par number with any supplementals or just the MH?

 

[MisterP]

Could the ballast or bulb be an issue? The bulb is only 3 months old and the ballast is new from Hamilton, it's the 150 HQI they send with the package. Is it possible it's not a true M81 and it's under driving it?

 

[sirreal63]

It is possible, but I doubt it is a ballast or bulb issue, even an electronic ballast will do way better than that.

 

[rovster]

Reflector is 10" off the water. Blue led supplement. Tank I think is 17" deep?

 

[MisterP]

So you're getting 700 at the surface?

I think I'm just going to forget the reading until I can verify it. Obviously if you get 700 with the 250W I should be closer to 400 with 150W, I suspect.

 

[trueblackpercula]

Just want to mention that a 20k bulb will give off les par then a 14k bulb. What are you running?

 

[ssscuz]

That does seem low but I will try keep on topic.
I have tried to extend a lower par rating light. It didn't help as much as upgrading the light.
It's still like trying to keep coral under a huge sunshade in the ocean.

Are you trying to get 400w halide results with a 150? Maybe upgrade to a 250?

 

[MisterP]

Well my tank is only 20 gal and 16" deep so I figured the 150 W would be good.

The bulb is a Radium which is better par wise than about anything 14k and up.

I'm doing 8 hour photoperiod but in the future go to a 250 W mogul w/ Radium. I just hate to keep getting poor par results and switching lights every 2-3 months. Also I'm worried about the heat a 250 would put off. Right now the 150 brings tank temp from 77.5 to about 80 F, so I imagine the 250 would be closer to 82F.

 

[rovster]

Are you seeing any issues in the tank that would lead you to believe the light is not putting out enough PAR? A 150 should be fine if not overkill in a small tank. I had to install a dual fan on mine because the 250 would raise the water to 5-6 degrees in 4 hours.

 

[MisterP]

No issues other than maybe a pokerstar monti not coloring back up to the nice blue color which I've heared comes with higher light levels.