I bought the Coralife 12" Dual 18W fixture for the same reason that many of you did: cost. The Dual Satellite from Current USA is a great light, but when you are trying to build a small tank, buying a fixture that can cost more than the tank setup itself kinda stings.

Anyway, I'm sure that some of you have noticed that the color produced from the stock 18W 50/50 bulbs never looks as good as the Current USA version Well, I have a way to fix that, and it's really easy. Read on...

I'm sure some of you that have been running these fixtures for a while are thinking that it is time for a bulb replacement and thinking "Crap, I have to buy the same bulbs again ". Well, if you look on most sites, you will find that the Current USA bulbs are cheaper than the Coralife ones ($6 difference at DFS), but they won't fit because they are a different pin arrangement. I have a very simple, no cost (other than the bulbs) way of getting the better bulbs in your cheaper fixture.

This is the DFS page with the bulbs on it. Stock bulbs for the Dual Satellite are the dual actinic (460/420) and the dual daylight (10000K/6500K). Change this up as you like. The dual actinic is the key though.

WARNING: Do this mod at your own risk. It's very simple, but mistakes can be made. I accept no responsibility for any damage or harm to you, your light, or your tank. Thanks

Heres the begining

Get your fixture uplugged and unmounted from the tank and get it face up on a work surface


Next, remove the splash guard by sliding it out of the end of the fixture.


Carefully remove the rubber bands holding the bulbs in place and pop the bulbs out from there clips so it looks like the above picture.


You will see a black connector on the end of the bulb. It just pulls off, but it can be a little tough after the terminals corrode a little. Just wiggle it back and forth till it comes out.


This is what you are left with. Repeat for the other bulb.


Take a look at the back of the connector and you will see two screws. These hold the connector together, and ultimately are the secret for this mod.


Remove the two screws, remove the back cover and you will see this. These are the four terminals for the bulb to connect to.


These terminals come out rather easily. Just take a tool like an allen wrench or something similar and instert it into the terminal and push it out.


Like so. Only remove one terminal, then move to the next step.


Once the terminal is removed, use shrink tube or electrical tape to fully insulate the terminal.


Now slip the terminal onto the pin for the new bulb. Here is the part you need to pay attention to. The pins on the bulbs are grouped in pairs. Same for both straight and square setups. The two pins on the left are grouped together, the two pins on the right are grouped together. I found it easiest working from one end of the original connector to the other. Think of it like this (looking at the end of the bulb, flat on the table):

Straight Pin:
1 1 2 2

Square Pin
1 2
1 2

See what I mean?


This is what you will end up with. Screw the old connector parts back together and put them away for safe keeping. You may want to use them again some day.


Insert the bulb back into the clips to keep it safe and out of the way. Move on to the next bulb.


Both bulbs finished and safe in their new home. Replace the rubber bands and the splash guard.


Genuine Current USA bulbs


Turned on, working and ready to rock. Keep in mind that the 420nm actinic will look very dim. I assure you it is working.


Put the lamp back on your tank, plug it in and enjoy your new lights. I found that the colors pop so much more because of the 420nm actinic. My bi-color frogspawn never looked better.

As an added bonus, the new bulbs run quite a bit cooler than stock. Anyone who has owned one of these knows they get so hot it almost burns. Now it's just relatively warm

I hope that this little guide will help some people out. It's nice to see that with just a little modding, you can now have more selections in bulbs. If you keep the original connector parts (and remember where you put them ) you could go back to straight pins if you wanted to.

very nice!!!

Thanks for the info. I'll be getting one of the CoraLifes soon, so this will be an interesting project when I decide to change bulbs. Question though. I get the pairing concept, but does the arrangement of the pairs matter? For example, if the straight pins are

1 2 3 4

with 1,2 paired and 3,4 paired, then the possible arrangements, keeping the pairing, are:

1 3
2 4

1 4
2 3

2 3
1 4

2 4
1 3

I think I got them all. Does it matter which of this configurations are used? Or is any combination alright as long as the pairs are kept together?

(Edit: original post did not convey my question very well)

The pairing is very important. If you were to take a bulb apart and smash the glass, you would see two small coils at the base of each tube. You have to get the correct pair of wire together to energize the coil. Get the wrong pair together and it wont fire.

Edit: got confused there. The polarity does not matter, so what you posted would work. As long as you don't pair 1 and 3 together you will be fine.

Oh, and as an added bonus, it runs cooler than the stock bulbs.

Added this comment to the original post too.

Well, after 4 days of use, everything seems to be going well. The bulbs are breaking in nicely and the inhabitants of the tank seem to be liking the new setup. I like the new setup too.

This wouldnt run 24W 50/50 Coralife 13" would it?

No. Ballast and fixture are too small. I'm sure the same principles apply to the larger fixtures though.

Ok, heres a question for you. taking into account the possible heat issues. Would I be better of running the modded CoraLife that you've shown us, or a 70w MH over my Eclipse Hex?

If you can control the heat, the 70W MH will give you more light and better results overall. The Current USA bulbs in the Coralife fixture will be the next best thing, if you have the fixture already and it's time to change the bulbs. If you don't have it and are shopping for a fixture, you might as well get the Current USA Dual Satellite.

I made this how-to to show people how to put better, cheaper bulbs into a common, inexpensive fixture.

I might just do this when the stock bulbs need replacing.

Thanks for this, this is going to really help me when I go to buy new bulbs.

Evil, you da man!

This is a great mod, I can't get all the pictures to load right now but when I can I think I'll go through with this.
I just got the coralife 12" for $36(2.5gal pico cycling) but really dislike the 2 50/50 bulbs in.
Did you ever do any par tests on the bulbs for this? And didn't think 1 actinic coralife + 1 10k or 50/50 would so much of a difference.

Plus it runs so hot with stock bulbs I'm afraid my toddler will get burned(one reason we haven't put MH over any tank)

Never did any PAR tests, but Current USA PCs are usually one of the better performers (unlike their T5s )

I think Evil will suggest the PC-R bulbs now. I think he told me that they make better light them most bulbs.

That's another option, but one that isn't availble just yet. Only a few more weeks to go hopefully. The PC-Rs will have the best performance by far.

ooooooooh nifty. I think I shall wait then. The cost is about the same compared to lfs coralife 18w's anyways compared to uvl pc-r.

Another question to shoot at you, I read on one forum that the coralife ballasts in these can run anything from 18-65watts and that he was able to switch out to different sized bulbs on the same pc ballast. But I only read one person ever saying this is possible(so I'm doubtful). You'd probably know better than anyone, could this fixture run say the next bulb size up? And(if so) at what imaginable downsides?

The ballast will accomodate a number of bulb sizes. There is only one higher waatage bulb that will still fit, and that's the Current USA 27W. Yo only have a choice of two bulbs though. The 18W PC-Rs will probably be about the same output, but lower wattage/heat.

Evil I am sure you have said in 900 other threads, but any idea on a release date? Will you be doing a full review on here?

SO evil you say the Current bulbs are better then the corallife.

My story has
420/460 dual Atinic bulb
&
Daylight bulb.


Will it work out? Im keeping softies.