double ended mh bulbs vs screw in type
 

hi, whats the difference with the double ended bulbs and screw in type.
a guy at j&l suggested a double ended unit but warned me that they dont stock too many bulbs.
is there benefits of double ended?

thanks for the help

post
 

I am told the double ended ones put off a lot more light than the single ended ones

Usually the DE bulbs seem to give off brighter or more light because the reflectors designed for them are much more efficient at reflecting the light back into the tank than most reflectors made for single ended bulbs.

Re: post
 

nope they don't. a DE actually puts out less light over the same area but because of the size they can have reflectors that are designed to concentrate the light over a smaller area giving the appearance of more light.

If you are stuck for room they are the ones to use. but you can buy the HQI ballasts and drive the screw in ones also as I do. this way if you go 250 watt you can run any screw in bulb out there that is 250 watt on a HQI ballast.

Steve

For the same brand of bulb, HQI does put out more light per watt, and conversely generates less heat per watt. I've been told that this is a feature of bulb design, and has to do with the fact that current passes over the bulb coils in a single direction without having to be looped back like in a mogul. The end result is less resistance at the bulb and higher output.

To look at a "real" scenario, compare the XM 20k double ended vs 20k mogul bulbs. Using the same HQI ballast, the DE bulb generates more light. This demonstrates that the increase in intensity is a function of the bulb, not the ballast.

link


(sorry for the long link)

Edit: I have modified the link so that it shows up as smaller. If you click on it, it is the same URL, but this way it doesn't bugger up the thread width. -Tony

Um, in that link, the SE bulb had the higher PPFD with 79 while the DE bulb had only 55. Doesn't that mean the SE bulb has more light in whatever test that was?

Its a myth that DE lamps produce more light than SE lamps.

"Comparing the data here and other 250W DE articles with the data for 250W Mogul lamps, should provide enough factual information to dispel the myth that 250W DE lamps produce more light output than the 250W single ended mogul lamps. A general sweeping statement to this effect cannot be made, and depends on the lamp under consideration"

http://www.advancedaquarist.com/issu...04/reviewb.htm

One thing I do notice is that my arm use to get red from working on my tank when I had my DE fixture. Now, that I switched to a SE setup, I don't get these sunburns anymore after working under the light for hours.
My DE sytem might have been giving off more UV (even though there was a glass shield).

Sorry you were lied to. I though that also but then I tested the output of my HQI driven SE 10000K AB set up against Sams HQI DE 10000K AB and even with the reflectors on I got a higher PAR output from my set up, this got me thinking.

Steve

Something is spreading this thread way out wide making it hard to read.

I am upgrading a 175W single ended to 250W, and was thinking of getting an HQI pendant to replace the SE pendant, but if there is no advantage would I just get a new ballast and bulb. :question: It would be about $300.00 less expensive. :rolleyes:

I fixed the thread width issue, hope that helps.

But those were different ballasts. You had the high powered M80 whereas mine was using only 250W. :smile:

But yeah, I checked out Sanjay's link there with Coralvue bulbs and the Coralvue SE bulb also had higher PPFD than the Coralvue DE bulb using the same ballast and same color temp bulb.

http://www.reeflightinginfo.arvixe.com/select2lamp.php

but my point was they were both sold as HQI ballast. yours was an electronic ballast which at the time we though were just as powerfull but now we know different. at anyrate lots of data shows that with out reflectors the SE is a more powerfull bulb.

Steve

my next question is what would you recommend for a 44g pentagon shape
tank, total depth is 23" from the top. would 175watts be enough?
or go with the hqi 250w?

thanks
rob

But Steve, if you're mixing and matching like that, what if you had a DE and I had an SE? Your DE on the M80 would still outperform my SE on the IceCap ballast. So in that case one might think that the DE was better. But in fact, you used a different ballast which would produce more light than the IceCap regardless of bulb type. That's why you have to keep the ballast constant when making comparisons of bulb types (with same color temp).

Enough for what?

I'm pretty sure the 250W would be better. If you use a DO meter to test photosynthesis (oxygen output), I'm almost sure that you would have higher DO with the 250W bulb. In other words, the extra light is not being wasted and is being used for additional photosynthesis. That's the case in my tank anyways which is full of photosynthetic animals.

And it goes without saying that all this depends on what you want to keep. If you aren't keeping anything very light demanding, then the 175W is probably enough.

um there were the same color temp weren't they.

