# PAR38 bulbs



## Mirkinator (Jan 13, 2014)

Well the color temp is right (6000k), but I dont see any actual par readings, unless that "PAR38" means the PAR at a specific depth, but I couldnt find any specifics on it. Also didnt see any reference to the beam angle. It is 12w so going only off that id give a complete guess that you may need 2-3 of them to cover the whole tank @~23 gallons if you are CO2 injecting and using proper fertz (EI, PPS, etc). If you arent going to inject CO2, you may find it a wee bit strong since its concentrated in one section and most likely only need 1 or 2 (depending on plants, etc). You could possibly raise it.

those are my two cents, but I dont have a lot of experience with those and someone may be able to give you more specifics... Hope it helps


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## chrispowell (Jan 23, 2013)

I will be using pressurised co2 and daily Ei dosing


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## Mirkinator (Jan 13, 2014)

I would think it would work. Just really doubt you will get even close to 2ft of coverage out of one bulb and I think that would be your main problem. The link to the fixture doesnt load for me, not sure if its because im in the states, but couldnt tell how many bulbs it takes or how many you are planning to use.


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## chrispowell (Jan 23, 2013)

I plan on using two very similar to this...

https://www.google.co.uk/search?q=p...clamp_lamp_for_par30_and_par38_lights;799;596

Reef guys seem to use them alot its just not seen as much with fresh water tanks?


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## Roshan8768 (Mar 18, 2009)

If the spectrum is good it should be plenty of light... if you go with two then you will really need to watch the photoperiod. I've seen them all the time on reef tanks and they work fine so it'll work for a planted tank


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## Roshan8768 (Mar 18, 2009)

If you pay a little more and get a brand name one, the LEDS will be higher quality, the spectrum will probably be better, and you will be able to get by with 1 light on a 15" x 15"


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## Higher Thinking (Mar 16, 2011)

Par 38 bulbs have nothing to do with the kind of par as we understand it. It is short for parabolic aluminized reflector. The 38 is a reference to the size of diameter it has. It means the diameter is 38*1/8". So your bulb will have a diameter of 4.75". It's a stupid measurement, but that's how they do it. Likewise, a par 32 bulb would be 4" wide. And to be honest, these need to be suspended EXTREMELY high if you don't want algae out of control. I set up a planted tank with one of these a few weeks ago. I hooked it up and tested the par with an actual par meter. Inches under the bulb, par is at around 1100. WAYYYY too much light. I am currently using one of these suspended over a ten gallon (why, I don't know, why not?) In order to get 50 par on the substrate, I have it suspended 30" above the tank, with another 8" to the substrate. That includes going through a dirty glass cover. So the short of it is they are potentially troublesome.


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## Roshan8768 (Mar 18, 2009)

For example

http://coralcompulsion.com/led/PAR-BULBS/led-21w-REF-GRO


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## Higher Thinking (Mar 16, 2011)

chrispowell said:


> I plan on using two very similar to this...
> 
> 
> Reef guys seem to use them alot its just not seen as much with fresh water tanks?


Reef tanks use par in the hundreds so these bulbs can work. But like I mentioned above, these are just too strong for a freshwater system unless they are super elevated.


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## Roshan8768 (Mar 18, 2009)

Higher Thinking said:


> Par 38 bulbs have nothing to do with the kind of par as we understand it. It is short for parabolic aluminized reflector. The 38 is a reference to the size of diameter it has. It means the diameter is 38*1/8". So your bulb will have a diameter of 4.75". It's a stupid measurement, but that's how they do it. Likewise, a par 32 bulb would be 4" wide. And to be honest, these need to be suspended EXTREMELY high if you don't want algae out of control. I set up a planted tank with one of these a few weeks ago. I hooked it up and tested the par with an actual par meter. Inches under the bulb, par is at around 1100. WAYYYY too much light. I am currently using one of these suspended over a ten gallon (why, I don't know, why not?) In order to get 50 par on the substrate, I have it suspended 30" above the tank, with another 8" to the substrate. That includes going through a dirty glass cover. So the short of it is they are potentially troublesome.


Agreed. You will need to suspend the lighting at least 20-24 inches above the tank. At this height, a tank clamp is not an option, so you will have to buy a pendant for the bulb or diy a hanger out of conduit or shelf. They pump out crazy amounts of light which is why they are so popular in the saltwater hobby.


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## Roshan8768 (Mar 18, 2009)

Since he has a cube shaped footprint it is an ideal light if he can deal with the light spill over and the high mounting. Obviously CO2 will be a must and you will have to watch the photoperiod


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## gus6464 (Dec 19, 2011)

http://www.plantedtank.net/forums/showpost.php?p=3985433&postcount=222


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## n5750547 (Jan 15, 2014)

Where would one buy the socket for one of these? Or would you have to tear up a lamp of some description?

