Was I wrong for downsizing my MH's?

[johnnstacy]

I'm beginning to think I was. I started my 180g (standard dimensions) with three 400W DE PFO's with 20K lamps. I felt like it was to much light so I changed them out for three 250W DE PFO's. So why do I think I blew it? Well, I recently moved and during the transition, I had all of my rock and corals in a big 150g rubbermaid bin. I set up a makeshift lighting system but the corals were much closer to the light then normal. As it turns out some of my corals got some intense color! Exactly the opposite of what I thought would happen. I had noticed some of my corals looked like they were getting bleached. Now I am beginning to wonder if I had them to low in the tank all along. The heighth from the bottom of the tank (no sand) to the top of the water is 21". Then another 8" to the bottom of the MH fixtures. The corals mounted the highest in my tank are about 8-10" from the water surface so then add another 8" to the MH and you have a total of about 18" at best. I have many lower then that. Calculated out, many are from 18-25" from the MH
Can anyone shed some light (no pun intended) on this issue? Should I have stayed with the 400W DE's or are the 250W DE's okay. By the way, when I changed to 250W DE's I changed to bulbs to a 10k lamp.

 

[johnnstacy]

Oh and sorry. This could have probably gone in the equipment forum but my tank is almost all sps also.

 

[Horace]

IMO your setup with 400w 20k was ideal. The 20k bulbs need to be driven at 400w to get any significant amount of PAR. The PAR on the 250w version of the 20ks is typically abysmal. I would never run a SPS tank on only 250w 20k...I just dont think its a sufficient amount of light and I think growth would suffer greatly. Color might be pretty nice though...not sure.

One of the best tanks I have ever layed my eyes on is a 240g with 4x400w XM 20k.

Given that you are running 10k...you should be ok PAR wise but I doubt you will see the colors you would with the 400w 20k

 

[johnnstacy]

You think you get more par with 400W 20k's then you do with 250W 10k's? I wouldn't have thought so.

 

[Horace]

<a href=showthread.php?s=&postid=7887053#post7887053 target=_blank>Originally posted</a> by johnnstacy
You think you get more par with 400W 20k's then you do with 250W 10k's? I wouldn't have thought so.

Pending your bulb selection, absolutely the 400w 20k may put out more PAR. Now will the 400w 20k beat out a 250w 10k on an HQI ballast, nope. It all depends on the ballast bulb combo, so you have to look at Sanjays numbers to tell. The XMs when compared put out pretty similar numbers...the 10k puts out like 137 and the 20k 128, assuming both are on magnetics. There are plenty of 10ks that dont put out the PAR of the XM 10k though so like I said, its all about the bulb/ballast combo.

 

[JB NY]

If you are going to go with XM10K, 250watt DE are more than enough. I ran 250watt SE and never even though about upgrading to DE or 400 watters.

 

[marinelife]

where can we see Sanjays numbers

 

[King-Kong]

http://www.reeflightinginfo.arvixe.com/

 

[marinelife]

why thank you, I had it once before but lost it

 

[nwrogers]

I love my 400w 20k bulbs. I was worried at first that it would be too much but as it turns out the color is great. I have never run 10k bulbs so I have anything to compare it to but I really like what I have now and don't plan on changing anytime soon.

 

[jay24k]

I didn't think XM made 10K DE's. I would of just kept the 400 unless your electric bill was ripping into you.

 

[johnnstacy]

What about distance from light to corals? Do the measurements I give in the opening post sound accurate for most tanks?

 

[jay24k]

I have mine about 6" so 8 is fine. A 250 watt DE depending on the bulb will probably overpower that 400 watt 20k. What I would personally do is put window screen over your tank and remove a sheet each week for 1 month. Because the light is SO strong, bleaching is happening.