150 watt and 250 watt DE in the same fixture?

[vresor]

Not at the same time of course, but based on the ads below it looks like only a ballast change is required to convert this Sunlight Lumen Max 3 pendant from 150 watts to 250 watts. Each lists the Lumen Max 3 as accepting either 150 or 250 watt DE bulbs:

• http://www.aquariumspecialty.com/lumenmax-3-150w-de-reflector
• http://www.readysetreef.com/sunlight-supply-lumen-max-3-de-pendant
• http://www.reefspecialty.com/index....mid=1&option=com_virtuemart&vmcchk=1&Itemid=1
• http://www.horticulturesource.com/product_info.php?products_id=4497

I spent ten minutes looking for the dimensions of DE bulbs and didn't find much (need more than ten minutes!), but I did find this quote from Sanjay's Facts of Light article in Reefkeeping: Double-ended 150-watt lamps use the RSC (RX7s) base, while the 250-watt double-ended lamps use the Fc2 base. The picture below illustrates the differences.

I can appreciate that regulatory authorities tend to create regulations that are very specific, but I can tell you that a 19 mm wrench works on virtually every 3/4" nut. Are the RX7 and FC2 bases just so similar that they can accept either type of bulb?

 

[allsps40]

No you cant put a 250W bulb in a 150W fixture. The 250W bulb is larger in size and has different ends as you can clearly see in the pic.

 

[vresor]

I do clearly see that difference, so why is a reputable manufacturer of metal halide pendants marketing a fixture that will accept either type of bulb? Makes me wonder...

 

[sirreal63]

The description is a poor one, what they are trying to say is it is available in either a 150 or 250 watt, not that one fixture accepts either bulb. SLS made the mistake of assuming that their potential customers already knew that there was a difference.

 

[vresor]

Now that I can believe. I'm trying to hedge my bets with a fixture that would switch from 150 watts to 250 if I discover that 150 isn't enough light over my 20" cube. Looks like that flexibility isn't there in a DE fixture like it is in a Mogul fixture. The relatively small, round 150 watt DE reflector I have now produces enough light, but leaves the corners of the tank dark. I'm committed to a larger square reflector, but can't decide if the extra cost and heat produced by the bigger wattage bulbs is needed (or wanted?). Any insights?

 

[sirreal63]

I am one of the minority that still uses 150's. I have a pair of them lighting a 40x40x17" tank, reflectors are LumenArc III Mini's. The effective lighting area is about 30x30 and with the right bulb and ballast combination you can have more than enough light for your tank. With only 17" of height, the 150's are all that I need, and the DE reflectors are more compact than SE ones. As you point out, the benefit of the SE is changing wattage is easy, for me I have to change ballasts and sockets, which I do, my fixtures were originally 250 watt, and I have run both wattage's in my LA's. I have modded my fixtures so the socket change is easy, but is not as easy as flipping a switch on the ballast and changing bulbs. 20" is at the point where either will work, you can get as much par with a lower k 150 but you may not like the color. I use Ushio 10k's with EcoXotic LED supplements and like the color and have enough par to bleach sps, prior to the 10k's I was running Radium's, which are just about the perfect bulb for a mix of color and par.

 

[vresor]

My first experience with MH is the stock Current 150 watt bulb. The plan is to decide on a wattage, buy the right Lumen Max 3, the right Galaxy ballast, and the right Phoenix 14K bulb. It's going over a 20" cube Solana all-in-one. The tank loses five inches to the back sump area, so I think a big reflector would end up leaking too much light over the edges of the tank. The Lumen Max 3 is about 11 inches square and should minimize light leakage into the room. In the end, I suppose I am trying to rationalize the lower wattage system. I've really struggled with SPS over the past three years, but a lot of that was water chemistry, not lighting. That said, I'm not trying to grow a SPS dominated reef. 150 or 250?

 

[sirreal63]

You won't have any problems with keeping enough light on them, but if you are running an electronic ballast, go with the 250's. The Phoenix bulb is an HQI bulb intended to be run on a magnetic ballast, the electronic ballast will under drive the bulb, resulting in less par. Not a big deal on the 250, but will be with the 150.

The LM reflector is a spotlight, so you will have a very intense small section directly under the fixture, so coral placement becomes important. If it is going to be a mixed reef, keep the high light acro's directly under the fixture, but it will require some acclimation to keep from bleaching them. If I were going to do this, I would not use the electronic ballast, but the correct M81 ballast and 150's. You will drive the bulb correctly and the difference in electricity is minimal and the difference in par is approximately 15-20%. Either the 150's or the 250's will work, it is a tossup but equipment selection becomes important with the 150's.

 

[vresor]

Thanks Sirreal. Coming from the LED world for the past four years I think I'm predisposed to assume electronic metal halide ballasts are the way to go. Consequently I didn't even consider a magnetic ballast. Are the heat and buzzing noise I've read about real issues? If so, to control those issues I could run the power down through the floor and leave the ballast in the basement below the tank.

How big a difference is there in PAR between a 150 driven by an M81 and a 250 driven by an eBallast like the Galaxy?

 

[sirreal63]

I haven't seen figures for the Phoenix150 , but let's look at the Radium, which has good figures and is also an HQI bulb.
M80 250 watt par of 85
Electronic 250 watt par of 66
M81 150 watt par of 47, this is shielded, as it would be in the fixture, unshielded is 58.

The only real issue with running the HQI, that I know of, is it does change the color, typically it is more blue and some people prefer that. As far as Par is concerned, if you want to go electronic, do it with the 250, not the 150. The 150 is already an underpowered bulb once you get out of the 10k bulbs, the exception being the Radium, which does well but if you don't want any light restrictions, go with the 250. As far as noisy, buzzing magnetic, some of the old ones did that, the newer better designed ones do not have that problem. My M81 only has the fan noise, and that isn't loud at all.