760 watts on a 75g?

[Sregnar35]

Hello, I recently upgraded my 75 gallon with better lights. I'm going from 260w power compacts to 760w power compacts and halides. Anyone have experience with this much light in a tank this size? I've already begun moving my coral lower in the tank, and I plan to short cycle the new lights when they arrive. Also, what sort of temperature issue will I have? Currently there are 4x65w pc's, I'll basically be adding 2x250w halides to that. The lights are in a pre-assembled strip with legs, so it will probably be about 4 inches from the surface of the water. My water is 77.5 and 76.5 at night.

 

[Grins]

I have (2) 250 watts over my 55g. I have fans, 3 seasons out of the year, that are set to turn on when the MHs come on. I do not use a glass top, and my canopy is open at the top and the back for the most part. On extremely hot days I compensate by using frozen bottles of water. However that is no more than a week for me. If it was more than that I'd consider a chiller.

I don't feel you'll have too much light for your 75, but you will want to account for evaporation running an open top with hotter lights. I use an auto top off system.

Oh, mine are kept 9" off the top of the water.

 

[Sregnar35]

Thanks, I've always run with an open top (wow that sounds bad) and I'm already used to the evaporation. I live in upstate NY so we never get too too hot up here, my house is usually below 75 degrees even on the really hot days. I guess my concern now is the distance between the tank and the lights, and how my leather will do. The leather I have is huge and even if I put it on the substrate it will be only 3 or 4 inches from the water surface.

 

[Grins]

Hmm,, not positive but Clown-lover and FSN77 might both have toadstools under MHs, you might ask them.

 

[Amphiprion]

That is a difficult situation. You will certainly want to acclimate it. However, the leathers can do just fine under halides so long as they are accustomed to it. I suggest maybe raising the fixture well above its intended position and maybe a shorter photoperiod as well.

 

[Sregnar35]

I'll have to devise a way to elevate the new lights. My tank is in my wall, I actually had to cut some sheetrock back just to accomdate the new lights. Hopefully I can put some blocks under the legs of the new lights to jack them up a bit.

 

[Amphiprion]

Well, if it is more difficult to raise them, try the "screen" method. Basically, you get a series of screens and shade out a decent portion of the light and, over weeks, you gradually remove those layers. Seems to work fairly well, if that is a better option for you.

 

[Sregnar35]

What sort of screens would I use?

 

[Amphiprion]

Fiberglass window screens and pin them between a frame of pvc or wood that can be easily removed for alteration, etc. (or make multiple smaller frames, whichever is easier).

 

[Sregnar35]

Great, I'll be going to home depot tomorrow I guess!