T5 Par Reading

LAX Noob Reef · Jul 9, 2021

Sell your fixture and get a ATI. I'm running 10 inch above water, 600-700 right below water, and 500 -350 at SPS level, 180-250 at bottom tank.

I'm using 8 bulb ATI 48"

JCM · Jul 9, 2021

LAX Noob Reef said:
Sell your fixture and get a ATI. I'm running 10 inch above water, 600-700 right below water, and 500 -350 at SPS level, 180-250 at bottom tank.

I'm using 8 bulb ATI 48"

Yeah I had an ATI fixture on a previous tank, they are definitely nice. This fixture had good reviews though and the reflectors are supposed to be "97% reflective" or some such, in line with ATI. Do the 24" lamps just not pack as much punch as the 36" or 48"? Obviously they are less powerful, but spread over a smaller area so I thought PAR would be similar regardless of length.

Tamberav · Jul 9, 2021

I am not familiar with this fixture but depending on t5's some have great output of par that the meters can't read. It's not uncommon for actinic may be showing half as much par as it has for example. The par meter may be suspect as I am sure it is hobby grade. Some par meters are better than others. Which one did you use?

Bpb · Jul 9, 2021

That was my original experience when I tested par with my old sunpower. Was getting about 200 par at the top of my rocks with all 8 bulbs firing.

JCM · Jul 9, 2021

Tamberav said:
I am not familiar with this fixture but depending on t5's some have great output of par that the meters can't read. It's not uncommon for actinic may be showing half as much par as it has for example. The par meter may be suspect as I am sure it is hobby grade. Some par meters are better than others. Which one did you use?

Apogee SQ-420 is the model I believe.

JCM · Jul 9, 2021

Bpb said:
That was my original experience when I tested par with my old sunpower. Was getting about 200 par at the top of my rocks with all 8 bulbs firing.

I was really surprised with the numbers. I know from experience T5's can grow wonderfully. This is my first experience with 24" lamps though, so I wasn't sure if that was the problem.

Tamberav · Jul 9, 2021

JCM said:
I was really surprised with the numbers. I know from experience T5's can grow wonderfully. This is my first experience with 24" lamps though, so I wasn't sure if that was the problem.

It seems that par meter drops off in the 400-450nm range. Which ofc the actinic and blue plus bulbs have plenty of. I would also expect t5's to read lower then led's

The par meter is certainly reading lower than actual, can't say if it is something to be concerned about. Age of bulbs will matter as well as how good the fixture is at cooling the bulbs and ofc the distance of your fixture above the water, the clarity of your water and so on.

I do have my T5's the same length as my tanks so can't comment on the drop off. I have a 24 inch 4 bulb ATI but it is over a 24 inch long frag tank. It certainly works well though!

Again, no idea with your fixture but there is decades of tanks/evidence that t5 grows acropora.

JCM · Jul 9, 2021

Tamberav said:
It seems that par meter drops off in the 400-450nm range. Which ofc the actinic and blue plus bulbs have plenty of. I would also expect t5's to read lower then led's

The par meter is certainly reading lower than actual, can't say if it is something to be concerned about. Age of bulbs will matter as well as how good the fixture is at cooling the bulbs and ofc the distance of your fixture above the water, the clarity of your water and so on.

I do have my T5's the same length as my tanks so can't comment on the drop off. I have a 24 inch 4 bulb ATI but it is over a 24 inch long frag tank. It certainly works well though!

Again, no idea with your fixture but there is decades of tanks/evidence that t5 grows acropora.

Thank you, that is reassuring. The bulbs are all about 4 months old and the fixture is 9 inches off the water. The fixture also has 2 strong fans cooling the lamps.

I agree, I have used T5's successfully for years but never a 24" fixture and I've never actually measured the PAR before. I'll stick with it and see how things grow. Everything looks healthy and colorful but growth hasn't really taken off yet. To be fair, the tank is pretty new though.

