adjusting light intensity for acropora

[Acroporaaddict]

Running a 36" giesemann spectra with 2 250w Radiums on m80 ballasts, fixture also has 2 39w Blue+ and 2 39w Coral+. Currently the fixture is 14" above the water surface, the halides are running for 5 hours and the t5s are on for 8 hours. I want to increase my light intensity, would you recommend leaving the fixture at the same height and increasing the halide photoperiod or would you keep the photoperiod the same but lower the fixture closer to the water surface?

 

[jwshiver]

I have the 48" Spectra at around 8" above the water line. I would lower your fixture and not increase the photo period on the halides. I use to run my halides for 6 hours and the growth was crazy but the colors were washed out. I reduced the halides to 4 hours and the colors are dramatically improved. All 4 T5's are ATI Blue Plus for 12 hours. I use to run the same T5 combo that you currently have. I think my colors are improved from switching to all blue but I'm not a huge fan of the Windex blue. The Spectra is also supplemented with 2 Reef Brite blue XHO LED strips that are only on when the halides are off and 30 minutes before and after the on/off time for the LED "pop".

 

[jda]

That is a lot of light.

Lowering or more time would kinda do the same thing. If you are happy with the current light spill, then perhaps leave it where it is and up the time.

I might suggest that you turn the T5s off when the MH is on. Maybe run them for 1-2 hours before, MH for 5 or 6 and then T5s for an hour or two after. The MH alone is more than enough light, so save the bulb life and electrical costs of the T5s when it is on. I have VHOs on one of my tanks and I turn them off when the MH are on since I cannot really see them do much to overpower 3x 20k Radiums on m80.

 

[Acroporaaddict]

Do you happen to know the wattage of your radiums on m80 ballasts? One of mine is pulling 280ish and the other one is pulling over 400. I switched the outlets to see if the apex was reading incorrectly and getting the same readings on different outlets. Any ideas?

 

[Jettareefer223]

I agree with Jda and others I use to run radium 20k’s with vho’s and turned them off for the majority the time while the halides were on to save on electricity/cut down unnecessary heat radiums can grow everything beautifully alone if driven properly. I would keep the halides duration the same lower and fixture closer slowly until you’re a few inches lower 10-12 would be fine. Will help as things grow and shade other corals.

On the voltage I always ran blue wave 7’s magnetic ballast spec for radiums. Are your ballast matching? Don’t know my exact draw though, do the bulbs match color wise visually once fired up all the way? It should be noticeable if it’s that significant.

 

[jda]

All of my m80s are about 330w... some a bit more and some a bit less.

 

[Dana Riddle]

A PAR meter and PPFD measurements are the only way to go in these situations. So many variables involved. When at Wildlife, we used 400-watt Iwasaki 6500K HMs at just a few inches from the surface. Some corals did great and were wonderfully colorful, while others suffered.