Odyssea 20" T5HO Fixture Review

This is a repost from Nano-Reef

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Well, seeing as Aquatraders is selling the 20" 4x18W T5HO fixture for the low price of $50, I had to see what the unit was all about.


Initial impressions were mixed. Obviously, I was liking the price. The unit was packaged well, safely double boxed, and wrapped in bubble wrap. I didn't take any pictures of the packaging.

So here is the general fixture

The housing is built well, much like many Odyssea products. The reflector is flat as a pancake, and not all that shiny. The fixture came with two "daylight" bulbs and two actinics, and two 2x18W ballasts to drive them.

I'm not liking the bent wire mounting legs. It puts the fixture way too close to the tank for comfort. With a vice, or a good set of pliers, the mount could be bent to make the fixture higher off the tank, at the expense of adjustment range. It works though, and fits a wide range of tanks. Now, they say it's a 20" fixture, but you will have a hard time fitting this fixture on a 20" tank without resting the fixture right on the rim of the tank. 21" is about the practical minimum if you want to use the legs. Not the end of the world.

The moonlights are one of the high points in the fixture. The color is decent, and pretty consistant between each LED, which is a first for Odyssea. Fluorescence is good, and the overall brightness is just enough, and not too overpowering.

So far so good, until I started to look closer.

This isn't that bad, but it certainly makes me nervous. The end caps are polystyrene, and not ceramic,  polycarbonate, or any other material that is commonly used in the lighting industry. If everything runs the way it's supposed to, they will be fine. If they overheat, or short, they will catch fire, as they aren't self extinguishing.

My next issue is the ballasts. The first thing you notice as you pick them up is that they weigh nothing. Anyone who is into PC building knows that the first sign of a good quality power supply is it's weight.

Not much in there huh? This is not a smart ballast. It's little more than a very basic switching power supply, which isn't that good. First, it's voltage driven, not current driven like it should be. The ballast is designed to output a fixed voltage, regardless of the bulb connected to it. Much like LEDs, fluorescents should be current driven to get the most out of them. Second, there is no protection from shorts (other than a fuse on the input side), over current, or end of life failure, which is standard on most ballasts. Third, it's not particularly efficient. Fourth, there is no programmed start feature, meaning it takes an age for the bulbs to warm up.

Wattage draw on each ballast was about 30W on a Kill-a-Watt. Now, that's two bulbs connected to it. I'd be willing to bet that each bulb is drawing no more than 13W after you factor in "ballast" losses. Somewhat expected based on Odyssea's track record.

Ok, on to performance...

I ended up taking measurements at 18" from the fixture. PAR wasn't too bad actually. I ended up getting a peak PAR reading of 50 once everything was warmed up. Now, that doesn't sound like much, but considering the ballast issues, it's not bad. I even compared them to our 18" UVL T5s, and only managed to score another 10 PAR.

Here is the breakdown, with spectral plots!

This is 50 PAR at 18". Color isn't that great overall. It's quite green/cyan, and is due to the daylight bulb.

This is the daylight bulb. You can see the typical green spike, but there is a big fat cyan bubble that is really killing the color. Only 20 PAR out of these guys (two bulbs).

The blues look a lot better. The color is actually pretty decent, with a nice rich blue. PAR is on par with the UVL 454's at 30. The UVL's do much better as the wattage increases.

Here are the UVL graphs. I used Actinic Whites and 454's. If I had Indigo Suns, the PAR would have been higher.

All on (60 PAR)

Actinic White (30 PAR)

454 (30 PAR)

I want to do some followup PAR measurements that use the spectrometer to get some comparisons that are a little more accurate than the Apogee meter I was using. I'll post them up soon when I get a chance to take them.

So, what's the moral of the story? You get what you pay for. The fixture is ok. The reflector is crap. The ballasts are questionable, but the bulbs aren't too bad, especially the actinic blue. I'm sure it will be fine for a shallow tank for someone on a budget, but if your tank is any deeper than 12" and you want to keep more than softies, you may want to look elsewhere.