Design Pool Lighting

[MNicolai]

For a project I'm working on, I need to shine at least (6) ColorBlast12's into a custom-built pool as side lighting. The pool is 8' by 14', 20.5" deep. It will have continuous sheet of EPDM as a liner, with 3/4" plywood sides and floors, supported by additional bracing and structures.

I have two options I can think of. One is to cut holes into the EPDM at 10.25" from the surface, sandwich the EPDM with Plexiglas from either side using roof cement, and provide additional leak-protection with layers of aluminum flashing. Then place the CB12's such that they shine through these portholes. A couple people have expressed concerns that I might not be able to get a watertight seal though. If that's the case when we flood the pool, time will not be an issue to fix it, but I would need to drop another $400 on a second sheet of EPDM.

The other option that I have is to place the CB12's at the top of the pool, enshrouded using careful scenery placement, use mirrors like periscopes to shine the lights into the pool, then use additional underwater mirrors to guide the light once it's underwater. Granted, the mirrors would need to be made without glass to prevent a broken glass hazard to cast members during the show.

Either option is possible for me to try, but because of the labor and costs of executing either of them, I only have one shot at this. If the option I go with doesn't work, I have to cut my losses and start again, probably costing the production an additional $450 or so.

If you were the scenic/lighting designer, which route would you go with?

 

[derekleffew]

I'd prefer to use the Submersible LED Light Fixture - Philips Color Kinetics C-Splash 2 ,

but if budget is an issue (isn't it always?), I'd try option #1: CB12's behind Lexan. I think you'll lose too much intensity bouncing off two mirrors and the water. Note also for the light to be seen, you need to "cloudy up the water." Compressed air through a soaker hose works well for this. People who work for O and LE RÉVE call this "aquatic masking." See also Lake of Dream at Wynn Las Vegas.

And of course, whatever you go with, WILL be protected by a GFCI, right?

 

[MNicolai]

My concern is primarily accessibility with those. I can rent CB12's from all over the place, but those I can probably only buy. I'll make some calls, but I imagine I won't have a ton of luck. Each of those is also only 40% of the luminosity of a CB12.

 

[derekleffew]

So use 4,000 of 'em!

 

[MNicolai]

Haha! I can already imagine the look on the director's face when I turn on them all on.

"You said you wanted underwater lighting..."

 

[Corbettlight]

How would the DMX on the Color Kinetics C-Splash be connected underwater with no leakage?

 

[MNicolai]

DMX only has to go as far as the power supply. The power supply then carries the electrical to the fixtures via 60' cables that are permanently terminated at the fixtures with complete waterproofing where the wires enter the fixture.

 

[highschooltech]

The C-Splashes are pretty cool we just demoed a few at work based on an owners crazy request. They work fairly well, even though they are a little dim, and everything they need is in one wire that connects back to the power supply. They would be great for your application but you'd probably have to buy them and they're fairly expensive based on the quote we got.

 

[SHARYNF]

+1 for the Lexan solution

I would look at routing out a channel in the lexan so that you can in essence form a a gasket all around it and reduce the space between the lexan panels where the EDPM is

this is sort of like the insulated windows, where if the space between the glass sheets causes too much flex on the ends, then the seal breaks and you get moisture between the panels. If you have a sufficent about of "goop" in the channel that the flex for the thickness of lexan will not break the seal.

In addition I would make sure the the plywood behind the "window" was such that the lexan is supported. That you are trying to avoid is the water pressure causing the lexan to distort in such a fashion that starts to pull out the edpm. Make sure you have a sufficient thickness of lexan


IN an underwater submarine design that I a aware of, the lexan is not a sandwich, it is a single layer that is placed into a cutout in the Hull that is sufficiently deep to allow the lexan to be flush with the hull and then have a flange in side that is strong enough to support the force and provide the gasket support.

Basically the concept is again not to have a space between any layers that would allow for the force in the middle of the panel to be able to raise the edges sufficient to break any water seal. Fortunately the closer you are to the surface the better you are. The Thicker the Lexan is and the smaller the panel the less it will flex.


Another thought that you might try if the design would allow it is to have the lights on the surface submerged facing down. Then your force that you are dealing with is the weight of the fixture assembly with its water proof "box" and not the force from weight of the pool of water.

It does not take a lot of light to completely light a pool of water. Just think of a swimming pool light

Sharyn

 

[PeteEngel]

hmmmm...so many things to consider doing a water show and so little time/budget. safety first. any time you consider breaking the integrety of the pool liner for the sake of visibility you risk seal failure. safety first. at "O" they use various forms of lighting, side light via a tunnel with 4" plexi(or similar) permenantly mounted in the pool wall. i'm guessing this lghting is to illuminate what is in the water as opposed to creating a visual concept on it's own? what you are trying to achieve can lead to different source types.
if you are going with side light to illuminate what is in the water then the submersable LED's (or incandescent equivalent) is the route to go. remember, thewater surface acts as a partial mirror, both from above and below. the more of an angle your light hits the surface of the water, the more it will reflect. the more direct angle the more light passes past that plane.
aquatic masking...this effect creates bubbles that act as individual planes of air/water, just like the surface of the pool, and as light hits the bubbles light reflects and refracts. you get to see the light but your light will not extend as far into the water as with no masking, effectively making a wall where light mostly doesn't pass at a certain distance depending on the frequency of the light. (red passes farther than blue). any particles in the water will reflect light, even bubbles on the surface, so chose your effect wisely. besides, creating masking is a pain in the..

have fun, and most of all...

Safety First!

Please familiarize yourself with any and all pertinent Electrical Codes for electricity and lighting around pools. a nice idea can suddenly turn into a liability nightmare. NOTHING is worth injury or death, especially art.

 

[starksk]

Another +1 for the lexan option.

When I was doing this show, we were going to do almost exactly what SHARYNF suggested before the fixtures were cut for budget. I agree that two layers of plexi is overkill. I would recommend that you cut the liner in a fashion that you are not removing the excess material but just folding it over the edge of the 3/4" ply hole. Then, having routed a gasket groove as SHARYNF suggested, I would use a gasket and then screw the Lexan directly to the 3/4" plywood and seal the entire assembly using caulk. The caulk is probably overkill, but it is a cheap preventative measure.

I also agree with PeteEngel in that you should be aware of the appropriate codes when it comes to fixtures in and around wet locations. GFCI at the minimum, but also be aware of the cabling requirements of your local AHJ.

As for color loss, your entire pool does not have enough water to significatly affect which wavelengths will get filtered. Red would be the first to go, and even then it takes about 20-30 feet of water before you notice any significant change. (Yay for SCUBA paying off in a lighting application)

Please post pictures of your process after you decide which direction you are going. This sounds (and probably looks) like a fun project.

____________
~Kirk

 

[JChenault]

I would probably lean toward the porthole approach - but the first thing I would do would be to build a mock up in the shop to test my ability to make a waterproof porthole. This way you can have some confidence that it will not leak ( or at least not leak too badly that you can't handle it).

My understanding of the CK units is that you can get a flavor that takes 110V power to the head, or ones with a remote power supply. For this application I would recommend the later ( IE don't use a data enabler - use the transformer/data enabler).