PFO pendants - height from water?

[Myka]

Hey guys, a year and half after setting up my 90 in Saskatoon I am finally getting around to building the canopy!

I have a couple of PFO mogul perpendicular "Optimal" pendants that I'm going to use. I bought them used awhile back so I don't have a user manual and I can't find one online. Does anyone know the manufacturer's recommendation for height off the water to mount these? The tank is 48" long and 18" wide.

They are this model:

[Skimmerking]

Mindy I used to use a pair of them and had them around 12" from the water

[Myka]

Ok thanks! I'm trying to decide somewhere between 8-12". I was looking at a light distribution graph comparing this reflector at 6", 9", and 12". Going by the width of my tank I think I'm going to mount them 9-10". If my tank was 24" wide I think I would lift them up to 12".

[mark]

When planning my hood for 250W DE pendants I contacted a couple of companies for height above water. From Hamilton for their Reefstar pendants they recommended 8" above water, from PFO and their mini-pendants they said 5 ".

I ended up placing the bottom of my PFO fixtures 5.5" above the water.

[Myka]

Thanks Mark! DE is different height than SE though, and the PFO mini pendants are hung much lower than typical because their light spread is quite small.

I decided I'm going to build the canopy to accommodate 12" above the water, and I can adjust the height by chopping down the upright piece. I'm going to build the canopy so the pendants partially stick out the top to increase air movement around them.

[sphelps]

Personally I think 12" is too high for a PFO reflector on a 90 gallon, 6" would be better and I believe that is what PFO recommends. Remember when you're looking at light distribution diagrams, the 6" plot would be the distribution at the water surface which isn't that relative since your corals are obviously lower.

[Myka]

Originally Posted by sphelps

Personally I think 12" is too high for a PFO reflector on a 90 gallon, 6" would be better and I believe that is what PFO recommends. Remember when you're looking at light distribution diagrams, the 6" plot would be the distribution at the water surface which isn't that relative since your corals are obviously lower.

Good call on the plots Steve! I think 12" is too high too considering it is only 18" wide, but it's pretty easy for me to make the canopy to have adjustable height fairly easily and I would like to be able to see them at different heights. I was just taking measurements though, and I don't want my canopy to be overly tall, so I don't think I'm going build to accommodate 12" because that makes for a really bulky looking canopy. I'm going to build to accommodate 8", and go from there. I'm a bit worried about splash causing bulb breakage at only 6" since I don't have any glass between the bulb and the water...? I am planning that I will probably like them about 8", but I haven't used these particular pendants before.

My current DEs are like 2" off the water...hehehehe.

[sphelps]

I've had SE uncovered bulbs 6" from the water before without any problems, I've splashed bulbs before by accident as well and they never broke, I think it's harder than most might expect.

I agree with your canopy ideas, you don't want something ridiculously high. Have you considered building a canopy as low profile as possible and then hanging it?

[Myka]

I would love to hang it, but I have some talented jumpers in my tank so I need a barrier. Maybe I will try the 6" height then...then I can keep my canopy only 6" high too which would be nice. I have a 2-bulb Tek retrofit to mount in there too.

[sphelps]

Even with a canopy some jumpers just can't be stopped, I know I've had some jumpers jump within closed canopies and getting stuck on the bracing or on top of fixtures and other objects.

I find the best solution for jumpers is a netted lid, building a lid from aluminum screen frame and plastic netting is pretty easy, cheap and effective. Just something to consider.