Transitioning from LED to MH

[EMeyer]

Hi all,

On one of my tanks, I'm switching from LEDs to MH/LED. I'm thinking about the acclimation / transition, and wondering if anyone here has experience making this change.

Previously the tank was lit with modified black box LEDs, at about 150 blue PAR for ~8 hours with ~6 hours of 200 PAR (blue+white). It has acros and a few surviving montis. (Montis hate me)

Since MH intensity can't be adjusted my thought is to start with a very short photoperiod (perhaps 1-2 hours) on the MH and ramp up to ~6 hours over a period of about 2 weeks. But this is just shooting from the hip. Does anyone have experience with this?

Thanks for any advice you can share!

 

[JoshH]

@Fin @NY_Caveman any thoughts here?

 

[biecacka]

You can use a shortened photo period as well as raise your lights and or use something as a diffuser to cut down the intensity.

Corey

 

[EMeyer]

Thanks, yeah, I've been considering adding a diffuser during the transition. Since I use glass lids I may just get the glass nice and dirty with saltwater, that drops intensity by about 10% IME

Biggest thing I'm worried about is just the raw intensity, these corals have never seen the 400+ PAR I am expecting from this light based on my last 250W MH... I hope I can find the balance between not frying them and giving them enough to survive. Think I'll err on the low side, maybe start at 30 minutes MH...

 

[A. grandis]

Hi all,

On one of my tanks, I'm switching from LEDs to MH/LED. I'm thinking about the acclimation / transition, and wondering if anyone here has experience making this change.

Previously the tank was lit with modified black box LEDs, at about 150 blue PAR for ~8 hours with ~6 hours of 200 PAR (blue+white). It has acros and a few surviving montis. (Montis hate me)

Since MH intensity can't be adjusted my thought is to start with a very short photoperiod (perhaps 1-2 hours) on the MH and ramp up to ~6 hours over a period of about 2 weeks. But this is just shooting from the hip. Does anyone have experience with this?

Thanks for any advice you can share!

All depends on what wattage you are running now and what wattage you will be running those halides...

 

[EMeyer]

All depends on what wattage you are running now and what wattage you will be running those halides...

Currently its LED, at 150-200 PAR. The Halides are 250W. In the past I recall getting about 400 PAR at relevant depths from a 250W halide...

 

[WVNed]

I went from a ReefBreeders Photon V2 to Hamilton fixture with 2 250w and 4 T-5s.
No acclimation was required. I started the MH at 5 hours a day and quickly increased it to 8. I ran the T-5 10 hours,
I had it sitting right on the tank with the legs.

Then I went back because I bought the Hamilton fixtures for the new tank.

 

[A. grandis]

Currently its LED, at 150-200 PAR. The Halides are 250W. In the past I recall getting about 400 PAR at relevant depths from a 250W halide...

Remove the LEDs and put the halides. Set time for 2 hours a day for the fisrt week and increase 1 hour per week and you should be fine. That's the way I did when I went from T5s to halides. I still have 4 T5s for 9 hours a day since the beginning, with the 2 X 250W 20K halides for 5 hours a day now.
Doesn't matter if you use T5s with the halides or not. That will be the safest way to prevent anything to happen because of the halides.
When you change bulbs give it like 2 hours off the first week and increase back to normal by 1 hour per week til you get to what you want.
Congratulations! Your corals will love you forever!

 

[Chessmanmark]

Why are you using glass lids? They inhibit gas exchange and may retain excess heat from the MH. Screening is more prudent IMO.

What is the new lighting fixture that you are changing to?
SE or DE?
How much wattage?
What kind of bulb do you want to use?
How will you mount it over the tank.
Also, what are your tank dimensions?

I have two LumenBrights pendants running 250wDE on a 90 gallon tank. The way they hang it is easy to raise and lower them. I like the Reeflux 20k bulbs, but they cost more. Most years I use Ploenix 14k bulbs because they are cheaper.

 

[EMeyer]

Remove the LEDs and put the halides. Set time for 2 hours a day for the fisrt week and increase 1 hour per week and you should be fine. That's the way I did when I went from T5s to halides. I still have 4 T5s for 9 hours a day since the beginning, with the 2 X 250W 20K halides for 5 hours a day now.
Doesn't matter if you use T5s with the halides or not. That will be the safest way to prevent anything to happen because of the halides.
When you change bulbs give it like 2 hours off the first week and increase back to normal by 1 hour per week til you get to what you want.
Congratulations! Your corals will love you forever!

