Returning to Metal Halide from LED

[1979fishgeek]

hey guys

I want to change to a 250w metal halide 20k but my corals are currently under 165w LED and there are a few Acropora really close to the surface.

What's the best way to acclimate them from the LED to the stronger MH? My acro can't be moved and I don't want to bleach/shock/kill them.

 

[Maritimer]

You could try placing a few (or several) layers of plastic window-screening between the lights and your corals - lay them on the screen-top, if you have one. Each week, remove a single layer, and . . .

~Bruce

 

[saltyfilmfolks]

With out a par par meter it's tough. You can use a Lux meter and we can work out the close conversion numbers to estimated the par of both.

But yup Bruce has it right. Screening material, also you can use time and slowly add more to your photoperiod.

 

[JaimeAdams]

You could also start with hanging your lights higher and every week lowering them a bit, that is what I did when I added my newer lighting.

 

[1979fishgeek]

You could try placing a few (or several) layers of plastic window-screening between the lights and your corals - lay them on the screen-top, if you have one. Each week, remove a single layer, and . . .

~Bruce

That's a good idea!

I don't have window screening, but do have a load of clear acrylic sheets stacked on top of each other they would be over 10cm thick. Some light would pass through but not all, would that be ok?

 

[1979fishgeek]

You could also start with hanging your lights higher and every week lowering them a bit, that is what I did when I added my newer lighting.

I am restricted by height,but that be great idea to.

 

[Maritimer]

That's a good idea!

I don't have window screening, but do have a load of clear acrylic sheets stacked on top of each other they would be over 10cm thick. Some light would pass through but not all, would that be ok?

Better than nothing... Be aware that the acrylic will interfere with oxygen reaching the surface of the water, and that the bottom sheet may begin to grow unpleasant amounts of algae. Also, it's going to be heavier, if that makes a difference.

~Bruce

 

[1979fishgeek]

Better than nothing... Be aware that the acrylic will interfere with oxygen reaching the surface of the water, and that the bottom sheet may begin to grow unpleasant amounts of algae. Also, it's going to be heavier, if that makes a difference.

~Bruce

I was going to keep it clear of the water, but that's still a good point.

 

[andrew james]

You could leave them on for less time.

 

[Maritimer]

I was going to keep it clear of the water, but that's still a good point.

Humidity built up underneath can be sufficient. Every tank I've ever had with a glass or acrylic lid ... has grown algae on the bottom of the lid, though they weren't immersed in the water.

~Bruce

 

[1979fishgeek]

Humidity built up underneath can be sufficient. Every tank I've ever had with a glass or acrylic lid ... has grown algae on the bottom of the lid, though they weren't immersed in the water.

~Bruce

That's very true, going to have to clean it a lot.
Thanks

 

[bpseal]

I am too switching from LED (Kessil/T5 to MH/T5. What is a good height for having your fixture above the water surface? Thank you much!!

P.S. I already bleached some coral after 2 days so anything helps! Although I stupidly had them only 4.5 inches above the surface. Thanks all

 

[ShyShy]

Just Curious, but has anybody tried using neutral density color filters for acclimation purposes. I use them in the stage and film lighting industry all the time, but never really thought about their application in aquarium light reduction until now. They are heat shielded and come in almost any shade, value, or hue. $7 for a 24"x24" sheet and you can foil tape them directly to the fixture to avoid humidity build up. I don't know. Maybe it's already been thought of/attempted. Just food for thought. Would be interested it what more aquarium lighting versed people think.

 

[mcarroll]

@ShyShy

A) if you have no light meter, then you're guessing at which light is brighter and by how much
B) if you're guessing, then you really can't confidently articulate a plan to get where you want to be
C) if you can swing a $12 lux meter, then taking your measurements* and using the dimming on the LED to close any gap between the lights as much as possible BEFORE switching
D) it's possible that after you close that gap any remaining difference will be insignificant – but you will then be able to formulate a good plan forward since you will know how much light is coming from each fixture. ​

* It can be interesting to do lux-to-PAR conversions, so do them if you have the time and inclination. But for this purpose I wouldn't consider converting necessary – just working with the numbers that come from the lux meter should be sufficient guidance.