600w MH?

[GarrettT]

Why are you so worried about PAR? How funny when people try to bring that "LED thing" to the halide world. Trust me... If you have a 400W 14K Hamilton over a 30" deep tank, that should be enough. You do not need a 600W or a 1000W. Even if you are using an electronic ballast for those 400W Halide bulbs, because that's what Hamilton suggests anyways, right? What you need to do is to make sure that the reflectors you are using are offering proper distribution of those photons for your system. You don't have to worry about PAR. And yes, please get a transparent screen over the tank. That makes a difference. Enjoy your halides!!

My 400w Hamilton only gives me 185 par at mid level on my 24'' tall tank. Are you saying this is enough for Acropora?

Edit: The transparent ''clear'' net screen didn't increase par on my tank compared to the black.

 

[jda]

Cozumel is a spread reflector, so they don't punch super deep. For a wider tank and deeper tank, they are good choices. For a narrower tank, some of the 14x14 or 16x16 pendants are often the better choice if you want deeper light penetration on tanks that don't need such wide spread.

Some stagger spread reflectors with punch ones in larger tanks and align their rock structures for the lights. Higher rocks under the spread and lower under the punch. You can also plan your high light acropora to be higher in the rockwork.

I had to use a cozumel over a 24x24x12 frag tank and let is spread because I could not handle the 900 PAR from a smaller reflector in that shallow of a tank.

185 PAR is fine for a lot of acropora if you run for 8+ hours. This is where DLI comes in 185 PAR for 10 hours is 1850 which is similar to 300 PAR for 6 hours for 1800. This is mostly theoretical still, but it seems to work in most cases where light is not super excess and time frame is not too short or too long (like 1800 PAR for 1 hour or 100 PAR for 18 hours).

 

[GarrettT]

185 PAR is fine for a lot of acropora if you run for 8+ hours. This is where DLI comes in 185 PAR for 10 hours is 1850 which is similar to 300 PAR for 6 hours for 1800. This is mostly theoretical still, but it seems to work in most cases where light is not super excess and time frame is not too short or too long (like 1800 PAR for 1 hour or 100 PAR for 18 hours).

Thanks for the post. This helps a lot.

 

[jda]

I was planning using the Cozumel Suns Large Pendant 20x20x9 and using 4 36" T-5's for my 96x40x36 tank... Are you suggesting that they are not enough power for a deep tank?

With a tank this size, I strongly suggest that you go to ReefCentral and find Copp's thread in the SPS forum and browse through it, if you have not already. He has a tank large tank too and you might get some ideas about lighting or something else from him. Even if you don't get anything useful, then it is still worth the time to have a look.

 

[jda]

There are many people keeping acropora under 200 PAR from LEDs and the LEDs don't even produce the output from UV and some IR that the halides will give the corals. 200 PAR from LED is probably close to 200 whereas 200 PAR from a MH is more than that since the meter and sensor cannot measure beyond the visible spectrum.

I would not put your expensive, really nice stuff down that low, but that can be a great place for your dragons, some encrusters, stags that will reach up, etc.

 

[GarrettT]

Would a lower kelvin bulb increase par much? In regards to switching from a 14K to 10K bulb?

 

[jda]

Oh yes. Color shifts a lot too, of course.

I cannot get the reefs.com lighting guide to show a graph on my computer, but if it works on other platforms, you can compare something like a Hamilton 10k to a Hamilton 14k on an electronic ballast to see the difference - change the spectrum from 350 to 800 and then look at the ppfd ratings... the 10k isa good bit more. To be fair the Hamilton 14k is not an output monster, but the 10k is still more than a best-of-breed type of 14k bulb.

I think that the Hamilton 10k is a nice bulb. Crisp white with good pop. Most think that it is not blue enough. Some really love it with some blue strips or T5s.

This is not a direct comparison, but it can give some idea... Iwasaki 6500k at 189 ppfd compared to the Radium 20k (more like 14k for these purposes) at 85. Notice that most of that increased output is from 475 to 700, so it will look more yellow and green. A 10k bulb will usually have a blue spike still and it is not like this Iwasaki, but I just wanted to share the output difference.

 

[A. grandis]

My 400w Hamilton only gives me 185 par at mid level on my 24'' tall tank. Are you saying this is enough for Acropora?

Edit: The transparent ''clear'' net screen didn't increase par on my tank compared to the black.

jda explained already.
Metal halide application depends on: wattage / type of reflector / spectrum ("whiter" light = more PAR) / DLI, to get the results you want. That's why choosing the right equipment for that optimal balance will give you the best results. Having the Cozumel will spread light well, but you will need to have that light available for the right period of time daily (DLI). Punching more intensity in a restricted area with a narrower type of reflector will also limit your hours/day ration to avoid unnecessary excess light. It's the balance that counts.
That said.. if you have the proper spectrum with your Cozumel and leave it on enough time during the day, you will get those Acros to grow amazingly!
Post pics, if you can. Cheers!

