melev

Last year, I posted about the upgrade from single ended metal halides to TwinArc bulbs. I used the same reflectors and ballasts, but could now have 20,000K lighting for a few hours and 10,000K lighting for a few hours, daily. The best of both worlds, right? http://www.reefaddicts.com/entry.php...l-halide-bulbs

10 months later, I knew it was getting close to the time I needed to get new bulbs, and I was really debating what to go with: upgrade to all 400w bulbs and ballasts, or downgrade the middle to 250w to match the outer bulbs and ballasts. Part of making that decision was based on how the corals are doing, and partly on the PAR measurements I'd taken. When you look at the staghorn coral that is essentially under the 400w bulb, it's bursting with growth, yet the right side has less growth because it's in a semi-shaded spot between pendants, and the light it gets is from a 250w bulb. The LPS on the Bommie section (right end of the reef) seem healthy and full, but haven't really attempted to grow upwards much at all, so it makes me think more light would do them good. The entire backside of the reef gets less light than the front because of the orientation of the pendants themselves, specifically in relation to the sockets that each bulb screws into. Turning those pendants could shift where the light shines, and I may try that change as well with some more extensive measurements.

So here are some pictures of the conversion over the weekend. The first part was taking down the 250w bulb, socket and matching ballast.

The new ballast is from Reefbrite, designed for their TwinArc bulbs. It's a 400w ballast. The Icecap ballast it is replacing is over 10 years old.

The 250w bulb looks pretty much the same as the 400w bulb. The arc appears be a little smaller internally. The new bulb is screwed into the socket in this picture.

The end of the cord from the bulb is three wires. Usually I don't worry about the ground wire, since the bulb only uses the white and black to power up.

The new ballast has this connnector, so I had to cut it off to connect it to my lights.

Ready to go.

I use these water resistant wire nuts. They contain some type of gel internally, and are generally safer around moisture.

The new ballasts up on the light rack.

Here's the end result. 10,000K lighting.

Turn them off and on again, 20,000K lighting.

To the naked eye, I could see how much brighter the tank is. I did some initial PAR measurements, which I blogged about on Melev's Reef: http://melevsreef.com/blog/comparing...bulbs-06152014

I'll be doing some more measurements in the next week, and am reducing the total lighting period significantly to avoid burning the corals with the sudden intense PAR from the 400w bulbs. The middle of the reef should essentially be unaffected although a new bulb does put out more light than one that is 10 months old.

The VHOs were replaced today as well. All new lights across the reef as of now.