An algae conundrum

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D

ddas

0
May 21, 2013
131
Los Angeles, CA
For the past couple of months I've had a recurrent algae problem. The algae is orange-brown, so I assume (?) it's probably mustard algae. I use the TFP algae treatment to the T, then find a couple of weeks later that I notice it growing back. This has happened 2-3x in a row now. I keep thinking: "I must have missed something -- maybe I didn't scrub enough on the tile or in the skimmer or somewhere else..."

So I just raised the FC level to about 35. (My CYA is 50.) I'm brushing the pool daily.

Today I noticed something interesting. My pool has an underwater light (see http://imgur.com/a/RQ6fV). It's held in place by just one screw (at the top) -- don't know where the bottom screw ever went. Well, I noticed some algae around the outside ring of the light...and...(drum roll)...I noticed that the light was slightly rotated and not centered, so there's a crack of an opening, allowing water to enter the cavity behind the light.

What are the odds that I've got an algae outbreak behind the light?

I can't get to the light without diving in the pool.

Now, this gets a little tricky from here. I'm in SoCal, but the temps are now cold at night -- my pool isn't heated, and the water temperature is in the 60's. It would be uncomfortable for me to get in the pool, unscrew the light, bring it above water, and thoroughly scrub out the cavity. Not impossible, but uncomfortable. (Usually my family won't swim in the pool if it's below 80!) Do any of you swim in the 60's?

So what do I do? It's now approaching winter, and the earliest we might have swimmable temperatures will be April. But I'm thinking it's not wise to leave a major algae bloom behind that light for six months...

Any thoughts?
 
That algae is a tricky thing for sure! It has found a good hiding place behind that light and is having a party!

Could you lay down and reach the light that way? With only your arms and hands in the burrrrr water?

Kim:kim:
 
Yeah, probably/possibly. If I did this, I could probably reach the screw, unscrew it, and bring the light above the surface.

However, I couldn't clean out the area much. I really don't have a good picture of how much scrubbing is necessary, or just upping the chlorine would be enough.

I also couldn't put the light back without jumping in. Theoretically I guess I could live with the light being out for the next six months. It'd be ugly (because the cable would be connected from the cavity), but I can live with it.

Thoughts?
 
With the light out the FC in the water has a better chance of getting into the light housing but you could just wait until April if you want. I don't want it to get any worse so that is why I suggested taking the light out.

Kim:kim:
 
I have done the "bend over and remove the light thing" from the deck several times. I also reinstalled them (I have two lights) from the deck ONCE. It was very difficult, but I did it. I cleaned it with a brand new toilet brush. I knew I wasn't cleaning it perfectly, but felt it was better than nothing.

Now I clean my lights at least twice a year when the water is warm.
 
(OP here.)

Hehe. Thanks for all the input.

I did a quick search on algae growing in colder water, and it looks like it does still grow, but at much slower rates.

Which makes my question even more tricky. Do I:

Door #1: hope algae is not behind the light, finish my SLAM, brush consistently, keep the FC level a little higher than usual all winter (I don't mind doing that), and hope I don't see anything too bad? The downside: if I see significantly more algae in a month, the pool temp will then be in the 50's and there's no way I'm diving into 50° water.

Door #2: brave it, jump in the 60°*pool now, remove the light, clean behind the cavity as thoroughly as I can?

Door #3: somehow see if I can get that screw loose (difficult, because of my waterfall/rocks right above the light), get the light above the surface, then leave the light above the surface all winter long (ugly)? I still won't be able to really get into th cavity to brush/scrub/clean it, but at least it'll be exposed to plenty of chlorine which should inhibit its growth if it's there.

No great solutions...I'm torn. Thanks for all the input though!!
 
Door #4, do you have a friend with a wetsuit willing to go in or you could borrow the wetsuit off of?

Door #5, put some straight bleach in a squishy bottle, like a water or sauce bottle and try and squeeze the bleach in behind the light

Personally I would take door 2 and 3. Remove light deckside, scrub with a brush as much as possible deckside, then jump in to finish the cleaning and reinstall the light, with the priviso that there was a hot shower waiting and ready as soon as I finished. I would do this because it would worry me all winter if I did not (I am a worry wart tho) and thinking that once your water hits 60ish degrees the algae may start growing rapidly and you have a horrible green spring pool opening
 

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1. The light ring is only held by one screw....there is no other.

2. Take some clorox in a turkey baster and squirt it behind the light and into the niche.

3. The algae you see is not being generated by algae behind the light. It is almost always because of low chlorine in general.....can you post current test results?
 
Current readings:

FC = 35 (because I just started a SLAM and I'm erring on the higher side because I want it gone!)
PH = 7.0 (lowered a little extra low before starting the SLAM)
TA = 80
CYA = 50

I really appreciate everyone's input.

@Duraleigh -- any reason you so strongly suspect I don't have an algae concern behind the light? I'm happy to do the turkey baster thing...just trying to understand more about how algae behaves and how to get my pool to healthy.
 
Algae behind the light niche is often used a a crutch for inadequate FC in the pool water. There is maybe only a gallon or 2 of water in the niche so the volume is not very significant in a 20,000 pool. Also, algae needs sunlight to grow so the niche is not a spot it relishes. I think folks often get water mold in a niche (where it likes to hide) and mistake it for algae. I just don't think the light niches provide enough opportunity to harbor an algae bloom. That SUPER-blast of chlorine with a baster (maybe 3-4 times each season) will likely kill everything back there including water mold.

Over the years, we have thousands of pools that stay pristine simply by having adequate chlorine and practicing the brushing, vacuuming protocols established on this forum..

A set of inserted steps is a more likely scenario for algae hiding. The volume is wa-a-ay bigger and more light often gets in. I think I can go along with algae hiding under steps but I don't think the niches provide enough opportunity.
 
Thank you for that. Very good to know, and very good point about the sunlight. I will force some chlorine back there for sure.

For anyone following this thread with interest, I've decided not to remove the pool light. I'm SLAMming the pool, brushing it daily, vacuuming it every few days, and the temps are going down. I'm hoping this will be enough.

Worst case, if the algae comes back, I might later decide to remove the pool light, which I can probably do from the surface with difficulty, and if it comes to that, I'll just leave the light out of the pool all winter. But given the info above, it seems unlikely I'll have to do this.
 
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