Green Algae's behavior at target FC and SLAM?

Jump to latest Follow Reply
pisymbol

pisymbol

0
Gold Supporter
Jul 11, 2014
153
NJ
I'm curious. If you had green algae in the past but don't see any sign of it and are at target FC levels, how does algae grow back?

Even more curious, I realize the SLAM procedure is to kill off any algae in the pool, but if you are at target FC levels, won't that slowly kill the algae off anyway? (or is it that the algae grows faster than the FC particles can kill it)
 
You pretty much got it.

If you have any algae, it can multiply faster than the FC can kill it. Of course depending on how much there is.
As the algae is killed off, FC drops, and before you know it, the FC is below the effective threshold of being buffered by CYA.
So if algae is present, you only need to loose a couple ppm of FC before its ineffective in fighting off the algae.
 
pisymbol said:
I'm curious. If you had green algae in the past but don't see any sign of it and are at target FC levels, how does algae grow back?

Even more curious, I realize the SLAM procedure is to kill off any algae in the pool, but if you are at target FC levels, won't that slowly kill the algae off anyway? (or is it that the algae grows faster than the FC particles can kill it)
Click to expand...
In the case you're presenting, even though the army of algae has been defeated with a SLAM, a few tough diehards stayed behind to wage a guerilla war. They hide in places that are hard to brush and where there is poor water circulation. Algae grows a slimy biofilm that protects it from chlorine, which is why brushing is necessary. If you can't brush it, it can grow behind the shield.

Algae spores are everywhere. How else do you explain some old empty can in the yard full of rainwater turning green? The battle in the pool is just low intensity most of the time.
 
Is this true? When FC drops but CC doesn't rise...

...the FC was removed from the pool due to sunlight and/or evaporation not from killing algae or other organics.

Is this always true? I ask because I have gone two days straight passing the ONCT but now on my third I see that my FC dropped 1.5 ppm but I have had 0 CC since passing my first ONCT (I mean zero zero...). Also note, no signs of anything in the pool (it as clean as it can possibly be, water is almost invisible!).
 
Re: Is this true? When FC drops but CC doesn't rise...

Good to hear your water is clear. Yes, your FC will drop naturally each day based on the amount of sunlight it gets and organic matter it has battled against. Having a CC level of zero is good (ideal in fact) and just means that your water is in a very good place right now. :) We all lose FC each day differently, so over time we learn how much we expect to replenish each day. Does that help you?
 
Re: Is this true? When FC drops but CC doesn't rise...

If you didn't pass the OCLT, you still have something organic causing your chlorine to be consumed. I would proceed to SLAM chlorine level and repeat OCLT.

I had clear water when a small patch of algea appeared on the floor. 4 days into the slam I STILL didn't pass OCLT with clearly sparkly water. Daughter swimming underwater identified for me where she saw "grime" in the tiny cracks in the framing around the shallow steps and deep end swim out. These are cracks where the two frames meet, not flaws. It took getting a hand brush in the pool and sure enough algea was hiding there as well as behind the skimmer box frames. Places my pool brush would never reach.

So, I'd say if you lost 1.5 overnight, you still have something hiding.

That is if I understood your question. Losing 1.5 during daylight would be normal. But bad overnight.
 

Enjoying this content?

Support TFP with a donation.

Give Support
The nooks and crannies in the underside of pool ladders is another favorite place for algae to hide. Normally, these places get little or no circulation (even if you have a return jet pointed directly at the ladder) because of their location. The only real way to clean them out is to scrub them with a small brush then submerge the entire ladder, on its side, in the pool during the SLAM process. Or you could turn it upside down and lean against your fence and pour bleach into them. I did the latter and no longer have algae trying to get a foothold anywhere.
 
pisymbol, something else to consider since I've been thinking about your situation quite a bit from your last post earlier today .... I first read your question in general terms of FC loss during the day, but I see now it appears you are curious about the 1.5 loss overnight, is that correct? After passing 2 days in a row, only to discover a "close" excess loss the 3rd night, it certainly is possible something is trying to return. Good thing is that if your test numbers have been rock-solid for a while, and you do SLAM, it shouldn't take too long to kill any algae. Since you have one of the best kits on the market (TF-100), and I'm assuming you are comfortable using it by now, user error is probably ruled out.

