View Full Version : New (to me) MH help

07/07/2010, 10:15 AM
I just got a used MH/VHO light for my 50 gal tank. I think it is 2 175W bulbs with 2 VHO bulbs (one 50/50 and one actinic). Not sure the brand but I believe it has Ice cap ballasts. It is replacing single t12 strip light. How high should I hang the new light? How long should each set of bulbs run?

07/07/2010, 11:12 AM
How high to hang the fixture is really up to you. It will be decided by how much heat your light adds to your tank, how much light spread you want/need, and lastly how much light spill you can handle. But, anywhere from 4"-12" will work (( and even lower/higher if needed )).

As for how long, that will be up to you. However, for me, I run my supplemental lights for 11 hours and my MH for 6.

What do you have in the tank now? If you have any corals/inverts you are going to have to acclimate them to the new lights. I would suggest putting some window screening b/t the tanks and the lights (( can support it with egg crate )). I have always used 3 layers and remove a layer every 5-7 days.

07/07/2010, 11:16 AM
Usually 175's don't have a glass shield, I would hang it at least 6" (at least) to avoid splashing of water onto the bulb.
Set it up higher, then lower it depending on how your corals react. try approx. 10" up first, see how they like it.
I agree with Todd about the light schedule.

07/07/2010, 11:18 AM
Good point about the splashing -- forgot about that since I have DE fixtures (( with the needed shield )) and a full SE fixture with a acrylic shield.

07/07/2010, 11:26 AM
thats allot of light for 50g tank lol, to much IMHO, I run that lighting on my 100g and can grow anything

height is going to really depend on your canopy and or ventalation as 1 150w MH in a open space flat cooks my 50g sump.

put those lights at 12" above the water with a canopy and you will still need a chiller to keep water temps down.

07/07/2010, 11:28 AM
Don't know for sure if a chiller is going to be needed.

Over my 58 I have 2*250 MH + 2*96 PC and clip on fans keep my temps in check.
My 75 has 2*250 MH + 4*54 T5, and again clip on fans keep the temps in check.

07/08/2010, 02:19 PM
Thanks guys. It has two fans for the MH so that shouldn't be an issue. i just needed a ballpark to start with. I will start with a short schedule for the MH and see how it goes from there. I'm thinking I will start with an hour and work from there. Add 15-30 minutes per week? 4-6 hours for the VHO's?