t5 or m/halide

[lenny]

hi at the moment i have on my 5x2x2 tank a twin 250 watt metal haylide 14000k bulbs. i have also just bought a t5 luminaire 4 tube 60" jobby. 320 watt. what i was wondering was has any one gone from m/h to t5,s with any success. i keep sps corals so would hate to loose them buy doing it. any advise veiws ect. lenny

[pipsreef]

Hi Lenny
Dont do it T5's just havn't got umph in them to keep sps's unless of course you put lots of them, but that will be defeating the object.
You could always fit the T5's as well as the Halides and possibly alternate them during the day with timers simulating cloudy weather.

Happy Reefkeeping

Andy

[roge21]

Hi i use 8x 80w t5s on my 6x2x2 think yhey are as good as MH just as bright just need to change the tubes regularley.

[wayne in norway]

I've gone the other way.

Lets put it this way, you're dropping 40 % of your wattage, invariably meaning a drop in PAR, and losing your glitter lines. What do you think will happen?

You'll get a lower leccy bill , but I got tired of changing bulbs. And I like glitter lines.

[EnglishReefer]

The only real downside to T5's is the bulb life (though this is supposed to be improving with better tubes and fixtures with fans to control heat build up).

You would prolly need between 6-8 tubes (with individual reflectors for best results) over a 2' wide and 2' deep tank, you wont have as much flexability with sps coral placement (depth wise) or the "glitter" lines but thats not exactly the end of the world.

Light coverage will be a lot better with less dark areas like you get with single light point sources. Theres a lot more scope for mixing and matching tubes to get the colour you want.

When I went T5 I was using less electric in 2 ways - 1 was lower total wattage for the tubes than what I was running halide and tubes and the second was chiller running cost was dramaticly reduced (330w plus feed pump 65w!) - reduced to the point when fans could keep control of the temp.

Have a look at Dananos tank or Bernh Mohr (sorry can spell :-) ) for some stunning results.

HTH

[lenny]

hi my main concern is the corals, health and colour. will going from m/h to t5,s change the colour of the corals or start them to strip ect. always a risk when you change anything to do with lighting ect. yes i know i,ll save a bit on the leccy bill and the cooler will not have to work as hard but ????:confused: dare i try it.

[lenny]

hi andy . what to do????? the old leccy bill is getting harder to pay if you know what i mean. hows the stirrers going. all ok i guess as not heard anything to the contrary. lenny

[roge21]

I run 8x80W T5s 0n my6x2x2 very bright with no probs everything grows very well just change the tubes offten 6-9 mounths

[Glenn@home]

FWIW

The comparison between T5s and Halides is difficult due to the obvious differences in the way they deliver light. At least the comparison should be between similar levels of light output ie. 400watts of t5 vs 400watts of halide.

Even this is not the whole story, but taking this as a starting point then I do not believe that there is a signficant difference between simlar wattages of halide or T5 as long as the output is distributed over the same area.

Clealry this may not be the case but given a high t5 wattage spread over a tank compared with a similar wattage of halides the differences may not be crtical.

One things thats clear from the reading I have done is that light intensity is but only one factor that impacts on the growth and colouration of sps.

JMHO

Glenn

[Tony B]

There's loads of 'proof' that T5s work, some examples mentioned already, fishermans frags only use T5s, just look at how bright his corals are.

Apparently the Germans are massive fans of T5s.

Although, I use halides at the moment, I will be adding 4 T5s later this year too boost the light.

Always a good subject to talk about though!

[Glenn@home]

Tony

I agree t5s work, i used to use them, there are loads of myths and mythinformation about them.

I think the key issue is that if you want to keep critters that require high light intensities then it only matters that the right wavelengths in the right doses are provided.

From a practical viewpoint if I were to start a tank again I would go with halides as probalby ther easiest and maybe even cheapest way to provide high light intesities.

Having juggled with 8 runs of tubes over my 6x2x2 i can see that halides might have made life simpler.

Re the cost issue, its often assumed that halides are more expensive to run than t5s. If we are comparing similar light outputs, then I doubt this.

The reason is that if i wanted 2 x 500w halide i would have the energy consumed to produce the light plus losses in the starters. With t5s i would have a similar requirement in terms of the energy consumed to produce the light plus the losses from several starters. Maybe these losses would be more than that for a couple of halide starters?

I dont know this for fact, i only know the size of the bills for running 500watts of t5s and they are similar to the reports i see/hear for poeple running halides.

JMHO

Glenn

[EnglishReefer]

Does depend what ballasts you are using, most if not all of the current T5 (eletronic) ballasts are pretty good.

Old style halide ballasts are quite ineffecient - as much as 10% if I remember right.

Agreed halides are the easy option both in installation and maintence, I am fairly convinced that heat transfer or water warming effects are much more pronounced with halides though possably due to higher IR outputs.

FWIW

[Glenn@home]

ER

As I said its only a hunch re the costs/losses, all i know is that my t5 starters ran pretty hot, too hot to touch comofortably, and to me that suggests high losses in electrical efficiency but I couldnt quantify it.

Im not certain about the heating effects, i know halides have this rep, but i never used them. my t5 tubes were too hot to touch, even to the tune of leaving slight burns on exposed flesh when reaching inside the tank if i wasnt careful.

I had a closed hood and always found heat a problem with my t5s, offset by use of fans in the hood.