Thanks, great to hear from experience on this transition! I am looking forward to it but just didn't want to burn them with too much, too fast...

Why are you using glass lids? They inhibit gas exchange and may retain excess heat from the MH. Screening is more prudent IMO.

Respectfully disagree on the lids - between my skimmer and the returns, I'm confident my system is way beyond saturated for gas exchange. I use glass lids specifically to prevent excess evaporation; this allows me to take them off in the summer to cool the system by evaporation. In the winter, I can leave them on to minimize heat loss.

After experimenting with various lids over the years I now religiously only use glass.

But I do agree that if the system is limited for gas exchange (e.g. a tank without sump or skimmer) glass lids could cause problems.

What is the new lighting fixture that you are changing to?
SE or DE?
How much wattage?
What kind of bulb do you want to use?
How will you mount it over the tank.
Also, what are your tank dimensions?

I have two LumenBrights pendants running 250wDE on a 90 gallon tank. The way they hang it is easy to raise and lower them. I like the Reeflux 20k bulbs, but they cost more. Most years I use Ploenix 14k bulbs because they are cheaper.

250W over a 40 breeder. I plan Phoenix 14k, I liked them in the past.

Unfortunately my system doesnt have room to acclimate by slowly lowering the light. I wish, I really think that would be the ideal way to go.

Thanks again!

 

[EMeyer]

Update: gave them 1 hr yesterday, since theyd already had ~2 hours of full LEDs by the time I got around to setting up the lights. Doing 2 today, 3 tomorrow, etc.

PAR measurements show only 175-200 at the tank bottom which is great, I'm less worried about light stress now.

First impression: I forgot how beautiful MHs are. When the lights come on, it is the Rising of the Glorious Sun. Viewing the corals looks just like snorkeling on a shallow reef. The only bad thing is that all my LED tanks look so fake now in comparison!

which reminds me, Im gonna go look at my MH tank some more now.

 

[DesertReefT4r]

Very coral I have in my reef has come from a LED lit system and or was fully grown under LED. I run just 250w MH. Corals transition over just fine, there is alwaus some color shifts but health has never been effected from the change in light type.

 

[jda]

I have an older oceanic with a glass center brace... 35% less PAR under that part with the MH. I would remove the glass.

I just put MH on. If you are worried, then start with 4-5 hours and then raise them up.

Light and acclimation burn is more of a LED thing than a MH thing.

 

[Backreefing]

I’m also going from led to metal halide ( soon ) during a tank upgrade. A 37 to a 90 . I’m building the stand and canopy right now .
My plan was to slip a window screen between the lights and aquarium. For a week or two.

 

[EMeyer]

I have an older oceanic with a glass center brace... 35% less PAR under that part with the MH. I would remove the glass.

I just put MH on. If you are worried, then start with 4-5 hours and then raise them up.

Light and acclimation burn is more of a LED thing than a MH thing.

I checked, less than 5% loss of PAR. I imagine your glass brace is much thicker than my thin glass lid.

 

[EMeyer]

Just wanted to follow up on this in case its useful for anyone else pondering the transition.

Its been a couple weeks and my corals showed no signs of stress at all. I ramped up from 1 hour to 6 hours per day gradually over the course of about a week.

This is a frag tank with acros and montis. Funny thing, the montis had previously preferred lower light (100 PAR) under LEDs and done badly under higher PAR. But under the MHs, theyre finally recovering. I see coenosarc again on the previously grey areas.

For the acros, it goes without saying. I see thick tissue, no paling at all, lots of polyp extension. Theyre loving it.

Visually I love it, and stand by what I said earlier. Every time I look at my LED tanks they just look fake now.

Then I have to replace a socket on the MH, or a bulb starts flickering for some unknown reason, and I miss the stability of LEDs

Still, its the Glorious Sun. I am glad I switched, at least for a grow tank.

 

[Bubbythebull]

Imo, the photo period isn't what shocks the corals..it's the intensity. Diffusers or hanging the light higher would do the trick. Of our, use a part meter to co firm or levels every step of the way. I've known many to go from halides to led..never the other way around

 

[EMeyer]

Oh I agree, the intensity is what worried me. But since they arent dimmable and I dont have room to adjust the height, photoperiod was all I could think of to minimize stress.

 

[Bubbythebull]

I think a shorter photoperiod but with high intensity will still shock coral....so I don't think that alone will work...I've had corals...all of a sudden not open up for weeks..and I realize after the fact..it's because I increased intensity too fast

 

[Bpb]

I went backwards. LED to T5’s to MH