Steve

Yes, they were as far as I know. 10K AB.

ok had me confused for a sec.. not hard to do these days it seams :rolleyes: :mrgreen:

Steve

Not entirely. For example, comparing a radium SE to an XM DE shows that the SE bulb gives off more light. But within a given brand, it's most often the case that DE bulbs produce more light than SE at the same wattage. This is the case with XM lights and also true for Sun Aquatics lights with the exception of the 10k series.

Try formulating intra-brand comparisons with sanjay's data to verify that this is true.
http://www.reeflightinginfo.arvixe.com/select2lamp.php

By this data, the myth seems to be that the "rule" for DE vs SE is true for all bulbs in all cases. More accurately, it is a simple general guideline for a given brand name that has some exceptions.

[quote="Samw"]Enough for what?

I'm pretty sure the 250W would be better. If you use a DO meter to test photosynthesis (oxygen output), I'm almost sure that you would have higher DO with the 250W bulb. In other words, the extra light is not being wasted and is being used for additional photosynthesis. That's the case in my tank anyways which is full of photosynthetic animals.

And it goes without saying that all this depends on what you want to keep. If you aren't keeping anything very light demanding, then the 175W is probably enough.



thanks for the input, but i'm still puzzled as to which way to go, with the se or de for a pendant light setup. j&l recommend a de but indicated they didn't carry many bulbs for them. will getting new bulbs be an issue for the de?
thoughts on remote ballast vs Built in ventilated ballast
thanks
rob

If you look at the graph that you quoted in your first message, you will see that the XM SE produced more light than the XM DE. The same goes with Coravue lamps. The same goes for AB lamps. The same goes with Ushio.

The myth is that DE produces more light than SE bulbs and the data shows it. I'm not the only one saying its a myth. I quoted it from Sanjay's website that you are asking me to look at. The numbers show the SE lamps having higher PPFD. Even your example shows the the SE bulb of the same brand (XM) has higher PPFD.

Here are some random comparisons of same color bulbs from same manufacturers using same ballast. It shows that SE is significantly brighter. I can go on but this is time consuming. The first one is from your own link. It doesn't look like the DE is brighter as you say it is when I look at that same graph. And in most of these graphs, the DE isn't even shielded. Once you shield them (like they normally are), the PPFD goes down even more. So, it looks like for the same brand and color, SE bulbs are brighter than DE bulbs in general with a few exceptions.


http://www.hyperdream.com/~samw/temp/xm20k.JPG

http://www.hyperdream.com/~samw/temp/ab10k.JPG

http://www.hyperdream.com/~samw/temp/ushio10k.JPG

http://www.hyperdream.com/~samw/temp/coralvue10k.JPG[/img]

http://www.hyperdream.com/~samw/temp/sunaq10k.JPG[/img]

thanks Sam, that page wouldn't work for me.

Steve

What are your needs? Do you need to save space? If so, get the DE. If not, get the SE. SE is cheaper. The DE system does have a glass shield so if you are placing the light close to the water surface, you don't need to worry about water splashing on the bulb.

PPFD isn't the same as intensity though, and many of those graphs do tell a tell of increased intensity given off by DE bulbs. PPFD is the most typically used index for photosynthesis because it occupies regions of the action spectrum for chlorophyll. A higher PPFD rating is not the same as saying that a bulb is more intense.

Um I thought we were talking about higher light output all together as in PAR or usable light. why would I care if a light is more intense if its PAR is lower? doesn't make sense. the big selling point of DE's by any store is they make more money selling them. first you spend a lot for the housing 446.00 as apposed for a reflector, socket, cord at 150.00 for a SE bulb and then the replacment bulbs are a higher cost for something that requires less material and manufacturing to produce, so I imagine the profit margin is higher.

Steve

Zooxanthellae use a number of mechanisms not available to plants to harness light energy from other portions of the spectrum. These include, but are not limited to UV-A rays, and are responsible for the rich coloration you see on your corals.

If we were only concerned with the PPFD over the PAR region, then we might be tempted to think that 6500k Iwasakis (189 PPFD @ PAR) are more desirable than 20k Radiums (85 PPFD @ PAR). Try it out for yourself, and you'd find that the corals under the Iwasakis generate xanthophyll pigments to protect themselves from the heat transmitted by higher wavelengths. These give off a rust brown color however, and we tend not to prefer this "look" on our corals. (Though do use lower temperature bulbs on the grounds that the corals receive more PAR light.)

This is why when I argue that DE bulbs generally give off more light, I only speak of raw intensity. Its final effect on coral growth, presentation, or other subjective visual tastes are a completely separate matter to me.

So when you asked us to look at this graph in your first post, what are we looking at here that shows DE gives off more light?

http://www.hyperdream.com/~samw/temp/xm20k.JPG

What are you using to measure intensity? I always thought Iwasakis were more intense which is why growth was faster under them.

