Both are fine choice
However, there are differences which you will need to choose between the two.
MH,
PROS:
~Well approved technology that most people are still using up to this stage.
~Lower initial cost
~Mimic sunlight spectrum
CONS:
~Higher electric bill ( low efficiency)
~A lot higher heat compare to any other light source
~Less to no control over the fixtures
~Higher operation cost ( electric bill+light bulb change every 8 to 10 months)
LED
PROS:
~Really low heat compare to all other options (higher efficiency)
~Energy saving
~full control over the fixture( sunrise,sunset,cloudy,lighting ) some fixtures even able to connect to computer to monitor the spectrum
~Long lasting no bulb change
CONS:
~Higher initial cost (even the cost has been dropping crazy)
~A newer technology compare to
MH
~ Spectrum are depend on combination of the
LED and brand of the
LED chip (CREE,Bridgelux)
~Sometimes the
LED could mean a lot of reading and even DIYing
~No light bulb change ( Yes this is pros and cons, as
LED fixtures doesn't require bulb change, but once the
LED reach its life span, it will simply go dead and you will either replace the dead
LED chip or replace the whole fixtures. Most of the people will choose the 2nd option because it is much easier)
So Overall ask yourself few questions.
1) Is my area hot enough already so adding another heat source would kill my fish/coral?
If yes, you will need to include the cost of chiller in your initial cost. As using
MH without chiller in most North America Summer can end up a disaster.
2)Am I able to afford a bit more ( about $100 per fixtures) as initial cost ?
3)Do I want to have cool control over the fixture so I can mimic the nature?
4)Am I willing to spend time to learn about new technology?
If those answers are yes then
LED is your choice, if no then
MH should be your choice.
I had lost so much money over the heat issue and you can tell I am not a big fan of
MH, but many other will tell you otherwise.
IF you do have questions regarding
LED, I would gladly help.