How to handle algae in pool light during SLAM?

[BlueKimba]

I am preparing to SLAM my pool for the first time, due to (hopefully, green) algae that's been growing on surfaces for a couple of months now. The water is (and has been) clear enough during our recent summer, possibly due to the benefits of the UV light that is installed in my system. I was also using low doses of a Polyquat 60 algaecide all summer, which I hoped would give me sufficient protection against algae on top of 1ppm FC levels.

I think what went wrong is that my FC levels dropped too low on multiple occasions during the summer. I use a semi-automatic (semi-manual?) liquid chlorine feeder, which requires me to adjust the running time to get the "right" level of chlorine. The aim was to be at about 1 to 2 ppm, supported by the UV light, because chlorine is irritating to my eyes and lips. This worked fine last year. But something was causing the FC to drop lower this summer, and I was too slow to get onto it. (I'm not sure if the chlorinator is feeding more slowly, or the quality of the liquid chlorine has dropped, or something was consuming more of it.)

A few days ago, I did the overnight FC test using a FAS-DPD kit, and it is losing well under 1ppm overnight, but there is undeniably algae growth on surfaces, especially in nooks and crannies.

I have read up about the SLAM process and am preparing to do it, but am not sure how to handle the algae that got into the retro-style pool light, which was fitted two years ago by the guy who replastered the pool (see photo). Is that cover not meant to be sealed? Can that be opened up (after disconnecting the 12V), or do I need to do a partial drain of the pool to access it?

Any help is appreciated.

 

[proavia]

What test kit are you using? Add your test kit to your signature.
Since you're down under, the Clear Choice Labs kit is probably the only one with the necessary reagents to do a proper SLAM Process.

Post a full set of current test results from one of the recommended test kits.
FC
CC
pH
TA
CH
CYA
Water temperature

Chances are it is the byproducts of chlorine doing its job that is irritating your lips and eyes.
That big orange ball in the sky provides more UV than most any addon UV system for pools.

 

[BlueKimba]

Thanks for your comments.

Hmmm, I recently bought (just) the FC/CC test kit from Clear Choice Labs. The other results below are from pool shop testing, so might not be as accurate. FC was higher yesterday, but I let it drop back a bit today (because I wanted to swim .

FC 2
CC 0
pH 7.3
TA 90
CH 290
CYA 36
Water temperature 25 deg C

Do I need the full kit from Clear Choice Labs to do a SLAM? I am close to buying one, in any case.

Here's a better photo of the light, taken from directly above, and I remembered that the light is (probably) this one: RETRO GKRX — Spa Electrics. The linked YouTube video shows that the cover will come out after removing the single screw at the top. It didn't occur to me that it might be that simple, But is it normal for algae to get in under the glass?

I'm a little worried that I might have a mustard algae problem, because of some odd things I noticed during the summer. At times, the FC definitely went too low (face palm).

 

[TinFoilHat]

It's very common for algae to get into everything, including the light. You need to open and expose your light, floor drain, skimmer, skimmer weir, pool return nozzles, any ladders, and clean them inside and out with chlorine to kill the algae that's hidden.

 

[Mdragger88]

The link to the light isn’t working for me but most lights are designed to be kept cool by the water in the niche.
If there’s a gasket between the cover and fixture you may need to replace it after giving everything a good scrub before replacing it.
It kinda looks like there may be some rust going on also.
Unfortunately if you don’t follow the appropriate FC/CYA Levels you’ll likely always be dealing with algae and possibly other irritating nasties common in an undersanitized pool. Whether you use uv or not.
Your trusty uv apparatus can only affect what it comes into direct contact with and provides zero residual sanitation in the body of the pool. That’s if it’s operating optimally. There’s not much way to tell when the device “loses its magic” unless it completely goes out.
The majority of issues that people attribute to /blame on chlorine have to do with improper balance of multiple parameters & ironically enough that “chlorine smell” & eyes burning etc. can be attributed to inadequate fc levels in relation to cya which allows for persistent irritating cc’s.
A clear pool doesn’t automatically equal a sanitary one. Algae is just the canary in the coal mine. If its growing other things are too but its absence doesn’t mean you’re in the “clear”. The only way to be reasonably certain is confirmation of adequate sanitizer levels.

 

[Bperry]

I'm a little worried that I might have a mustard algae problem, because of some odd things I noticed during the summer. At times, the FC definitely went too low (face palm).

Almost certain you have plain old regular algae cause by inadequate chlorine. The sun (and your UV) system degrade chlorine anywhere from 1-5ppm each day. If you start the day at only 1-2ppm you will continue to have the same problems trying to maintain abnormally low chlorine levels.