So are you saying that Sanjay is wrong when he said "Comparing the data here and other 250W DE articles with the data for 250W Mogul lamps, should provide enough factual information to dispel the myth that 250W DE lamps produce more light output than the 250W single ended mogul lamps."

http://www.advancedaquarist.com/issu...04/reviewb.htm

so one could conclude the coralvue and ushio have the most output?

your missing the point. PPFD is another measurment reading of PAR.. they are the same. and I have seen Iwasaki tanks just as colorfull as radium tanks, and I have seen radium tanks just as brown as other tanks. takes a lot more than just light to make color, and light won't make real color on its own.

Steve

I think you're misunderstanding mine and Dr. Joshi's argument. He is saying that it is a myth that DE bulbs are always brighter than SE bulbs, whereas I am saying that it is still a good general rule for bulbs within a given brand, despite a few exceptions like that one.

He didn't use the word "always". That wouldn't make any sense. In studies like this, I've never read or heard anyone say that DE bulbs are always brighter than SE bulbs. What people normally say is that DE bulbs are generally brighter than SE bulbs. This is the myth (according to Sanjay). It is quite simple, all Sanjay is simply saying is that its a myth to think that DE bulbs are brighter than SE bulbs. IF he wanted to say "It is a myth to think that DE bulbs are always brighter", then he would have said it. But he didn't. What he is saying is that its a myth that DE bulbs are generally brighter than SE bulbs because his data shows that SE bulbs are generally brighter than their DE counterparts.

And that XM graph is not an exception. It seems to be the rule. Did you see the other 5 random graphs? They have the same results. Can you tell me again how you measure intensity? You haven't even shown 1 graph yet where the SHIELDED DE bulb of the same brand is brighter than the SE bulb. There might be 1 or 2 but they aren't easy to find. I haven't found it for 250W ballasts yet. I'm sure if I spend another 10 minutes, I might find one.

http://www.reefcentral.com/forums/sh...e+and+brighter

So here, 1 out of 14 tests had the DE as being brighter. Note that these are UNSHIELDED DE tests. Normally, the DE output would be even lower under regular applications (due to the glass shield). Its hard for me to believe that DE's are generally brighter when only 1 out of 14 have higher output and that 1 DE that was higher was unshielded even. When the DE's are shielded, all 14 SE bulbs are brighter.

http://www.hyperdream.com/~samw/temp/37042SE_vs_DE.jpg

http://www.hyperdream.com/~samw/temp..._vs_DE_M80.jpg

Hey Steve. Are you using Firefox or Mozilla or using a MAC? :lol: Apparently, the page only works under IE on Windows. If you are using IE, did you select the wattage listbox first?

http://www.reefs.org/phpBB2/viewtopi...306&highlight=

BTW: Doesn't anyone else besides Brainvat, Steve and myself have a position on this? What about some of the other veterans??? The data shows that SE bulbs are generally brighter. Is the data wrong? Do the graphs lie? Is PAR not a good measure of light output or intensity? What is better than or more relevant to corals than the measure of PAR or PPFD. Are there any links at all with data from research that shows DE's of the same brand are generally brighter than SE's given the same color temp and ballast?

Could people start jumping in and verify that I am not blind here and that the graphs and data on the website do indeed indicate that the SE's tested had higher light output than their DE counterparts? Am I out to lunch cause everyone else is awfully quiet. I am constantly rechecking the data and graphs thinking that I am reading it wrong since someone keeps telling me that the DE's are brighter based on the data on that website.

.

this whole thing got started with the 150 watt DE, putting out a higher PAR level than a 400 watt SE. this was Sanjay's first test of them and the reason was he used a mini pendant for the DE and a bare bulb for the SE. so the DE had the benefit of a reflector. What he later found out is the reflector design of the DE was such that it caused a more intense output in a small area. so in essence it was better at focusing the light. the problem was that the light over a 2x2 section was lower than normal except for the smaller focal spot. When they started testing the bulbs with no reflectors then they found the SE bulbs put out more PAR/Light than a DE which only makes sense if you look at the shape and design of the bulb.

Steve

I been bash many time for this Steve :mrgreen:

I know it since long time SE are supperior bulb in any way but...it's more paying to sell DE.

Ho! By the way magnetic ballast are the best :mrgreen:

Can someone translate that for me please ? :confused:

I have just bought HQI ballasts and am trying to keep up. :biggrin:

hey Stephane, good to see you again.

Steve

HI Steve

The store and French forum board take a lot of my time but when I have couple of minute I came here read a bit wath happen in the Ouest

See you