40 breeder/250MH Question

[returnofsid]

I'm revamping my 40 breeder frag tank, which has been lit with a 6 bulb Tek5 fixture. I'll be adding a SWC Mini HOT skimmer and changing lighting. The new lighting will consist of a Hamilton Bali Sun, 250MH pendant, with a 14K SE bulb in it. My question is, how high above the water, should this fixture be suspended?

This frag tank will be for growing out SPS corals AND LPS (Acans and Chalices, mainly) AND Zoanthids. I plan to keep most of the LPS on the bottom of the tank, possibly under a frag rack, to provide some shade. SPS will be mostly Acropora.

 

[dmorazan]

mine is about 8 inch above the water line and have a 175w so yours should be about 12 inch all depends on how deep is your tank and if the frags are doing ok.

 

[returnofsid]

I currently have it sitting about 10" from the water, with the ability to lower it about another 2", if needed, or raise it as much as I want. Right now, I'm liking where it is.

 

[butts182]

I posted this on my local forum yesterday...I'm sure it will help:

These are the PAR readings. I have a 40 breeder with a new Hamilton Deluxe 36" MH/T5 combo light. The light has 1 250 watt mogul MH and 2 36" 39 watt T5s. The Hamilton fixture came with a magnetic ballast, which I did not upgrade. I ordered the fixture with the 14k Hamilton bulb. The T5s provided were Hamilton actinic bulbs. I replaced the T5 bulbs with 6 month old ATI blue plus bulbs. Then I tested the PAR (it's the number not in parenthesis). Recently, I upgraded the ballast to a adjustable Lumatek E-ballast and a 250 watt Radium bulb. I also added some used T5 reflectors up inside the fixture to help reflect the T5 light downward. The new PAR numbers are shown in parenthesis! (MH bulb is 12-13 inches above tank).

Just below surface...Back.....X.............120(150).....48(60)
........................................95(115).....215(260).....77(90)
............................Front.....59(80).......185(220).....70(80)

Mid-depth...............Back.....X.............100(120).....58(70)
.......................................120(150)....130(150).....95(105)
............................Front....135(180)....200(220).....160(170)

Bottom..................Back.......X................X............60(70)
.......................................115(130)....90(120).......85(105)
............................Front....115(120)....150(155).....120(130)

Well, I got an increase of roughly 10%-20% in the PAR with my modifications/upgrades over the stock fixture and I have a 20k bulb instead of a 14k bulb, which makes me happy because I like it blue. I hope others who use the PAR meter post their PAR readings too.

 

[Troylee]

my 250 is about 16" off the water but it's a new setup so im kind of in the same boat.... im trying to figure out if im to far away or not... i guess time will tell my tank is 18' tall and i run a 250w hqi phoneix 14k with four t5's and soon 36 cree 3w leds on top of that haha...:xd:

 

[NaplesAquatics]

You can always shade some/all of the tank to acclimate corals or provide lighting differences beyond the simple up/down in the water column. Nylon window screen works well for this with a simple frame.

Jeff