T5 for a 27 inch deep tank

Which MH manufacturer do you work for? ;D

I'm just joking, there are reasons to use both type of lighting, and a lot of it is down to personal preference (light/dark spots, shimmer, bulb choices etc). However T5's do actually perform well in tanks over 18" deep, it's been proven time and time again with PAR meters. When was the last time you looked into T5 performance numbers?

 

right, like i said on paper t5s are ALMOST as good as mh... but they still underperform watt for watt and if ur comparing 20k mh to a mix of 10k and 420/460 t5 then yeah the t5s may outperform esp at shallower depths.

but ceteris paribis, mh outperforms t5 slightly... and when u get into 250/400w fixtures the difference becomes pretty significant...

take people who grow plants hydroponically indoors.... t5s are far less efficient and incapable of matching the growth of high powered hid lighting.

we usually consider aestheics more in an aquarium setting and here is where i think mh really shines... no pun intended.

mh provides a distinct crisp and natural looking light that no fluorescent will ever be able to duplicate. period. so even considering that for most aquarists they can and do get more han adequate light intensity from t5s even for the most demqnding corals... its still just not as good... its still a compromise.

 

I have T5s on a 24" deep 120. I feel very comfortable with putting almost any coral in my tank. I am not positive about a clam on the SB. Im not going to say anything negative about MH lights because I have never ran them. I do like the shimmer effect of the MH i do not get that w/ T5s. I would go to some different LFS and look at their tanks and pick what type of lighting look based on the corals that you would like to keep. My LFS runs both type of lights on their tanks. When I was looking at buying my light I was told that they would not recommend them for 30" deep tanks. If you keep most of your SPS corals towards the top and your Softies towards the bottom I dont think you would go wrong with T5s JMO

 

OMG not another T5 vs MH thread!

I have a 23 inch deep tank lit with a 6x54W NEP. It's so bright I need to shade my clove polyps on the sand bed otherwise they refuse to open. I have a Maxima clam on the sand bed (I know supposed to be on a rock but always falls off) that is growing well.

It boils down to personal preference:
If you want shimmering go with MH.
If you want bright spots under the MH and shadier spots off to the sides go with MH.
If you want an evenly lit tank go with T5s.
If power consumption is a concern go with T5s.
If you're concerned about heating your water and needing a chiller go withT5s.
The rest is personal preference. Go to your LFS and compare tanks lit by both. Personally staring at a shimmering tank at the LFS hurt my eyes. It looks cool but after a while my eyes got tired. I could stare at my T5 lit tank all day and my eyes never get tired.

Make your own choices based on your own preference. There is no right or wrong answer.

As far as the OP's question. I think T5s on a 27" deep tank will be fine. You may need to keep softies at the bottom and keep the SPS in the top half.

 

WTB source?

You seem to have VERY strong opinions about lighting you have never had. I'm sure when you upgraded the PC fixture on your nano to a MH the results were great. Thats no reason for bashing T5's all over the lighting forums when you have 0 first hand experience with them.

~Will.

 

Without continuing this too far or getting this deeper into the MH vs T5 debate I would like to point a few things out in your post... Terrestrial plants are different than corals on a few levels.

Plants, for the most part are accustomed to FAR greater levels of PAR... Annectodtally, in the summer even in WI, when I took the quatum out in the sun, I was getting levels of over 1600 uMol/m2/sec... NO ONE has that in a tank. Corals would bleach very quickly. Land plants get this for hours a day, sometimes more.
Some corals do get blasted with ~1000uMols for an hour or sometimes a couple but there is also times it is cloudy or stormy or the water is turbid or the crashing of waves creates blankets of microbubbles that shield the coral.
Most SPS in the wild grow in the area of ~300uMols/m2/sec. Many photosaturate in the 500-600s and will photoinhibit a little more than that. Obviously there is a lot of variances montis will photosaturate and inhibit in FAR lower levels than say acro formosas or other stags.

Also terrestrial plants like warmer spectrums WHICH MH is far better at creating than T5, just like T5 is FAR better at creating bluer spectrums.

People that grow plants(legal or not) use a combination of HPS and MH lights do due the spectrum and coverage. If you can use a 1000w lamp have it 6' above the plants and cover a 6'x6' square or evem greater you will use that as compared to T5... BUT look at SLS, they make Tek but they also make a handful of T5 units gear solely for the terrestrial plant grower. Also T5 is in its infancy whereas MH has been around for decades, its like any other technology.. Thats like saying VHS is never going to get pushed aside by stupid DVDs... Well, thats interesting as VHS barely exist anymore.

Also like stated, how is it a compromise and have you even used T5?

I think I have better growth in my T5 180 with slightly less PAR #s than guys with wasted $ and electricity running MH with higher PAR values....