What MH wattage to buy?

[Recife]

Hi, I'm upgrading to MH but I'm still unsure as to which fixture to buy. My tank is 48" long x 30" deep and I'm considering 2 150w MH + 2 96w PC Actinic.
I've done some reading and some people say this is not enough for a tank this depth. The thing is I'm not interested in clams or sps. I do want an anemone and a couple of lps that I can place on the top half of the tank.
I don't want to seem cheap, but is it really going to be worth going for 2 250MH if I'm not going that many light demanding corals on the bottom?

Please let me know what your experience tells you.

 

[Reefdaddy1]

For 30" tank you really should go 250 watt, 150 will be real dim compared to 250 watt. With a 250 watt you can keep what you want, But a 150 will probably end up killing your LPS. Go with 250 watt 20k that will do it for ya.,

 

[rudeanduncouth]

I have read for tanks over 24" deep you need 400w MH.

 

[Krish]

I run dual 250's and love them...My tank is only 18 deep though

Here's a quote from one of the sponsor's sites regarding wattage with depth. HTH

Metal Halide: This is your most powerful form of lighting. A halide bulb creates an arc of light so bright that it can spread up to a 36" wide tank. It's the closest form of lighting compared to the sun. You can use halide for soft corals, lps, sps and clams. The most common use is for those wanting more sps and clams. Some guidelines are 1 halide bulb for every 2 feet of tank, up to 3 feet. 175watt up to 24" deep, 250watt up to 36" deep, 400watt for deeper tanks. It's very common for hard core reefers to use 400watt on even a small 30 gallon tank. When it comes to sps and clams, they can handle and thrive under intense lighting. With halide, you also need to consider the Kelvin, which is the color temp. 5500K warm white, 6500K warm white, 10K Crisp white to blue tint, 12K-20K blue tint. For mixed reefs, we recommend the 10K bulbs, for sps and clams, we recommend the 65K's. If you go 55-65K, we highly recommend VHO or PC actinics, they will improve the overall color and look of the tank.

 

[Recife]

That's what some sites say, but you can't always trust them.

For anemone keeping, I've seen many posts in this and other forums of people reporting they can successfully keep anemones with PC lights! I also have a friend who has a 30" deep tank who keeps an anemone for over a year on his sand bed. So these guidelines certainly cannot be that rigid.

My point is that I won't put an acropora on the bottom of my tank. Actually, I won't have one in my tank at all. I plan to add mushrooms, brain and tongue corals to the bottom. Anything else will be higher on the tank.
Also, I have a sand bed of 3+ inches, so that alone reduces the depth of the tank.

If 250 MH is strictly necessary I will go for it. I'm just not convinced it is worth the extra mile.

 

[Krish]

That's what some sites say, but you can't always trust them.

Just trying to help...I wish you the best

 

[Reefdaddy1]

Well In my expeierence. I have seen people use whatever is cheapest and pay for it in the end. 150 or 175 watt units are excellant for shallow tanks, But when you get into 24 to 30 inch tanks it does not make any sense to even attempt it. 250 watts you have a clear sense of use and success backing it up. No sense trying something that may work when you know something will work. GARF uses only VHO lighting, But thier tanks also use a 4 to 5 inch sandbed. Thats why they can get away with it. If you going to be running a BB or minimalist bed, then go 250 watt. Its best for all your corals. Also where you put a anenome is not always where its going to stay. So if light is minimal it will move and sting corals as it goes. Also you asked us what our expierence says, to say its not dependable is really asking for no advice at all, So take it for what it is worth, I know for fact LPS will struggle with 150 watts units.

 

[fishermann]

You should have aleast 250's in my opinion and preferrably 400's for 30" deep, because sooner or later you are going to want clams and acros. I have a 230 and a depth of 22" of water and I have mogul based 400's being overdriven with HQI bllast.

 

[reedman]

There is very subjective information out there on lighting...it's a hot topic (pun intended).

"Rules of thumb": The old rule of thumb was that if you were going deeper than 24" use a 400W. Since this came out there have been some great strides in the reflector, bulb, and ballast industries that changed that "rule". Never trust a "Rule".

In most tanks you have some high light critters, some mid light, and some low light. The area right under a MH bulb is a hot spot (high light area). As you go out and down from there you lose intensity. This means if you only have a few animals you want to keep that are high light you could use 250W and just put the high light animals at the top. On the other hand, if you want to keep high light animals at the bottom of the tank then you may want 400W.

Reflectors: These make a HUGE difference in how much bang you get for the buck in MHs. The luminarcs are awesome (though pricey). They have a great spread of light without losing too much intensity. Highly recommend looking into these. If you put these in with 250W lights I think you could keep almost anything you want (except maybe low light animals).

