PAR Observation - ATI T5 after 10 Months

[jjencek]

I got myself an Apex PAR meter and was wondering what my T5s were doing after 10 months of using them 8 hours per day. Here is what I found out comparing them to a new set ...

The lights are part of the fan cooled build-in top of the Red Sea 250 tank. They are 39W and here is the layout.

------------------ ATI Blue Plus ------------------
------------------ ATI Coral Plus ------------------
------------------ ATI Aqua Blue Special ------------
------------------ ATI Aqua Blue Special ------------
------------------ ATI Coral Plus ------------------
------------------ ATI Blue Plus ------------------

I measured the PAR right at the clear plastic cover at 15 different spots. Here are the numbers of the NEW lights:

1214 1406 1326 1323 1073
1246 1425 1438 1396 1272
1115 1272 1228 1256 1079

And here are the numbers after 10 months 8 hours per day:

760 961 804 820 747
840 891 955 923 766
683 641 648 648 472

So here is how much PAR I lost after 10 months:

-37.40% -31.65% -39.37% -38.02% -30.38%
-32.58% -37.47% -33.59% -33.88% -39.78%
-38.74% -49.61% -47.23% -48.41% -56.26%

I also measured the differences at a few spots inside my DT and the loss was about 30%.

My personal conclusion:
Maybe I should change the lights more often.

[2una]

Yeah they probably fall off pretty quick as even with those hood fans running i'd put money its not keeping it cool enough in there..I'd guess that would be why.
Interesting info tho.
At least with the 250 they did put some cooling there,With the 650 that's a joke as it relies solely on passive cooling from just aluminium on top the light unit. When i took that original 650 unit off & replaced it with a ati sunpower i doubled my par(using the same tubes but 2 less).

[jjencek]

Originally Posted by 2una

Yeah they probably fall off pretty quick as even with those hood fans running i'd put money its not keeping it cool enough in there..I'd guess that would be why.
Interesting info tho.
At least with the 250 they did put some cooling there,With the 650 that's a joke as it relies solely on passive cooling from just aluminium on top the light unit. When i took that original 650 unit off & replaced it with a ati sunpower i doubled my par(using the same tubes but 2 less).

Are you saying what I think you are saying that just cooling them down increased the PAR?

[2una]

Originally Posted by jjencek

Are you saying what I think you are saying that just cooling them down increased the PAR?

Yep - if they are running too hot yes
I proved that to myself with my 650, if i put fans over the aluminium "heatsink" i could watch the par increase by 60-70 units

[E.intheC]

Did you use the same par meter each time? (new bulbs vs 10 month old bulbs?)

[Fredfish]

Did you do an initial burn in before the first measurement?

From what I remember there is an initial drop in output over the first 100 hours until the lamp 'stabilizes'. Output numbers provided by manufacturers are measured after the burn in period.

[jjencek]

Originally Posted by E.intheC

Did you use the same par meter each time? (new bulbs vs 10 month old bulbs?)

Yes, I used the same PAR meter. I actually did it all in the same day period. I measured the 10 months old lights first and then replaced them with the new ones and measured those.

[jjencek]

Originally Posted by Fredfish

Did you do an initial burn in before the first measurement?

From what I remember there is an initial drop in output over the first 100 hours until the lamp 'stabilizes'. Output numbers provided by manufacturers are measured after the burn in period.

Interesting. I did not know that. I will recheck the numbers after 100 hours.

[LQT]

Looks like the effectiveness of the cooling system of the fixture plays a big role in T5 bulb life. Not sure if you saw this, but BRS did a video on T5 par loss over time of several different bulbs when run in an ATI Sunpower fixture.

[alton]

It seems the perfect way to use T5HO's is to use an ATI fixture with dimming ballast. Setting it up to where 70% max still gives you enough PAR on the first day. And then checking your PAR each month and having the ability to raise the percentage to maintain your PAR levels for a couple years and not changing your lamps every 8 months.

[solitude127]

Could you post your PAR reading after 100 hours? I bet those will be closer to what you were seeing at 10 months.

[jjencek]

Originally Posted by solitude127

Could you post your PAR reading after 100 hours? I bet those will be closer to what you were seeing at 10 months.

I plan to do that and post them here.

[alton]

When using MH, the lamps where brighter at 100 hours than day 1. Not sure about Fluorescent?

[jjencek]

Ok, here are the results after 100 hours ....

Here are the numbers of the NEW lights (zero hours):

1214 1406 1326 1323 1073
1246 1425 1438 1396 1272
1115 1272 1228 1256 1079

And here are the numbers after 100 hours 8 hours per day:

939 1096 1000 984 836
884 1054 1067 958 891
724 910 891 801 654

So here is how much PAR I lost after 100 hours:

-22.65% -22.05% -24.59% -25.62% -22.09%
-29.05% -26.04% -25.80% -31.38% -29.95%
-35.07% -28.46% -27.44% -36.23% -39.39%

[jjencek]

So in other words. Don't compare new T5 lights out of the box with your old lights. Wait for 100 hours and then compare. Here is how those numbers compared in my case ....

Here are the numbers of the NEW lights after 100 hours:

939 1096 1000 984 836
884 1054 1067 958 891
724 910 891 801 654

And here are the numbers after 10 months 8 hours per day:

760 961 804 820 747
840 891 955 923 766
683 641 648 648 472


So here is how much PAR I lost after 10 months:

-19.06% -12.32% -19.60% -16.67% -10.65%
-4.98% -15.46% -10.50% -3.65% -14.03%
-5.66% -29.56% -27.27% -19.10% -27.83%

[solitude127]

wow, that's a huge difference between new bulbs and 10 month old bulbs. Usually when I change out bulbs, I'll change them all out at once and the cut my photoperiod in 1/2 and slowly ramp up until I'm back to my normal schedule.

Thank you for the comparison.

[nereefpat]

Very interesting. Thanks for posting this.