Bpb · Jul 9, 2021

JCM said:
I was really surprised with the numbers. I know from experience T5's can grow wonderfully. This is my first experience with 24" lamps though, so I wasn't sure if that was the problem.

My guess would be the tarnished reflectors and crazing on the acrylic was perhaps the culprit

Pico bam · Jul 9, 2021

I have an 36" 8 bulb ATI over my lowboy 50 gallon 48"x24"x10". I seriously find best results with only 2 bulbs running! Its most likely just the shallowness of my aquarium but t5's are stronger than you think. Now if you want to go all sps you might consider more par but I don't think the numbers are terrible. Especially with the above statement on accuracy of the par meter.

JCM · Jul 9, 2021

Pico bam said:
I have an 36" 8 bulb ATI over my lowboy 50 gallon 48"x24"x10". I seriously find best results with only 2 bulbs running! Its most likely just the shallowness of my aquarium but t5's are stronger than you think. Now if you want to go all sps you might consider more par but I don't think the numbers are terrible. Especially with the above statement on accuracy of the par meter.

It's definitely not all SPS, only across the top of the rocks. Mostly LPS in the rest of the tank.

oreo54 · Jul 9, 2021

JCM said:
So I borrowed a PAR meter from a friend and took some measurements in my tank. I tried to create one of those fancy pictures with all the numbers but it didn't come out as nice as most that I see. My tank is 36" x 21" x 20" and I'm using a 6x24" Pacific Sun Althea T5 fixture. Bulb combo is

3x blue plus
1x aquablue special
1x true actinic
1x GE 6500k

These reading were with all bulbs on. Honestly, I am pretty disappointed with the readings. I knew they would dive hard on the ends with the 24" fixture over the 36" tank but even directly under the fixture they are low. I thought they would be twice this under the lamps.

This is an old picture, many corals have been added since but it was the best straight on picture I could easily find. The birdsnest has grown quite a bit but other acro's, while colorful are not growing much at all. Guess it's time to rethink lighting?

It is what it is.
Get a fixture that fits the tank better.

LED Lamp - Althea T5 - Pacific Sun EU

LED Lamp - Althea T5. Ultra efficient cooling via the inbuilt 120mm low speed fans keep the ballasts and tubes working at optimal performance.

pacific-sun.eu

Ones small thing...it may actually be cooling your tubes too much (and make sure the tubes are in on the right side, writing under the fans I believe)
Too bad, looks like a fun fixture

JCM · Jul 9, 2021

oreo5457 said:
It is what it is.
Get a fixture that fits the tank better.

LED Lamp - Althea T5 - Pacific Sun EU

LED Lamp - Althea T5. Ultra efficient cooling via the inbuilt 120mm low speed fans keep the ballasts and tubes working at optimal performance.

pacific-sun.eu

Ones small thing...it may actually be cooling your tubes too much (and make sure the tubes are in on the right side, writing under the fans I believe)
Too bad, looks like a fun fixture

That's the one. I thought it would fit the tank well when I bought it. I don't keep any demanding corals on the ends so I didn't think it would be a problem. That's interesting about overcooling, I'll look into that and the bulb placement. I had no idea there was a right orientation. Thanks

Tamberav · Jul 9, 2021

ah ya.. good catch. With ATI the label of the bulb needs to be under the reflector side that has a hole so air travels correctly. There are certainly a lot of little details that went into some of these fixtures to make sure they are running tip top that we don't know about (unless we read the manual?). I considered other fixtures but just went with ATI since I trust they know whats up.

JCM · Jul 9, 2021

Tamberav said:
ah ya.. good catch. With ATI the label of the bulb needs to be under the reflector side that has a hole so air travels correctly. There are certainly a lot of little details that went into some of these fixtures to make sure they are running tip top that we don't know about (unless we read the manual?). I considered other fixtures but just went with ATI since I trust they know whats up.

I had no idea! I just checked, half my bulbs are oriented correctly. I'll fix the other 3 after lights out tonight and retest tomorrow.