It was hinted at above but most every person who is sensitive to chlorine is actually just sensitive to the by products of chlorine breaking down things like algae. It’ll sound counter-intuitive but the solution to that is increasing the chlorine levels so that organic matter can’t grow and therefore can’t be oxidized by chlorine.

This is all assuming you are maintaining the correct FC/CYA ratio in the water. Here’s the chart:

The Free Chlorine and Cyanuric Acid Relationship

Managing your cyanuric acid and Free Chlorine levels is key to stabilizing your pool. Learn how these two items affect each other.

www.troublefreepool.com

Too low of stabilizer level (CYA) with very high FC can also be irritating. If you keeping those two things in range you’ll likely have a much easier time with the pool in both comfort and no algae.

 

[Newdude]

At times, the FC definitely went too low (face palm).

* all the time.

 

[BlueKimba]

Thanks for all the replies.

I have a curved profile where the floor meets the wall, and there is a build up of what looked like grey dirt, but now I see signs of greenish algae growth there. I initially blamed the dirt on my first attempt at using a cheap robot (Aiper Scuba S1), which seemed to have trouble getting to the curved edges, unlike my older suction cleaner.

There are some unused eyeball jets (for a solar heating system that the previous owners never installed), and I found plenty of green algae in there after I pulled them out.

Maybe I need to install an outside shower, so that I can easily shower off as soon as I get out of the pool...

In case that link to the light is generally unavailable outside Australia, this 3 minute YouTube video shows how to install it, so I guess it's not too hard to remove it...

.

 

[Newdude]

Maybe I need to install an outside shower, so that I can easily shower off as soon as I get out of the pool...

The 'chlorine smell' and feel is from having too low FC. If you can smell or feel it, it is reacting with things growing in the water. The fact that they were growing in the first place means the FC was too low.

TFP pools have no smell and I often use mine instead of a shower. I never liked other peoples pools and always raced to take a shower. I've since learned it wasn't the pool, but that the pool was gross with improper chemistry.

 

[BlueKimba]

The 'chlorine smell' and feel is from having too low FC. If you can smell or feel it, it is reacting with things growing in the water. The fact that they were growing in the first place means the FC was too low.

TFP pools have no smell and I often use mine instead of a shower. I never liked other peoples pools and always raced to take a shower. I've since learned it wasn't the pool, but that the pool was gross with bad chemistry.

Interesting.

What I tend to notice (and I am sensitive) is that it feels fine at first on leaving the pool, but I notice it later on my skin, with irritated eyes. This is especially so in public pools, even when I shower after swimming. I always suspected that some of the chlorine sits and reacts with bacteria on my skin to form CC, but you maybe that's wrong...

 

[Bperry]

Interesting.

What I tend to notice (and I am sensitive) is that it feels fine at first on leaving the pool, but I notice it later on my skin, with irritated eyes. This is especially so in public pools, even when I shower after swimming. I always suspected that some of the chlorine sits and reacts with bacteria on my skin to form CC, but you maybe that's wrong...

Public pools have some of the worst sanitation if you read through some of the threads on them here. I’ve had a similar experience a few times. Don’t judge anything about chlorine based on a public pool experience.

 

[Newdude]

Some are truly sensitive, but many just think they are because pools are often mismanaged, public or private.

At the very least in your pool, your FC was low. New chlorine added got right to work and you got the smells/feel. At the next dose, FC was low again and it was an endless cycle.

 

[Mdragger88]

From watching the video It looks like there’s water intrusion where there should not be in the light. The website says they all have 3yr warranties so I would submit a claim while you still can

 

[BlueKimba]

It turns out that these Spa Electric pool lights have a plastic cover over the lens, and they are notorious for developing algae under the plastic cover. It's easy to remove it for cleaning with a sharp-edged screwdriver, which I have now done. Thank you to this man for another one of those helpful videos (

).

Once I've completed the SLAM and (hopefully) got rid of my algae, I have all winter to think about how to handle the pool chemistry next summer. The swimming season is almost finished here, given that it's an unheated pool.

 

[Mdragger88]

Great news about the light!
Have a look for after your slam is complete

Closing an In Ground Pool

Winterizing a pool is essential for keeping your in-ground pool protected during cold-weather months. This Pool Repair guide will show you how to do it.

www.troublefreepool.com

 

[BlueKimba]

The winters in Perth are very mild, so it isn't necessary to close the pool. Winter seems to be relatively easy, even for a first-time pool owner like me.

 

[Mdragger88]

We have a guide for that too!

Preparing Pool for Cooler Months - Further Reading

www.troublefreepool.com