I think that both light sources have their benifits and drawbacks but would be cautious about choosing one over the other on a single issue since both can give rise to similar problems depending on how they are used.

JMHO

Glenn

[EnglishReefer]

ER

I think that both light sources have their benifits and drawbacks but would be cautious about choosing one over the other on a single issue since both can give rise to similar problems depending on how they are used.

JMHO

Glenn


Couldnt agree more :)

[waterfalls]

For the moment lets assume that control gear losses are similar.
Lets say you save 500W-320W= 180W per hour. This is 0.18kWper hour. The cost of electricty is about 8 pence per kW hour.
Saving per hour is 0.18x8p=1.44 pence
Assume lighting is on for 10 hours a day. So the savings per day is 14.4 pence per day. Over six months the savings will be 14.4x180days= £25.92 pence.
How much will you spend to replace the tubes in six months time?

HTH in deciding if you are saving money or not.

But if you really want to be exact then total looses of two T5 twin 80W control gear will be 342W compared with total losses on 2x250MH will be 550W

[Glenn@home]

I am not sure if they are available now, but all i could ever get was single controls for 80w tubes, meaning that I would have six controllers for 480watts t5.

Intersting subject, i think whichever way you cut it if you want lots of light it costs regardless of the source.

Glenn

[waterfalls]

Glen
The twin 80W control gears are available now. It is much cheaper to buy a twin unit then two single ones. It should only cost marginally more then a single unit.

Dhiru

[kim]

I am fairly convinced that heat transfer or water warming effects are much more pronounced with halides though possably due to higher IR outputs.

I suspect that the IR outputs of T5s and halides are pretty much the same...their efficiencies (lumens or PAR per watt) are well matched, and the rest is likely to be IR. Dhiru, does that make sense ?

My guess is that the more diffuse light (and therefore more diffuse IR) pattern of a T5 relative to a halide is responsible. The IR radiation will be absorbed in the first few millimeters of the tank water. In the case of halides, where the IR is very intense under the lamp, the heat will be quickly transmitted down into the tank because of the high local temperature at the hot spot and relatively high thermal conductivity of water.

T5s don't give these hot spots....so I think that while the total heat output is the same, the rate of transmission of this heat from the water's surface down into the tank will be slower, giving the surface water a chance to evaporate and carry away that heat before it is carried into the tank.

Water has the highest thermal conductivity of any liquid (ie the rate of heat transfer between a "hot" and a "cold" spot is greater than for any other liquid). It's weird stuff, and this weirdness could be the culprit, rather than different amounts of IR.

Okay, a little off-topic.....but it's fun to speculate ! :D

kim

[EnglishReefer]

:) I love this place sometimes, I'm sure NASA are spying:D

Kim

I think there was an article in one of the monthly internet publications about localised heating and IR from light sources a long while ago - was quite an interesting read esp about corals under high output IR light sources having a much higher temperature than their surrounding water (possably leading to unexplained coral losses), if I ever bump into it again I'll post up a link.


Sorry to Lenny for going off the rails a tad :D

[Pip]

FWIW, I have a 4x2x2. I used to have 6xt5's with reflectors under the hood..... and that was tight. My Heteractis malu nennie started to shrivel up (after a few months). So I bought a 2nd hand arcadia twin 250mh, changed the lamps, and within weeks nennie picked up and began to flourish. I couldn't have added anymore t5's under my hood.... so I would've been stuck with 324 watts. tube replacement every 9 months approx £120. MH replacement every 9 months approx £90. Over a year I reckon its about even on the money side (lamp/tube replacement + leccy bill), adding another 2x t5's may have made it slightly dearer to run (t5's versus MH) but would still only have supplied 432 watts against the 500 MH.

Just my groats worth,

Pip

[waterfalls]

IRR will follow the same rules as visible light. So totally agreee with your summation about heating water.

Dhiru

[Glenn@home]

FWIW the only problem i see with the hypothosis about the heating is that water in a reef tank is far from static and so the primary mechanism for heat transer from the surface waters is not conduction but mechanical mixing.

Therefore the rate of heat transfer through the body by conduction is less important that the mxing of the water.

Since heat transfer by radiation is measured per unit area the rate may be different at a given point between halides and t5s, but if the percentage of IRR given out is the same (we did say if?) then the total heat flux will be the same, hence the heating problem will be more or less equal throughto the tank. We should also remeber that we are talking about a timed exporusre to the IRR ie a rate so the exposure period will influence the temp rise. although how much im not sure but of course this concept does form the basis of cooling sstems for many applications.

it is worth noting that heat losses by evapouration is a function of the temperature of the liquid, the temp and the humidty of the air, plus the air velocity over the surface.

Therefore if a halide does increase the temp at a given spot signficanlty compared with a t5, then it is feasible that the rate of evapouration will be signifcnalty higher. i suspect the differences are small, say parts of a degree bearing in mind the turnover rates for reef tanks.

JMHO

Glenn

PS reminds me of why i like UR even though i no longer have a reef.

[lenny]

:) I love this place sometimes, I'm sure NASA are spying:D

Kim

I think there was an article in one of the monthly internet publications about localised heating and IR from light sources a long while ago - was quite an interesting read esp about corals under high output IR light sources having a much higher temperature than their surrounding water (possably leading to unexplained coral losses), if I ever bump into it again I'll post up a link.


Sorry to Lenny for going off the rails a tad :Ddon,t worry about me i decided ages back to stick with my m/h and just add two t5,s as well. interesting post though.lenny