Bulbs/spectrum: The choice of bulb spectrum (Kelvin rating) can have a big impact on what wattage you should select. If you want to run 6500 bulbs you get plenty of intensity (though the color isn't to many people's liking) and as such can go with a lower power ballast. If on the other hand you want that blue look that 20K bulbs give then you really need to increase the wattage to compensate for the lower PAR rating of the bulbs.

Distance from light to animal: How far up do you plan to mount the bulbs? It's not just a matter of tank depth, but the distance from the bulb to the animal.

water clarity: This is often overlooked. If you plan to keep your water crystal clear and have the filtration to do so, then you can back off the power a little (250W instead of 400W). But you have to stay on top of it all the time.

It's not a simply depth based decision...sorry...but I'd rather have you have all the information before you choose something you're not happy with later.

 

[Recife]

Sorry folks, I appreciate the help. I'm just a bit frustrated because most of what I read online or in books is "this is recommended", but I haven't seen many real life experience.

I think you've done enough convincing

 

[reedman]

what I read online or in books is "this is recommended", but I haven't seen many real life experience.

Welcome to reefkeeping

 

[Krish]

Sorry folks, I appreciate the help. I'm just a bit frustrated because most of what I read online or in books is "this is recommended", but I haven't seen many real life experience.

I think you've done enough convincing

One thing you must try to keep in mind with this hobby is what works for one person may not work for the other so I guess that is where guidlines come in to give you an idea of which direction to take. You hear 1-2 inches of fish per gal, but people like me believe in a lot less. Works for me, but maybe not for another. I had an aneone that did well under pc's and then you have anemones that will do well under the brightest form of lighting out there. Just take te sun for example. I live in the Bahamas and see anemones surviving under the sun in 1 ft of water at low tide. 250w IMo, would be the safest way to go and also, something you know will work for basically anything you'd want to keep. I use 20K's so as to not have that extra intensity of lighting and if it weren't for these guys here pushing me to get the 250w dual MH's rather than the 175's I almost got, I would have been highly dissapointed. Here is a link that Scooter showed me earlier this week that will give you some idea as to the different spectrums like Reed explained.

Click on the arrows at the bottom to change the Kelvin rating
http://metricksystem.com/chris/250wcolour/

 

[moortim]

If you do enough looking you will find that most of the people on here that have 30" deep tanks use 400w bulbs. That of course is not what you have to do but is what many people have already done, if you are looking for examples...................

Tim

 

[bradreef]

The thing I dont get is that you are talking about spending more on 250's than 150's that seems backwards to me. 250's are pretty inexpensive at most places.

 

[dragoneggs]

If you do enough looking you will find that most of the people on here that have 30" deep tanks use 400w bulbs. That of course is not what you have to do but is what many people have already done, if you are looking for examples...................

Tim

Ouch! I am starting the design of my lighting for a 60x24x30in deep tank and was thinking of two or three 250 14K MH's. Now it sounds like I need to consider 400s? I am planning for SPS/LPS a few clams and a few fish.

What do you all think?

 

[moortim]

Ouch! I am starting the design of my lighting for a 60x24x30in deep tank and was thinking of two or three 250 14K MH's. Now it sounds like I need to consider 400s? I am planning for SPS/LPS a few clams and a few fish.

What do you all think?

IMO consider the 400's yes, but you are not restricted to them.

 

[dragoneggs]

IMO consider the 400's yes, but you are not restricted to them.

Would you go with 3 250s or 2 400s or (i can hardly say it...) 3 400s???

 

[Scooterman]

Also consider 400w lamps if your using a 15K & above because you loose lots of par after 10k.

 

[moortim]

Would you go with 3 250s or 2 400s or (i can hardly say it...) 3 400s???

I am only speaking from what I have learned not from personal experience, I have never done this myself. I would like someone elses input to confirm what I am saying but it depends on what you plan on keeping and where you want to put them in your tank. You say you want to do sps and clams, do you want them on the bottom? IMO you will want 400w, if you are going to localize them near the surface under the lights then 250w should be fine. I would do 400's myself just because I love lots of light and I would have more freedom of where to put things. This is also my opinion but on a 5 foot tank I don't think you would need 3 400's, maybe 3 250's. Keep in mind these are all just recommendations from someone who has never actually done it.

Tim

 

[dragoneggs]

Also consider 400w lamps if your using a 15K & above because you loose lots of par after 10k.

Aha! Good point I noticed the PAR but didn't think about that too much. I am kind of liking the 14K color.

sorry to jack this thread but...

What kind of spread do you get with the MH? I am sure this is a function of the reflectors but I guess my real question is spacing of the lamps? If the tank is 60in long is two enough with significant dark areas?