If you would like, along with the advice of the past few comments today, you are certainly welcome to post a full set of numbers for us later this evening. Maybe it will give you some validation before this evening in case you decide to do another OCLT. Just a thought. :)
 
So Texas Splash, since I have a lot of faith in you guys I decided to do the following:

1) Let the FC fall back to normal swim levels (you'll see why in a moment)
2) Enter the pool and do a full interior inspection (something I can't do while in SLAM mode)
3) I noticed deep inside the skimmers, all the way in the corner, there is live green algae (you have no idea how obscure this spot is and it's ONLY because I am a big believer in the TFP methodolgy that I went this far).
4) I cleaned that algae off
5) Continued the inspection and found nothing (in the process I wiped down the entire side walls of the entire pool THREE times)
6) The ladder has been out of the pool, cleaned off and dry for days now (I don't want to introduce any more variables, it's the engineer in me)

I have a humongo party on the 20th (family, friends, the whole nine).

I am going to try to test tonight and see what my overnight chlorine loss is. The quandry I have now is if I start a SLAM tomorrow, I will have to go full stop on Wednesday since I want to the FC to be about 8-10.

My last numbers this morning were:

FC 9 (0 CC and I mean zero)
CYA 45-50
PH 7.2

I brought it up to FC 12 when I cleaned out the algae. I realize I'm not in shock mode but I suppose there is a slim chance that at these FC levels I might pass an ONCT? Right?
 
I just got back from an event with the wife.

12:15AM EST
FC/CC 10.5/0.5

(I did not test CYA, it is too dark, but I will assume my afternoon 45-50 reading is good enough).

The filter will run all night. Pool *looks* clean as a whistle but I brushed a few areas where I have seen sporadic dead algae before for S&G's.

I DO have a pool light but it is enclosed and I have brushed everything on top of it and around it. What else do I need to do? (I have never even thought about removing the top cover to the pool light).

I got to tell ya, no one I know goes through what I'm gong through and I am beginning to think most people just live with algae to some extent (pool folks just clean it off or dump more chemicals to abate the issue temporarily).
 
I'm about to scream....so last night I must have been tired because after testing twice this morning I have:

6:15AM EST:
FC 12.5 / CC 0.5
CYA 45-50
pH 7.5

+2FC which makes no sense to me.

What I don't understand is I added sod-hypo before I left last night around 6:30PM. I had the filter on non-stop and took reading a little past midnight as per comment #15. I would think that would be more than enough time for the chlorine to mix to get an accurate reading. Right? I guess wrong since I'm +2 FC. And yes, I know how to test with the TF-100 (it's not exactly hard). CYA is the same so that's not it. Argh.

I just added some acid to bring it back down to 7.2 (usually takes about a half hour).

Well, the algae is back and with a vengeance, I see it growing out of the lines now and I have now not a clue how this can be possible. Perhaps someone is coming late in the night and dumping highly active green algae spores in my pool. Or maybe it's ancient alients screwing (it's a family website) with me.

One thing, I can not SLAM all friggin summer, both due to the cost and the fact people want to swim in it. I'm at a loss now on what to do.

I am going to bring the pool up to shock, scrub the whole pool down and then figure what to do for the 20th. No one has this problem but me and everyone I talk to that has had some algae goes to the pool store and buys algeacide which is what I don't want to do. What I don't understand is how fast it comes back compared to other folks stories. What the heck am I dong wrong?
 
Did you draw your sample from the same location as all your previous samples? If not, you may have a zone that is not seeing the same circulation as other parts of your pool.

Also during the test, you could have miss counted the reagent drops or, a couple of drops came out at the same time and you did not see all of them. It has happened to me, especially for the first couple of drops, if the reagent is warm. I now give all open reagent bottles a quick squeeze before I start any test to equalize them.

BTW, it is not necessary to test the CYA levels each time you test FC. You're just wasting your reagent. It is not going to change unless you change the water or get a lot of rain.
 
Propbndr said:
Did you draw your sample from the same location as all your previous samples? If not, you may have a zone that is not seeing the same circulation as other parts of your pool.
Click to expand...

Same location.

Also during the test, you could have miss counted the reagent drops or, a couple of drops came out at the same time and you did not see all of them. It has happened to me, especially for the first couple of drops, if the reagent is warm. I now give all open reagent bottles a quick squeeze before I start any test to equalize them.
Click to expand...

Good idea, will do.

BTW, it is not necessary to test the CYA levels each time you test FC. You're just wasting your reagent. It is not going to change unless you change the water or get a lot of rain.
Click to expand...

Yes, I know that. But the sudden increase of FC confuzzled me so I wanted to go back to a steady state.
 

Enjoying this content?

Support TFP with a donation.

Give Support
You must log in or register to reply here.
Thread Status
Hello , This thread has been inactive for over 60 days. New postings here are unlikely to be seen or responded to by other members. For better visibility, consider Starting A New Thread.
Top Bottom
Back
Jump to latest Follow Reply