slightly cloudy water

[run53]

First, my numbers:

TC=6.5
FC=6.5
CYA=60
TA=75
pH=7.6
CH=180

OCLT - consistently 0.5 or less (occasionally 1.0) - measured over 2 week period

I've been battling this all season. When I opened in May, I shocked the pool and noticed that once the FC got to around 5.0, there would be a slight cloudiness to the water, I mean really slight to the point where I question if it is really cloudy. But I know what it looks like when it sparkles and that's my reference point.So, then I shock it and within hours, it sparkles.

So, it's driving me crazy......I would think the a 5.0 FC should be fine for my pool (SWG at 60 CYA). But for some reason, once it hits that level, I start to notice this slight cloudiness.

So that's where I am now.....I will shock this morning and I'm sure it will be crystal clear by later this afternoon. But any ideas of why this is happening at what I would call a reasonable FC level? Especially since I continue to pass the OCLT?

 

[Texas Splash]

Run53, your CYA is a bit low for an SWG. Ideal is 70-80, and depending on your location (heat & sun) your water may be struggling to keep pace. And when you say "shock", what are you doing this with? TFP does not shock, we "SLAM" for a consistent length of time. I suspect you will need to SLAM (link below) to clear your cloudy water. After that, increase your CYA to at least 70 to help protect the FC your SWG is generating.

 

[run53]

Run53, your CYA is a bit low for an SWG. Ideal is 70-80, and depending on your location (heat & sun) your water may be struggling to keep pace. And when you say "shock", what are you doing this with? TFP does not shock, we "SLAM" for a consistent length of time. I suspect you will need to SLAM (link below) to clear your cloudy water. After that, increase your CYA to at least 70 to help protect the FC your SWG is generating.

I am going to get the CYA up to 70 but only after I finish the current SLAM process.

By shock, I mean bring to shock level with bleach (about 20 ppm) and maintain it there until OCLT less than 0.5, clear water and CC less than 0.5. Which all occur on the same day (or overnight). Then the FC slowly comes down until it gets to my target (I like to keep between 6-8). Even so, at 5ppm this slight cloudiness always appears. Everything I read here says that 5ppm should be ok given my CYA. I've been monitoring my FC twice a day (sometimes 3) to make sure it never goes below 5ppm. So, this whole thing is really puzzling me. I can see if I let it go to 2ppm or maybe even 3ppm, but 5?

At times, it does seem my SWG is not keeping up. I run it 12 hours a day at 65%. Maybe I need to run it at 80%? But still, why do I lose the crystal clarity at 5ppm? Doesn't seem right for my numbers.

 

[Pool Tool]

Annoying situation definitely. It is possible that you have continuous algae growth that is requiring your SWG to run longer or it is starting to fail. I would definitely make sure to open any light niches and remove and scrub the stairs/ladders. They may be holding some residual algae that is protected during your short shock periods. One option is to remain at SLAM levels for an extra day and/or follow the mustard algae method just to be certain you have it beat. Then let it fall to normal levels.

Sorry if this is all stuff you have heard/read before. Good luck.

 

[Patrick_B]

I'm not surprised, and there is likely more than one thing in play. Imimagine that your FC dips lower more often than you think. If I were betting on the main cause, that would be it, but other factors like bather load, and possibly nutrient levels for Algae come into the picture as well.

 

[run53]

I imagine that your FC dips lower more often than you think. If I were betting on the main cause, that would be it,

Hmmm...interesting. With an SWG, I would think that it's fairy constant. So I've been monitoring mornings and evenings, before the pump turns on. At these times, FC is never below 5ppm. Once the pump kicks on, it is consistently generating chlorine, so even if it does go down, I would think only a bit.

I guess my question really is....what should my realistic target be for FC with an CYA of 60. I've been targeting 6-8 but as I mentioned, sometimes it goes to 5 and that's where I see the slightest cloudiness (still clear but not sparkling). According to the charts, I should be able to go down to 3ppm with the SWG.

Thinking I will follow the advice of continued slam process for a few days, even when OCLT, Clarity and CC's pass the test. Also, no ladders, lights or crevices where algae can hide. The only place I can think of is the returns where the water directors screw in. I will brush those down.

Thanks for all the dialogue, I think it helps me think through this.

 

[run53]

I would definitely make sure to open any light niches and remove and scrub the stairs/ladders. They may be holding some residual algae that is protected during your short shock periods.

Great thought!

So even tho I don't have any step/ladders/lights, I pulled off my skimmer plates and return directors. Guess what i found? Green stuff in the crevices. So I cleaned them all out with a tooth brush and sprayed bleach in the cracks.

Now I'm curious....how do these areas escape the multiple slamming treatment anyways?

 

[kimkats]

WOW yet another place for the nasty algae to hide! Man that stuff is tricky!

Good job finding your "problem" area.

Now lets see what happens now that you have found and cleaned the hiding place.

I would make a note to self to take off and clean these areas about twice a month or more as you pool tells you.

Kim

 

[Pool Tool]

Now I'm curious....how do these areas escape the multiple slamming treatment anyways?

You know what they say about curiosity right... just kitten. Get it? Ok, pretty bad joke.

I dont know really. I have read that algae forms defensive shell protecting itself or that the water immediately around the algae is at a lower FC once it oxidizes some of the spot algae then can't kill the rest. I think this is why you'll hear a lot of the brush often, keep pump circulating and maintain slam level comments.

Even though I am not totally certain here is my approach. The slam levels (with sufficient time) will kill all the algae period. The suggested FC min and max levels are guidelines to maintain algae free water. These levels though, in the right conditions, may not completely win the battle against established algae. Once that algae that snuck through the SLAM starts to grow it will eventually outpace the ability of the FC to kill it. That's why the water clouds first, then starts to show green on the sides and/or in the shade and if let untreated will turn a decent looking pool totally green very quickly. It also seems that's why catching it early considerably decreases the duration required to SLAM.

It is possible that you and I (last year) battled recurring algae because just enough algae survived initial SLAMs to multiply and cause issues again. Now that you found, exposed and killed that last vestige of algae you can have a TFP.