Tapatalk Note 3


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## Roshan8768 (Mar 18, 2009)

n5750547 said:


> Where would one buy the socket for one of these? Or would you have to tear up a lamp of some description?
> 
> Tapatalk Note 3


They screw into your standard socket. You can buy one at Home Depot or Lowes. Any hardware store should have it really. You can also use a light fixture as long as there is sufficient space between the bulb and the shade so that it doesn't overheat


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## chrispowell (Jan 23, 2013)

Thanks everyone for the help so far - need alot more though...

I plan to modify this lamp - remove the base and fix it behind the tank.. 

http://www.ikea.com/gb/en/catalog/products/60110901/

The maximum height I can mount it would be 47" above the substrate - Do you guys think this will work or see any issues???

Many Thanks


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## Bettatail (Feb 12, 2009)

Higher Thinking said:


> Par 38 bulbs have nothing to do with the kind of par as we understand it. It is short for parabolic aluminized reflector. The 38 is a reference to the size of diameter it has. It means the diameter is 38*1/8". So your bulb will have a diameter of 4.75". It's a stupid measurement, but that's how they do it. Likewise, a par 32 bulb would be 4" wide. And to be honest, these need to be suspended EXTREMELY high if you don't want algae out of control. I set up a planted tank with one of these a few weeks ago. I hooked it up and tested the par with an actual par meter. Inches under the bulb, par is at around 1100. WAYYYY too much light. I am currently using one of these suspended over a ten gallon (why, I don't know, why not?) In order to get 50 par on the substrate, I have it suspended 30" above the tank, with another 8" to the substrate. That includes going through a dirty glass cover. So the short of it is they are potentially troublesome.


+1
The power of the LED bulb is its efficiency, and the LED bulb concentrate the light energy in a small area according to beam angle.
It is economy to use light fixture with LED bulb, there will be more and more people realize it.
Because only need one lamp and a bulb for small tank, or a track light fixture and several LED bulbs, for large size tank, $50-$100 can make it possible.

The most difficult part is to find out the PAR reading without the right equipment.

BTW, I placed order for two 15 watts LED bulbs yesterday(plan to use one bulb), all Par20, 45 degrees beam angle. after I read your post, I start worry that it is going to be too much PAR, because I can't move the light fixture further away from the tank(it is a sump, water is about 18"), anyway, Two bulbs only cost me $8 shipped, I will find out the PAR and if indeed too much, I will buy lower power consumption Par20 bulbs.


To OP,
People choose Par38 LED bulb because large diameter, more LEDs can be fitted and the wattage can be as high as 25 watts.
But you don't need that much power, all 25 watts power effectively transfer to light energy and concentrate into 30 or 45 degree beam angle, too much for the plants.
Get a Par20 or Par28 bulb, just so many to choose from, 3 watts to 15 watts, 45 degrees beam angle($5 a piece on ebay), as long as it is E27 base, it can fit most of the light fixture/lamp(E27 base), another popular base is GU10, some track light fixture use GU10 base.


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## Method (Feb 13, 2011)

I have three PAR38 bulbs over my 75 gallon paludarium. I use ones with 120 degree optics, which spreads the light out a good bit. My tank has been set up for a month, all my plants are growing, and I've had zero algae. Love these bulbs.


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## micheljq (Oct 24, 2012)

chrispowell said:


> I plan to modify this lamp - remove the base and fix it behind the tank..
> 
> 
> Many Thanks


If you do this your plants will turn towards the rear of the tank.

Michel.


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## chrispowell (Jan 23, 2013)

So people opionions are that it will work but my bulb suggestion and fixture will not? 

Im struggling to find a PAR20 or PAR28 bulb? 

IF I used the bulb I linked to in the original post can anyone give me a rough idea of what height I will need to mount it???


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## chrispowell (Jan 23, 2013)

I need to work out a workable height for the light to be suspended so as a cheap solution I think one of these would work...

Kingavon BB-DL200 E27 Desk Lamp - Black: Amazon.co.uk: DIY & Tools

I could fix it to the wall and have it come out horizontally over the tank pointing down... 

Will this work with the original bulb?


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## Method (Feb 13, 2011)

Check my sig for a cheap way to hang these lights.


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## chrispowell (Jan 23, 2013)

Method said:


> Check my sig for a cheap way to hang these lights.


Thanks for that - really helpful. How do you find the bulbs work for you???

Can you link me to the bulbs you are using?


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## Method (Feb 13, 2011)

I haven't had any problems. They're about 21 inches from the substrate. They grow both the emersed and submerged plants really well and I don't have any algae.


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## chrispowell (Jan 23, 2013)

I have found these as a possible alternative.. 

http://www.swelluk.com/aquarium/fis...a-stretch-freshwater-led-lighting-561962.html

The 50cm Freshwater unit utilises a mix of 1.5W at 10,000K, 8,000K, RGB and 0.24w RGB LEDs.

Would this be good for most plants or is this not enough lighting??

At 40cm above my substrate this unit will give me 15par.


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