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150w MH vs 130w PC


NonSequitur

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I was pondering last night (couldn't sleep, too excited about the new tank), and ended up wondering about how the light output of a 150w MH compares to a pair of 65w PC lamps. I'm considering swapping out the PC's on one side of the new tank for the 150w MH I have, but don't want to do it if I won't be gaining much.

Alternately, I might be able to use the PCs along with the MH to get even more light on that side of the tank. Right now I only have one MH fixture, so I was thinking of putting it on one side of the tank, keeping the other side PC to accomodate lower light corals.

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The main thing you need to remember is that you really shouldn't add Actinics to your light load when figuring out if you have enough light for a specific animal. Most PCs are 50/50 actinics so (assuming that is the case) you really have 65W, say bump it up to 85 or 90 for the actinics. I've also noticed that the MH seems to have better "penetration" than my old PCs did. Allowing me to grow corals in the sandbed or low in the rocks.

From personal experience I went from a 96W 50/50 coralife PC fixture to a single 175MH pendant in a 24g Nano. I saw an immediate change in the growth rate of my tank for the better. It was most obvious in the couple of SPS I had at the time. They went from looking like they were barely living to really looking like they were thriving within a week. My Zoas went from slow growers to the point where I am going to be offering some frags up of them in the next couple of months. I also notices a very fast "colouring up" of the corals. From muddied colors to bright blues and reds and yellows. The SPS 14K light also helped a lot in the color department when I switched to that over the hamilton 10k light but I think that is just because of a better visible color spectrum bringing out the colors that were already developed from the original switch to a MH.

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You will see a world of difference. That 20w may not seem like much, but look at the reflectors on each lamp. I would bet the PC unit will just have a simple flat reflector, maybe white. Also, the design of the lamp itself will limit how much light will be directed down.

Comparing MH to PC is apples to lima beans. No contest.

I'd just center the 150 for now and pick up another when you can. Use ledges for creating shaded areas for the low light lovers.

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Thanks for the replies. I had a feeling that was the answer, but looking purely at the numbers I couldn't figure out how it could work out. I had forgotten about not counting the actinics, since the lamps are indeed 50/50s, the reflectors, etc. I'm going to work on adding the MH, and picking up a second one (or a pair of 250s) when I can. I've seen so many gorgeous clams recently that I'd really like to try keeping one, which I'm not about to try under PC alone.

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