What is the min. MH light needed for 4x2x2.5H tank

yongwil · May 26, 2005

Hi Bro

Intend to get a 4x2x2.5H tanks for SPS, what is yr suggestion for the light needed. quite

confuse on the 10k 20K different? Pls enlighten me!

thks

Eric · May 27, 2005

Hi Bro

Intend to get a 4x2x2.5H tanks for SPS, what is yr suggestion for the light needed. quite

confuse on the 10k 20K different? Pls enlighten me!

thks

If ur height is 2.5ft & you planning to keep a sps tank, I think you will need 2 x 400W MH, then you dont have to worry abt placement. 2 x 250W might not have enough PAR to reach the bottom, however you can choose to place less light demanding sps like monti cap or digitata at the btm............then you will have no issue liao.

I luv my 10K supplement with actinic T5. Have tried 2 x 250W 20K, luv the view but couldnt get enough PAR for the SPS at mid of tank (2.5ft height) plus I find the growth very slow, now using XM 10K.........very happy with it.............will try out the 14K bulb if got chance, then can save some electricity on the actinic T5 liao.

Eric

iantoh · May 27, 2005

hi yongwil, heres two fantastic articles on lightings that i came upon in my research during my last upgrade and they debunk lots of indicators and clarify the most important aspects to marine reef lighting. for example, you mention 10000k and 20000k. these kelvin ratings only demonstrate the colour temperatures of the light bulbs and do not specify totally the kind of wavelength spectrums they emit nor the intensity of the light produced. natural sunlight is actually 5000k with a CRI of 100. in typical reefs from which our corals originate, the lights received will be about 10000k as the red, yellow, and orange (shorter wavelengths) will have been refracted or diffused out as the light travels pass the first few meters from the surface. hence the light in reef areas are usually more blueish in colour. for increasingly deeper reefs, 12000, 14000, and 20000kelvin. for a typical mixed reef, my recommendation will be either one 6500k bulb and one 10000k bulb plus one actinic bulb of 420 to 470 nm in wavelength spectrum; or one 10000k bulb, one 20000k bulb, and one actinic.

metal halides are a good choice for sps as their lumens rating, that is, the penetrative strength of the light given off is super high- above 5000. HOT5s are typically about 3000 lumens. think you might have to think more about the wattage of your MHs than the colour temp of the bulbs as thats pretty straight forward- 10000k being the middle choice. perhaps a four feet MH fixture with two 150 or 250watt MH 10000k bulbs, together with perhaps one 6500k and one 20000k HO T5 bulb, plus actinic PL bulbs? i'm giving you the best possible combinations that will ensure the fulfillment of most coral's needs, but youll have to decide based upon your budget and also on other's comments and recommendations ya as this is from what ive learned and experienced and other's might know more or have different experiences. i think two 250watt 10000k MH bulbs, honestly, will suffice to keep sps in your tank. the rest are just beneficial safe guard extras. plus the actinics for aesthetic looks.

well.. hope that helps. try reading the articles. they explain the factors better than i have.

cheers,

ian

scarab · May 28, 2005

I'm not much into reseraching articles and stuff but here's my light configuration. Hopefully it can help you as it comes from my personal experience.

My tank size 3.5ft x 2 ft x 2 ft

MH 3 x 250W DE 10000K BLV (Photoperiod 8 hours)

T5 8 x 54W (6 Aqualight Coralblue and 2 Aquaz actinics) (Photoperiod 14 hours)

Height of light from water surface is 7 inches

I'm keeping most of my acros and light loving SPS the top two third of my tank. Monti caps and some LPS and Ricordeas line the lower third.

IME 250 W DE bulbs have no problems reaching 2 to 2.5 feet deep if you know what corals to place. So knowing different SPS light requirement will be helpful. Unless you want to place Acropora hyacinthus tables (these are super light loving corals) on the sandbed, 250W 10000K DE will be good enough. Monti caps are lovely corals and they will do really well on the sandbed. I even find some monti caps do well when they are partly shaded.