 

[YOYOYOReefer]

Ive ran mostly 400 radiums (20K) on pfo hqi ballasts (so slightly overdriven bulbs)

ive had tanks 11 inchs deep and 30 inches deep, never wanted for more lights. What ballast are you driving it with?.

 

[GarrettT]

Post pics, if you can. Cheers!

Don't take photos very often. Here are two that are available for when I initially set everything up. Only had supplemental lighting on at the time. Only difference is that I now have a 3rd OR3 bar in the front. The lighting equipment pretty much covers the entire top of the tank.

 

[GarrettT]

ive had tanks 11 inchs deep and 30 inches deep, never wanted for more lights. What ballast are you driving it with?.

Icecap 400w selectable wattage electronic

 

[wjgeese]

Cozumel is a spread reflector, so they don't punch super deep. For a wider tank and deeper tank, they are good choices. For a narrower tank, some of the 14x14 or 16x16 pendants are often the better choice if you want deeper light penetration on tanks that don't need such wide spread.

Some stagger spread reflectors with punch ones in larger tanks and align their rock structures for the lights. Higher rocks under the spread and lower under the punch. You can also plan your high light acropora to be higher in the rockwork.

I had to use a cozumel over a 24x24x12 frag tank and let is spread because I could not handle the 900 PAR from a smaller reflector in that shallow of a tank.

185 PAR is fine for a lot of acropora if you run for 8+ hours. This is where DLI comes in 185 PAR for 10 hours is 1850 which is similar to 300 PAR for 6 hours for 1800. This is mostly theoretical still, but it seems to work in most cases where light is not super excess and time frame is not too short or too long (like 1800 PAR for 1 hour or 100 PAR for 18 hours).

haha...thats like saying you can cook a turkey at 350 degrees for 4hr, or 700 degrees for 2hr!! there is such a thing as photoinhibition

 

[jda]

No, not with applicable DLI. Did you read my post carefully, I specifically addressed too much light and too long or short of photoperiods being not good.

Ad far as I know, I have seen no science on cooking turkeys as there is on DLI, so I doubt that they are the same thing.

 

[t5Nitro]

How is your tank and lighting coming along? I just got the 400W M135 ballasts x2 delivered today. Waiting on the actual pendants and 20K radium bulbs to come.

I will have a very similar setup. I've got an OR3 blue plus bar for the front and a reef day plus bar for the back to run a 12 hour photo period, off during 6 hours of planned MH time in the middle.

If the cozumel sun at 12" water depth 20K bulbs are truly giving only 185 PAR, that gives me an estimated ~4 Mol photons from the halides over 6 hours.

Running the OR3 bars x2 (~100 PAR each) at 6.5 hours daily run time would provide about 4.7 Mol photons per day.

Total daily Mol photons with the PAR you suggested with the 400W 20K halides at 6 hours per day with 2 OR3 LED bars at 6.5 hours per day gives the tank 8.7 Mol photons per day with that photoperiod.

That does seem quite low, but maybe it is good enough to grow acros? With my current 8 bulb T5 fixture, its 11.5 Mol photons in an 8 hour photo period with all 8 fired. But then I have 2 additional hours of just 2 bulbs and another hour or so of just LED bar. You can see the DLI from the current setup would smoke the halides.

 

[GarrettT]

Keep in mind, with my measurement, the 185 par (MH only) was under 14K. With the 3x OR3's it's around 280-340. Now that's with all of them on at the same time. I run my two OR3 blue plus from 7:30-7:30. MH and OR3 blue sky from 10:30 to 5:00.

Corals are doing well. phenomenal coloration, but ok growth. Still in the encrusting stage, but they're encrusting well. I've been dealing with dinos, and as such, its been affecting my acro's a little. Lots of tank maneuvering, which has impacted the overall stability of the tank. Can't really blame that one the lighting.

edit: I should note, that I haven't lost any of my 20+ acros. None of them are brown, which would indicate a lack of lighting.

 

[t5Nitro]

Thanks for the update. I will run 2x 400 watt 20K radium on M135 to start. Originally anticipated halide time 6 to 7 hours and blue plus and reef day plus OR3 bars flanking the halide photoperiod for 3 hours on either end for a total 12 hr photoperiod.

Will see how the numbers look when I actually get it all set up.

 

[GarrettT]

Nice. Keep us updated. Interested to see your experience.