T5 poor par readings

[dropped]

I recently bought two T5 fixtures, they were dirty cheap which might be the answer to the following question.

 

I also bought the following t5 bulbs

• 2x Giesemann Aquablue Coral (WHITE) Ultralife T5
• 2x Giesemann Super Actinic Ultralife T5

 

I installed two of the bulbs into the fixture and turned them on and tested par straight away with my seneye par meter, the results were as follows

 

1CM away from the bulb par was 400

Anything further than 10 away from the bulb was 18 par.

 

Is this expected with cheap T5 drivers?

[jedimasterben]

Yep.

 

 

 

Though it's more about the reflector than anything.

[RayWhisperer]

Ballasts do make a difference. The best ballasts I found were the Phillips Advance ballasts, however, they only really did better when actively cooled. That was many years ago, though. So, I'm sure newer technology has pushed that to the wayside.

 

However, as the young Jedi pointed out, it's more the reflectors, than anything else.

[dropped]

Yep.

 

 

 

Though it's more about the reflector than anything.

 

 

Ballasts do make a difference. The best ballasts I found were the Phillips Advance ballasts, however, they only really did better when actively cooled. That was many years ago, though. So, I'm sure newer technology has pushed that to the wayside.

 

However, as the young Jedi pointed out, it's more the reflectors, than anything else.

 

surely in this case its the ballast? shouldnt be dropping 390 par in 10cm lol

[braaap]

 

 

 

surely in this case its the ballast? shouldnt be dropping 390 par in 10cm lol

 

 

Nope. In this case it really is reflectors. They direct the light into the tank. Poor reflectors scatter it or absorb it not direct it into your tank.

[dropped]

I cant put this down to solely the reflector. as par drops off to 18 at a distance of 10cm from the bulb. must have something to do with the driver as well.

[evilc66]

Agreed. It's a combination of both. Many cheap fixtures have very bad ballasts that will have a ballast factor under 0.9 (meaning, they are underdriving the bulb). Odyssea is notorious for this, but they aren't alone.

[dropped]

So where i am i have very limited access to T5 fixtures.

 

So as that is the case, I picked up a Hagen glo t5 54watt retro kit & matching reflectors (Pic below)

 

 

However PAR has not improved.. could it be the bulbs? bad batch?

[dropped]

I emailed the vendor i got the bulbs off, this was their response from gieseman. Kind of makes sense i guess.

 

With your customers meter, it will work well under a point-source such as LED (or metal halide etc), but holding under a diffuse light source such as a fluorescent tube, it cannot capture the light emitted along the entire length of the tube, and the longer the tube, the more complex the procedure to measure the total light output. So what we are saying is that the total output of the tube cannot be measured by holding a small sensor under a portion of the tube.

 

If your customer mounted the sensor some metres away so that the entire length of the tube was irradiating the sensor, then did the calculations to allow for the diffusion over that distance (inverse square law), and reflection of light, it could be worked out. Another (rough – as the internal emissions of the tube on surrounding phosphors will skew the results) way of looking at it is to measure the width of the sensor, then shutter off the sides, so that the sensor can only see light (at 30cm in this case), from a length of the tube that is the same as the width of the sensor. Call that length ‘Ln’, then multiply the result by the number of units of Ln required to make up the entire emitting length of the tube.

[jedimasterben]

Yeah, that's not how that works at all lol.

[gus6464]

Is the sensor of the seneye dirty? Think we might be missing the obvious here.

[CronicReefer]

Definitely clean the sensor very well before use and make sure you hold it completely horizontal. Any tilt can have a major effect on the seneye reading. I found mine to be extremely accurate throughout the tank and distance as long as the sensor was cleaned well.

[dropped]

Yeah, that's not how that works at all lol.

 

i thought the same but......... second guessed myself once reading that.

 

Is the sensor of the seneye dirty? Think we might be missing the obvious here.

 

Bran new seneye, not kept in the tank, dried and stored in a draw when not in use. Its pretty dam clean.

 

Definitely clean the sensor very well before use and make sure you hold it completely horizontal. Any tilt can have a major effect on the seneye reading. I found mine to be extremely accurate throughout the tank and distance as long as the sensor was cleaned well.

 

 

I also have a radion xr30 pro on the same tank, it reads par perfectly from the radion.

 

So are we calling BS on the response from the vendor??

[evilc66]

Of course it's BS. PAR, and any other light measurement is a spot reading. Doesn't matter what the light source is. You can take multiple readings over an area and average them for PAR over X area, but it's still spot readings.

 

If the reflector changed nothing (within reason), then the ballast is the next culprit. You haven't told us what brand theses fixtures are yet. Care to divulge?

[dropped]

Yea post #8 says i changed the ballasts to hagen -glo 54 watt

[evilc66]

Oh. I assumed you just used the reflectors.

 

Not to ask an obvious question, but did you remove the protective film from the reflector surface (if it had one, some do)?

[dropped]

Oh. I assumed you just used the reflectors.

 

Not to ask an obvious question, but did you remove the protective film from the reflector surface (if it had one, some do)?

 

Hehe yip i removed them.

 

have you used theses lights before?

[evilc66]

I've used T5's but not that particular set of reflectors and ballasts.

 

It's still entirely possible that it's the ballast at fault. One quick way to check would be to put a watt meter (like a Kill-a-Watt) on it and see what the power draw is. On a two bulb system, you should be reading about 110-120W at the wall. If it's reading less than 110W, then the ballast is underdriving the bulbs.