T5 Fixture Mounting Height

[FishyDP]

Looking for advice on how high to mount my T5 fixtures above my water line. They are 4 bulb fixtures, 2x 36" units going over a 150g 72x18x27 tank. Currently I am keeping softies and LPS, but plan on starting SPS. Not high end fixtures, the are Odyssea T5 Quad Timers. Will be purchasing all ATI bulbs. Supplementing with lower PAR leds.

 

[RobZilla04]

How high can you mount them?

Heights range across the hobby from 8" to 24". IMO higher gives better spread and spectrum blending. Also consider allowing room to reach into the tank for maintenance so mount accordingly.

 

[Gablami]

The rationale for better spread and spectrum blending applies more to leds, not t5s. You don’t want to go that high because 4 bulbs is not that much light for an sps tank. You mention that the t5 will be doing the heavy lifting.

I have 4 bulbs over my 5 foot tank, along with 2 kessil ap700. With the kessils at 20% at peak, with all 4 bulbs on, my par is about 250 at the midpoint of the tank (12 inches down). The t5 are 8 inches above water.

So the answer is, it depends. It depends on whether your LEDs can supplement enough to give you sufficient par for sps corals. It depends on whether you have enough access to the tank at whatever height you are thinking. It depends on light bleed into the room. But don’t hang too high if your leds aren’t going to be able to pick up the slack, because hanging height drops par quickly.

 

[Dom]

How high you mount your light above the water line will depend on the depth of the tank, the area you want to cover and the intensity you want to achieve.

I use a lux meter with my tanks and have a goal of 8-10K lumen at the deepest part of the tank.

So in your case, I would say to mount your light at a height which will give 8-10k lumen at the deepest points in your tank and cover to all 4 corners.

 

[dutch27]

27" is a deep tank. Over my old 120g (24" deep) I had an 8-bulb fixture that sat around 6"-8" off the tank and could grow SPS in the lower part of the tank. I would go as low as you can while still being able to work in the tank. Personally I'd go no more than 8". Keep in mind PAR doesn't drop off linear to depth, it drops faster as you go deeper, so mounting height can have a major impact on PAR at the bottom of the tank.

 

[FishyDP]

The rationale for better spread and spectrum blending applies more to leds, not t5s. You don’t want to go that high because 4 bulbs is not that much light for an sps tank. You mention that the t5 will be doing the heavy lifting.

I have 4 bulbs over my 5 foot tank, along with 2 kessil ap700. With the kessils at 20% at peak, with all 4 bulbs on, my par is about 250 at the midpoint of the tank (12 inches down). The t5 are 8 inches above water.

So the answer is, it depends. It depends on whether your LEDs can supplement enough to give you sufficient par for sps corals. It depends on whether you have enough access to the tank at whatever height you are thinking. It depends on light bleed into the room. But don’t hang too high if your leds aren’t going to be able to pick up the slack, because hanging height drops par quickly.

Makes sense. My LEDs are not extremely strong. I am hoping that they will add just enough enough par for my zoos/acans towards the bottom, and give everything a little "pop" in color. I intend on placing any sps I get towards the top, right under the T5s. My tank is fairly deep, so I am thinking of mounting the t5s about 3" off the water line..I know this is very close, do u think I will have issues with salt creep this close?

 

[FishyDP]

27" is a deep tank. Over my old 120g (24" deep) I had an 8-bulb fixture that sat around 6"-8" off the tank and could grow SPS in the lower part of the tank. I would go as low as you can while still being able to work in the tank. Personally I'd go no more than 8". Keep in mind PAR doesn't drop off linear to depth, it drops faster as you go deeper, so mounting height can have a major impact on PAR at the bottom of the tank.

This is good to hear, if you could grow sps in the middle of your 24" tank with 8 bulbs at 6-8" mounting height, I am thinking that I should be fine with 4 bulbs mounted around 3-4" above the water?..if I am placing my sps in the upper third of the tank. A big part of my goals are to be able to have lower light colonies basically on the sand bed, or close to it. I wish I had PAR meter..

 

[madweazl]

This is good to hear, if you could grow sps in the middle of your 24" tank with 8 bulbs at 6-8" mounting height, I am thinking that I should be fine with 4 bulbs mounted around 3-4" above the water?..if I am placing my sps in the upper third of the tank. A big part of my goals are to be able to have lower light colonies basically on the sand bed, or close to it. I wish I had PAR meter..

Unless there is a shield to keep water from splashing up on the lights, I wouldn't mount it any closer than about six inches above the water.

