Is it about time to change the T5 light bulbs? Par meter readings
 

It has been 9 months since I switched to the ATI 10 x 54W T5 powermodule. I believe it is about time to change the light bulbs. Before I change the new light bulbs. I would like to record the par reading in my tank. Hopefully it will help me to decide when is the right time to replace the new T5 bulbs. Also I can compare the par difference between new and old bulbs. I will post the full tank par reading every month. If you happen to have a par meter at hand, you're more than welcome to chime in.
This is not a T5 Q&A thread, please do not ask me "deep" questions. I just like to put some data and numbers together, and it might be interesting?

Here is my tank spec.
Size: 60 x 30 x 24(H) Euro-braced
Lighting: ATI Powermodule 10 x 54W, hanging 5 inches from water level
Lightbulbs 9 months old
T5 combination: front to back
Blue+
Aqublue spec.
Blue+
GE 6500 K
Blue+
Aqusun
Aquablue spec.
Blue+
Aqusun
Blue+

9 months is probably a little early but if you want peak performance probably about right.

http://i43.photobucket.com/albums/e3...ym/ATItank.jpg
ATI 10 x 54W 5 inches from water level

http://i43.photobucket.com/albums/e3...m/Parmeter.jpg
Apogee par meter

http://i43.photobucket.com/albums/e3.../parsensor.jpg
A plastic stick hold the light sensor tied with rubber band

http://i43.photobucket.com/albums/e3...-09002-1-1.jpg
The number on the top of the tank is par readings the center of light fixture at water level

The photo period is 11 hrs for 2 blue+ and 9 hrs for the rest of the bulbs.

I purchased the par meter 3 months after ATI powermodule installed. I started hanging the fixture at 10 inches above water level. The par reading at center of water level is 950 (3 months old T5 bulbs). Three months later (6 months old T5 bulbs), the par reading at the same center of water level dropped to 720 drammatically. So I decided to lower the fixture to 5 inches above the water level. The par reading was back to 950. Ever since, the par at the center of water level always stays around 950.

The tank is 60" wide, and the fixture is 46" wide. So your edge readings of 510 and 580 are not directly under the bulbs?

No, the par number at both ends without light cover is only about 30 to 50. 510 and 580 are measured directly under the ends of light fixture.

The par readings does not look too bad at 9 months old. When will you think it is time to replace with new bulbs? The par number or coral growth?

Man, that is a sweet tank!

WOW! Nice tank.

Watch for the color. The spectrum of the lamps shifts with age. Guys in europe were changing lamps at about 8 months because after 9 they noticed a change in color but at that time they didn't have the good reflectors or active cooling so they were really pushing things.

Your PAR numbers still look high enough BUT how much do you want to shock the corals when you do put new lamps in? You don't want to let them get so weak it is a huge shock when you do change them, One thing you could do is put a new blue plus in and compare the look to an existing lamp. If there is a big difference I would go ahead and relamp. If not let it go a month and check again.

When you do decide to change lamps I would do 1 a day so you aren't hitting the corals with additional light all at once.

Actually, before ATI T5, I was running 2x 400w MH reeflux 10,000k in LB reflectors. I got incredible growth. Most of my sps doubled or tripled the size in 6 months. Due to the space limitation, I was not able to hang the reflectors higher, and the corals don't look very happy in color and PE. After switched to T5, the growth rate slows down, but more PE and color pops.
I will start hanging the fixture 10 inches above the water level again, and move it down later after par drops. Be honest, that fixture is very heavy, I don't know if I can move it down once a day to replace one light bulbs. I will check my workers comp. policy before I make my move.

That is a good idea. I will take your advice and wait for another month or months. Thank you for the compliment.

Thank you for the nice words

Does 4 ft T5 light fixture can cover 5 ft tank?
I have par reading at both ends not directly covered by T5 lamps. The tank has euro-bracing 4 inches glass plate at both side. I keep some low light sps, but one of the stag on the right side turns brown in color.

http://i43.photobucket.com/albums/e3.../ATItank-1.jpg

very nice tank!

Amazing tank. Do you have a build thread with any info?

where in california are you?

Yeah what he said. /\ /\ /\

You arent going to get enough PAR at the ends to keep high light critters there. I use a 4 foot fixture over a 5 foot tank and the ends obviously aren't a intense as the rest.

So it looks like the t5's aren't living up to their "hype". Over 20% loss of par in 3 months. This is pretty common with flourecent bulbs, I never thought t5's would be any different....

Depends on the system, My 80 watt Ice Cap system had better than 80% of the new PAR after over a year. Ultra Solaris was down about 30% after 7 months but part of that was due tio the crappy reflectors getting screwed from salt spray.

Thank you, maynardjames, snaza.
You can find my tank thread here: http://www.cvreefers.org/showthread.php?t=12942

I am in Modesto

I bought the par meter 3 months after ATI T5. So I have no idea what is the par reading with brand new lamps. The par decreased 20% in 3 months is for lamps between 3 months old to 6 months old. I noticed the growth rate slowed down a little bit at that time and that's why I checked the par value.

I also change the fan speed from 4.5v to 9v 4 months ago. It might also help to keep the par with cooler lamps.