Light Niche Algae?

[GaryParr]

I had to drain my pool this past Monday so the PB could fix a spot under the liner where, apparently, something just behind the dig-out had started to cave in. Some bad fill from the original development perhaps. Regardless, I got a brand-new 19k gallons of water trucked in on Tuesday. I started a short SLAM to make sure everything was good but two nights in a row I failed the OCLT with a 1.5 ppm drop in FC which is close but no banana. Hoping tonight is the charm.

Anyway, while reading the forum to make myself feel better by reading about how other people have the same "almost there, just keep swimming" problems, I noticed that almost everyone suggests scrubbing out behind the light niche. I figured it wouldn't hurt so I'll do that later today, but I got to wondering... doesn't algae need sunlight to grow? And, isn't it pitch black in a light niche assuming you actually have a light installed?

So my question... has anyone actually ever had algae growing in their light niche?

 

[cowboycasey]

Most everyone has had algae in there light niche... they love to live back there and grow with no issue and because it does not get scrubbed like the rest of the pool they continue to breed..

 

[Newdude]

There is zero circulation there are well. Just icky stagnant water.

 

[GaryParr]

Most everyone has had algae in there light niche... they love to live back there and grow with no issue and because it does not get scrubbed like the rest of the pool they continue to breed..

OK, so lived experience trumps my assumptions. I'll be scrubbing my light niche today.

But... how does it grow back there? Is the assumption that the light doesn't fit tight enough to block the light and enough sun gets through to allow it to grow? If this is the case... would fabricating a gasket to make it a true seal prevent future growth?

 

[cowboycasey]

I have lived it through helping people 9 years on TFP

Light gets everywhere, it reflects of things.. It is not totally dark and never will be.. You actually want more flow inside a light to get chlorine filled water back there to kill algae before it starts... but as stated above it get very little new water back there...

 

[Newdude]

And you wouldn’t want to seal it off because most lights need the water for cooling purposes. The fancy ones have finicky LED electronics to burn up and fail and my old skool 500W floodlight put off some HEAT.

 

[GaryParr]

Bah... that all make sense, but seems like such a stupid self-created problem. Can't have it sealed or else the light will get too hot and burn out, but it isn't open enough to allow for good circulation. Someone should invent a light niche that has vents around it and can be hooked to a return line. Force a flow of water through the niche so it never can become stagnant. Would just have to gasket where the wiring goes through to the run up to the transformer.

 

[Newdude]

Someone should invent a light niche that has vents around it and can be hooked to a return line. Force a flow of water through the niche so it never can become stagnant

Until *that* leaks and creates a new and improved headache. It’s always something my good friend.

 

[cowboycasey]

I am going with nichless lights that only have 1.5 inch pvc the light screws into, takes care of all that

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[GaryParr]

Until *that* leaks and creates a new and improved headache. It’s always something my good friend.

OK... so next step is to invent a never-leak pool design. I think it might involve a lot of dirt and planting grass.

I am going with nichless lights that only have 1.5 inch pvc the light screws into, takes care of all that

That's pretty cool... eliminate the problem. Unless you already have a niche of course...

 

[GaryParr]

And you wouldn’t want to seal it off because most lights need the water for cooling purposes.

So here is an interesting question... if the light (Hayward ColorLogic 4 in my case) is tight enough to prevent decent water circulation how does it dissipate heat from the back? I have a hard time imagining temperature differential would create enough movement to push the hot water out the top and cool water in the bottom sufficient to achieve any cooling effect. Is it just simply the water acts as a heat sink to transfer heat away form the light and into surrounding material?

If its just a heat sink then adding a gasket to block light (or even just block water contamination) while the pool is full (and thus the niche is full of water) would achieve the end goals, would it not?

 

[Newdude]

Is it just simply the water acts as a heat sink to transfer heat away form the light and into surrounding material?

It’s exactly heat sink like. The warmer light water is kept from getting hot by the much larger volumed pool water it touches. Errrr. Round about touches

If its just a heat sink then adding a gasket to block light (or even just block water contamination) while the pool is full (and thus the niche is full of water) would achieve the end goals, would it not

I’m no thermal expert but I’d imagine it would need to have similar heat transfer properties as the water to have the same results.

 

[GaryParr]

I’m no thermal expert but I’d imagine it would need to have similar heat transfer properties as the water to have the same results.

I'd imagine the light housing and retainer ring would be the largest surface area between front and back of the light, no? What little open exposure there is for water to move between has to be negligible I'd think. But, I'm no thermal expert either. Perhaps a thermal dabbler?

 

[GaryParr]

Because this is bothering me, I've shot an email off to Hayward asking this very question... is just having water in the niche sufficient such that I can gasket the light. It will be interesting to see if they give a response beyond "modification nulls warranty."

 

[Newdude]

. It will be interesting to see if they give a response beyond "modification nulls warranty."

Gary Gary Gary…….. you know the script. That’s page 7. You have 6 full pages of ‘turn it off and back on again’ like steps to go through first.

 

[Newdude]

I had to cancel my 1 year trial Sirius/XM subscription that was about to renew the other day. The gal on the phone who was in a tropical location claimed to be Karen. Oh !!! Sweetie !!! Just because you’ve heard *that* name in the news over there does not mean people are fond of it. Pick something else next time.

 

[GaryParr]

So, after finally taking my light off for the first time to clean the niche I've discovered a few things.

1. It's surprisingly easier to remove then I thought it would be. One screw.

2. Two screws to remove the trim ring from the light, which I'm glad I did because there was gunk behind it.

3. Why is this not listed as THING ONE TO DO when you start a slam? Holy cow was that nasty back there!

4. There is not a chance of sealing all the gaps in this light short of giving it a plunge in Plasti-Dip. So, yeah... that's a no go.

How often do you guys clean these things?

 

[Newdude]

3. Why is this not listed as THING ONE TO DO when you start a slam? Holy cow was that nasty back there!

Many times it’s not needed. Yours happened to be nasty. Great job taking the chance !!

How often do you guys clean these things?

Usually only when a member can’t pass a SLAM or has it dragging on. I was helping someone yesterday looking for the why it was taking so long and the light was clean. If you don’t, it was. If you do, it isn’t.