How many watts?

Question

I have a 75 gallon tank and am getting T5's how mant watts do i need to be able to keep clams and any type of corals or would it be better to get metal halides, and if halides are better how many watts and lights. For mh's could i get 1 400 watt and hang it in the middle of my hood or do i need like 2 150's?

Answer 1

For clams, I would recommend going with the MHs, although some species will be okay with T-5 lighting as long as your tank isn't more than 14" deep. The MHs are also better if you plan to keep hard corals. The major difference between the two systems is how far the light will penetrate into the water, so keep this in mind since if you plan to keep clams, they will most likely be toward the bottom of the tank. Another possible consideration for you is water temperature, and the MHs will produce more heat. If the room you plan to keep the tank is very warm, you may need to invest in a chiller if the lights heat the water too much. Temperatures above 85oF on a consistent basis may cause the clam and corals to expel their symbiotic photosynthetic algae.

I would suggest at least 250W for your tank for clams and corals. Another possibilty you haven't considered in your question is to use a combination system. These use two different types of lighting so you can change intensity over the course of the day. This will give you brighter lighting, since one component is a HQI (double-ended) metal halide of a lower wattage combined with compact fluorescents: http://www.thatpetplace.com/pet/group/10952/product.web or T5s: http://www.thatpetplace.com/pet/group/23718/product.web
more choices: http://www.thatpetplace.com/pet/cat/info/22943/category.web

Really, this boils down to something that you need to base on the lighting needs of the type of clams and corals you want to keep.

Answer 2

Your thinking about the absolute minmum for normal corals. If you want clams you should have about 10 watts per gallon. So the math is 75 x 10 = 750 watts. Metal halides provide significantly more light (which also looks very natural), but produce ALOT of heat. If you get metal halides i highly recommend buying a chiller to go with it. If i were you though i would try and get a power compact system. Worked for me.

Answer 3

5 WATTS PER GALLON