Thinking of downgrading my lighting. Thoughts?

[seminolecpa]

Currently I am running 2 250W 20K XM Bulbs on a standard magnetic ballast.in my 58g. It seems however that anything near the top or high middle of my tank doesn't care much for the lighting and does better toward the bottom or low middle of the tank.

At first I though it may have just been the coral itself but I have noticed this with several of my corals now.

Everything is still growing well but I don't really see a difference in growth rate from the top to the bottom (only a color difference).

I am considering downgrading to a 175 W ballast and bulbs as I am due for new bulbs anyway.

Other important info. I run my halides for 6 1/2 hrs a day and they are about 8" from the water surface.

Any thoughts?

 

[Cody Ray]

That seems odd. You might try only replacing one with a lower watt system and then placing corals higher in the aquarium. If they do the same thing than I would say its flow. If they do better than replace the other. I bet it won't be hard to find someone willing to trade you for a higher watt system

 

[undertai]

Try change the mh lighting period. I run 175'3 over a 55 for 8 hours no problem; try setting for 6 ro 4 hours and see what happens

 

[aurora]

How about raising your hood about 2 inches? To me, that would seem much easier than swapping out the whole light system.

 

[seminolecpa]

Raising the hood isn't an option as it is a custom canopy so the distance is pretty well fixed.

I have thought about shortening the photo period even more but when you get down to 4 hours with lights on how does it even give you a chance to enjoy your tank.

Wouldn't it make more send to keep the same or lenghten the photoperiod with less intense lighting?

My other problem is that if I am having what I perceive to be a problem with 20K bulbs what happens when I want to go to a less blue bulb?

 

[JR719]

I'm having a little of the same problem. Although, as ChinChek787 said, mine if flow. I have more flow near the bottom than the top. Does'nt really bother me though, I have a couple of clams high in the tank and a couple of corals seem to like it. My pocillapora and 1 montipora like it high. Other monti's don't care for it. I'm running 250W 10K XM's.
I would check the flow, with the Tunze and your maxi's, you may have too much towards the top. And if it comes down to it, would get 175's and keep the photo period the same.

 

[JB NY]

wow that's pretty starnge. The XM20K is a pretty dim bulb to start with. I couldn't get good coloration with that bulb and frags in my frga tank and that's in only 7" of water, I had to go with a brighter bulb.

 

[zenzence]

I have a somewhat similar problem! I had to move my brain coral and my birds nest to the bottom of the tank. I have a 90 with 2 175 MH bulbs. The bulbs are only about 5 inches from the water so i think that has something to do with it. I am going to move my tank next week to a new house and stand. THe light will be about 8 inches from the water so I really hope this helps. Anyone else had a similar experience?

 

[kevensquint]

Without having read the whole thread, I don't see the difference from a bigger tank using 250 watt bulbs and the corals being a few inches under the surface. As opposed to your 58 and the corals being a few inches under the surface. Unless the bulbs are very close to the water, your corals should respond similarly to anyone else using 250's and having the corals near the top. I would say raise the bulbs higher. I have 3x250's on my 65- 8.5" off the top, and my 2-20k's could'nt bleach anything...way to dimm. Maybe you have another factor that those corals don't like.

 

[JB NY]

How were those corals acclimated to the MH lighting. Maybe they were just used to very low light levels before going to your tank?

 

[RichConley]

<a href=showthread.php?s=&postid=7220188#post7220188 target=_blank>Originally posted</a> by kevensquint
Without having read the whole thread, I don't see the difference from a bigger tank using 250 watt bulbs and the corals being a few inches under the surface. As opposed to your 58 and the corals being a few inches under the surface. Unless the bulbs are very close to the water, your corals should respond similarly to anyone else using 250's and having the corals near the top. I would say raise the bulbs higher. I have 3x250's on my 65- 8.5" off the top, and my 2-20k's could'nt bleach anything...way to dimm. Maybe you have another factor that those corals don't like.

Hes got 2 250s right next to each other in a 36" long tank. SO yeah, it is more than most people having 250s in a deeper tank. Theres a TON of overlap between his fixtures.

I run a single 250 on my 58. You may want to try that. (I run 10K though)

 

[Ewan]

sorry to hi-jack,

Rich, how's your light spread on your 58? I currently have a 250w aquaspacelight mini over my 29, and I'm thinking of upgrading to a 58 in the near future. I assumed I'd need 2 halides for that tank.

I guess the reflector is key in this case... Which reflector do you use?

-E.

 

[RichConley]

DE in ROIII. the only place I have any light problems is up top in the corners. It looks perfectly well distributed, but thats probably the lowest light area.(less than the areas lower than them , because of the cone shape) Montis grow fine


A lumenarc mini woudl probably be the best for this. Honestly, I bleach out some stuff near the top middle, so I think 2 250s on decent reflectors is a lot (I also run ozone, and carbon, so my water is clearer than most, which helps with penetration.)



FWIW, I love the tank size, other than the fact that I can't keep an Achilles Tang in it....

 

[kevensquint]

<a href=showthread.php?s=&postid=7220615#post7220615 target=_blank>Originally posted</a> by RichConley
Hes got 2 250s right next to each other in a 36" long tank. SO yeah, it is more than most people having 250s in a deeper tank. Theres a TON of overlap between his fixtures.

Ahhhh, you might want to try one bulb only, or a short period of 2 bulbs on and the rest of the photoperiod one bulb. However, only 1 ~20k bulb won't give you the best growth, if I was going to try only one bulb, I too would go with 10K (xm)

 

[seminolecpa]

This isn't a new problem and most of the corals have been in my tank for well over a year so I don't think it is an acclimation thing.

I pretty much ruled out the water quality thing too as like I said I have no problems in the lower part of my tank.

Flow is something I haven't totally considered but I am not sure it is the culprit either as I have few if any dead spots and any I do have are likely in the lower part of the tank vs. the higher part. I run a Tunze 6100 in the back right corner that banks off the fromt glass. The have 3 Rio 6100 powerheads placed randomly to pick up the dead space. Running a Mag 7 for my return

Again they are a good 8 inches from the water but it is a closed lid
canopy (see pic 1 in my gallery)

My though was to go with 2 175W 10K bulbs vs. 2 250W 20K bulbs. My 250 W ballast is a dual ballast.

 

[Tyrosinase]

Are your bulbs double ended? Maybe you are getting to much UV in your tank. I had a similar problem in a 35 gallon hexagonal tank where I was running a 150W 14K bulb. There was one spot in my tank where my acros would always die. Ever since I placed a piece of 1/8" acrylic between the pendant and the tank I have not lost any acros. (In case you were wondering, the pendant already had a piece of glass between the bulb and the tank.)

 

[seminolecpa]

nope SE