MH vs PC on big tanks

[Guest]

Hello all,

MTS seams to be setting in. After building/running a successful 40g planted tank. I'm really wanting to step up to a 75-125g planted tank.
I'm sure I can find another use for the 40g

I'm shooting for about 2.5-3wpg, with pres CO2. Can anyone offer some advice on pro's/con's of MH vs PC. Such as cost of set up, power consumption in the long run, heat generated etc....

I'm very satisfied with the AH Supply lighting I'm currently running on the 40g. Thier refectors are excellent. Seeing how the bigger the planted tank. The more it cost to build. I'm wondering if MH might be a little more cost effective.

Any ideas out there? Thanks

Also, I plan on building a custom canopy, so heat dispersion would be factored into the build with either lighting.

 

[djlen3]

I have not used MH lighting, but from what I gather, realistically they should be suspended above the tank quite a bit because of the heat generated by them.
Seems to me that by doing that, one would lose a lot of light off to the sides, and it doesn't seem like a very efficient option when compared to CF.
Some people swear by them, so it will be interesting to hear other opinios on this subject.

Len

 

[Guest]

Very good point djlen. That is a big concern of mine. Most of the MH set ups I have seen, the light fixtures are suspended from the ceiling. Leaving a gap for heat to vent between the tank and lightinging. Thats what bothers me. Seeing how this tank will be in the living area. I really don't want a bunch of ropes or chains suspended from the ceiling to support a MH fixture. Not to mention maint. and water changes with such a set up.

It appears you could build a nicer, easier to maint. canopy with PC's. If one put some planning into the set up with balast placement a coupe of fans and vents. It would look much better in a living area.

If the set up were in a basement, out building, garage etc, were estetics were'nt as important. I could see were MH might be more benificial.

 

[Guest]

Also note that the MH bulbs do need to be replaced at a minimum of every 24 months and more realistically at around 18 month. Figure that into your total cost of ownership and you will see that MH gets much more expensive real quick.

 

[fishfreek]

On the PC setups I use I find I have to replace the bulbs every 9 months or so. If I run beyond 9 months the light output drops off significantly and the color shift on the bulbs is very noticable. IMO the cost of ownership is lower with MH than PC.

ANother alternitive that you havent mentioned is VHO. Now that I have a tank with VHO and a tank with PC I can tell you I think I like the VHO light better. The bulbs are going on 9 months now and I havent noticed the VHO drop off in intensity that I do notice with the PC's at that age.

VHO puts off less heat than the PC bulbs and significantly less heat than the MH.

There are many ways of doing MH lighting. The pendants are just one of them. Another is to put them in an enclosed canopy and have them 10" or so above the water surface. You will want fans in the canopy of course to vent the air.

 

[Guest]

I have PC bulbs that are into their third year of operation and have not noticed any noticeable decline in the output at all. There is some in the first couple hundred hours but after that not much at all.

Tom Barr runs bulbs till they die. And there are maybe at most a handful of people alive today that know more about planted tanks than Tom.

As I have stated before the whole idea of replacing fluorescent bulbs started back when the first people started keeping reef tanks.

 

[Guest]

Some very good points. PC's seam to be more practical and cost effective. Any more opinions out there?

 

[BrianNY]

Hey Mojo..........I've got 6 X 55s on my 125g. It doesn't throw as much heat as you might think, and I don't need to use a fan. Important: When you build the canopy, allow an extra inch in height and use the spacers provided to keep the canopy from contact with the reflectors. This air gap is all you need to dissipate the heat.

 

[Momotaro]

I'd go with the PCs also Mojo.

PCs are much easier to set up, no need for a big install, just sit them atop your aquarium. PCs are also cheaper to run considering Rex's input on the need to change the bulbs frequently. You can run your PC bulbs until they die, so you will certainly change them less than the MH.

Mike

 

[djlen3]

I retro-fitted 2X55s into the old plastic hoods on one of my 55gals. with no fans and no problems. The ballast is attached to the back of the fixture.
I agree with Rex on longevity. I've got 2 years on mine and no noticeable drop off in color or light output.
For nice retro-fits at reasonable prices: www.ahsupply.com

Len

 

[chasgood]

I just ordered a 55watt PC for my 37gal. They seem like the best choice for me.
Does anyone have any percent figures on how much more efficent they are compared to regular T12 or T8 fluorescents?

 

[Guest]

Depends on the reflectors.

 

[betowess]

If they are AH Supply's, about 60% more efficient because of the reflector design and where the bulb is mounted. They are the best in the business IMO.

 

[Guest]

Chasgood,

Make sure you stick to low light plants with that 1.5 WPG set up . I agree AHS is a great bargain.

 

[chasgood]

I plan on staying with low to moderate light plants. The 55watt PC will be about a 50% increase in light so the plants I have should do better.