We currently run two 250W Galaxy ballasts with 20k Radium bulbs on the 250 gallon tank. We see marginal growth from the SPS and LPS corals with this setup. Would changing to 400W ballasts and bulbs be a significant "upgrade" for coral health and growth? What are the positives / negatives over the current setup? Thanks!

With out checking your PAR levels I think it would be hard to say if switching lights would make a difference. IMO though I think it would be a waste to switch to 400s. I would look more in to your water conditions and water flow. 400s are going to provide more light but also more heat and more electricity. Sanjay lights his monster tank with nothing but 250w bulbs and he has incredible growth.

Edit: what kind of reflectors do you have and what kind of spread? On my 180 I used three 250w bulbs. Depending on the length of the tank you may need to add another bulb (two might be spread too thin).

What are the dimensions of your tank? If you have a 6ft tank 2-250's would be okay if you don't have a tall tank. I have a 165 tall tank which is 30" tall and I need 400 watts to reach the bottom. If you have a 7-8ft tank I would think you would need 3x250's to cover the spread. IMO
400's are obviously going to cost more to run and extra heat. But if you only run them for 8hrs and keep a room temp around 72, over heating shouldnt be much of any issue. I did notice that NAS did have some used chilled available if you were really concerned about the heat.
I have 2-400's and 3-LED panels and my tank never gets above 80. Water conditions will affect growth. How often do u do water changes?

The tank is 60" x 37" (deep) x 27" (tall).

I don't think it is water conditions unless the water is 'too clean' as all parameters are right on target.

Water changes are done ever other week at 25 - 30 gallons typically.

I think you would be happy with 400's then with some good reflectors with the dimensions of your tank. Ballast will be about $150 each and then $120-$150 for reflectors.

I agree with Skippers statement, there are probably other things that would be wiser to invest in versus upgrading from 250 to 400. I use a six bulb TEK T5 fixture on my 75 and get excellent growth.

Are you supplementing (dosing or calcium reactor)? and monitoring (Ca and Alk)? what about Mg (dosing and monitoring?)

Do you feed your corals? What type of flow do you have? Those will contribute to better growth in addition to light. As Skipper stated Sanjay "lighting Guru" isn't running huge amount of light over his 500 and his tank is awesome. I run 3 400W over my 600 at home and get good growth on my sps, but I also supplement "fuel" 3 times a week and feed my fish pretty heavily. (spoiler alert....said lighting Guru is going to coming to town soon )

nebraskaaquatic wrote:Nice!

The color of the radium is your draw correct? We know it's pretty weak, par wise. Have you considered LED as an option? I wouldn't want to pay for, or deal with the heat of a 400w system at all. It's a land of diminishing returns.

I am with Daniel. The coin you'll drop into 400w setups will be pretty pricy.

jb61264 wrote:
We have a Kalk reactor that is connected to the ATO. We do testing across the board typically after every water change or if something doesn't seem right.

I run a 250w Radium/Galaxy set up on my tank and have for years. I get outstanding coral growth on all the corals in my tank. All the par info I have ever seen on Radiums shows them to be an excellent bulb for both color and PAR levels. BTW, I only run 3 Radiums over a 410 gallon 8ft long x 3ft wide x 27" tall tank. I have them each in 22" sunlight reflectors so I get outstanding coverage in my tank. Of course it helps to understand what corals like what kind of light and put them in lighting situations that work best.

Also flow can play a big part in coral growth, as well as tank parameters and feeding habits. You will not need more wattage for your setup, but you might want to try larger reflectors on this setup if you are running somthing smaller.

nebraskaaquatic wrote:
We do not feed the corals specifically. Flow comes from three Tunze 6105's and two Tunze 6095's (as well as the typical return pump).

Landshark wrote:
I forgot to mention, we utilize Lumen Bright 3 reflectors.