 

[RobZilla04]

Makes sense. My LEDs are not extremely strong. I am hoping that they will add just enough enough par for my zoos/acans towards the bottom, and give everything a little "pop" in color. I intend on placing any sps I get towards the top, right under the T5s. My tank is fairly deep, so I am thinking of mounting the t5s about 3" off the water line..I know this is very close, do u think I will have issues with salt creep this close?

What brand/model LED fixtures do you have?

3" is extremely low and you'll have more probs with moisture & splashing than salt creep. Spectrum blending is primarily a concern with LED's yes, however a four bulb fixture with three or even four different bulb colors, blending is still a thing. How high are the LED's mounted?

FWIW I'm running 4 Kessil A360W-E and a two bulb LET T5 at around 8" off the water. Granted the LED's are the main driver of light intensity, the T5's do put out a ton of light. Never measured with a meter. Still waiting for the rentals to be in stock @ BRS.

 

[Gablami]

I feel like 3” is too close. Unless you have a splash shield like the sunpower, you can easily get splashes on your reflectors which can degrade the par slowly. But I’ve never had it at 3”. Maybe others can comment. I still get have some splash on my reflectors at 8” and I just live with it.

3” from the water just seems to close for comfort (personally) for an electrical device.

 

[FishyDP]

Unless there is a shield to keep water from splashing up on the lights, I wouldn't mount it any closer than about six inches above the water.

I should have mentioned, yes there are splash guards on the fixtures. Would you recommend mounting them at around 4" since they have splash guards? They are very thin, so I am hoping not to lose too much par.

 

[FishyDP]

What brand/model LED fixtures do you have?

3" is extremely low and you'll have more probs with moisture & splashing than salt creep. Spectrum blending is primarily a concern with LED's yes, however a four bulb fixture with three or even four different bulb colors, blending is still a thing. How high are the LED's mounted?

FWIW I'm running 4 Kessil A360W-E and a two bulb LET T5 at around 8" off the water. Granted the LED's are the main driver of light intensity, the T5's do put out a ton of light. Never measured with a meter. Still waiting for the rentals to be in stock @ BRS.

The LEDs are hipargero..they have been pretty good believe it or not. I have 3 of them mounted over my 125, which is my first reef tank started about 8 months ago. I keep zoos, acans, blastos, duncan's and hammers with them, with all corals in about the middle of the tank, which is 22" deep. Some of the zoos are stretching for light though, so I know I need to increase par for the new tank. I plan on mounting them at about the same height as the t5s. I paid around $180 total for the LEDs so I would like to put them to use..I saw that brs may be renting out par meters in the near future, that is pretty aswesome

 

[FishyDP]

I feel like 3” is too close. Unless you have a splash shield like the sunpower, you can easily get splashes on your reflectors which can degrade the par slowly. But I’ve never had it at 3”. Maybe others can comment. I still get have some splash on my reflectors at 8” and I just live with it.

3” from the water just seems to close for comfort (personally) for an electrical device.

They do have splash shields, so if I keep them clean it sound like I should not have too much par loss?

 

[RobZilla04]

The LEDs are hipargero..they have been pretty good believe it or not. I have 3 of them mounted over my 125, which is my first reef tank started about 8 months ago. I keep zoos, acans, blastos, duncan's and hammers with them, with all corals in about the middle of the tank, which is 22" deep. Some of the zoos are stretching for light though, so I know I need to increase par for the new tank. I plan on mounting them at about the same height as the t5s. I paid around $180 total for the LEDs so I would like to put them to use..I saw that brs may be renting out par meters in the near future, that is pretty aswesome

Those LED's are more powerful than you think. Not sure if they are going to be added to this testing project currently being worked https://www.reef2reef.com/threads/the-real-black-box-light-study.503052/ but in any case they alone can grow the listed corals you mention.

Supplementing with T5 will get you an amazing look with little shadowing. IMO you'd be fine mounting all lights at 8" above the water line.

 

[FishyDP]

I have been pleasantly surprised by the performance of these leds, and saw several reviews comparing them to the Hydra 26's. I am going to take a look at that study, thank you. I feel pretty decent moving forward with this lighting setup..

 

[T-5unsystem]

I recommend doing the following:

Blacken out your room, getting it as dark as possible.
Start with the light very high, like 18"
Note the "halo" on the floor, you should see a pretty distinct edge
Slowly lower the light until you "capture" this edge in the tank.

Even just capturing it slightly will cause a lot of light to bounce off the glass and get into the rock lighting the sides of corals that wouldn't otherwise get light if it was only coming down from the top.