Algae, but holding chlorine

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Betty99

0
Aug 7, 2013
32
Long Island, NY
FC - 9
PH - 7.6
CYA - 95

A few days ago I started to notice some green stuff in the corners of my crystal clear pool. It was most noticeable near the filter area. I brushed it and today it is back again. I just put in enough bleach to bring me up to a 12 and brushed the corners and sides again. My CC was .5 and I've been losing approximately 3 ppm of chlorine on sunny days. Should I take a wait and see approach or should I just go for the SLAM?

And, yes, I know my CYA is high (former tablet user, just switched to BBB method at end of last season) but the hubby is against draining almost half the pool and refilling. He doesn't want to wait for the water to warm up again. I just keep the FC level toward the high end of what is needed
 
Well, your target FC is 12, so you are well below that. Your minimum FC is 7, and while you are above that on sunny days you can probably drift down to it easily when you say you loose approximately 3 ppm per day. A few days with too little FC allows the algae to get a foothold, then even when you add you never get the FC high enough long enough to eradicate it.

I would ask how you came up with CYA 95? Using a recommended test kit there are only even numbers; 60 - 70 - 80 - 90 - 100. If you are at or near 100, you may need to do a dilution CYA test as that is the upper limit of the test. Mix pool water and tap water then test the mixture.
Here is a great chart by JamesW to identify the multiplier.

Pool water......Tap or distilled water.........Multiply result by

....1...................1................................2
....1...................2................................3
....1...................4................................5

My guess is that your CYA is much higher than you think, thus you have too little FC to combat the algae. But, that is just a guess.
 
CYA I got 95 because my friend couldn't see the dot at 100, but I felt I still could and got to 90, so I split the difference. It was a little iffy.
Didn't realize my target was 12. I always bring it up to there or 12.5 everyday. I've never measured below 7.
With that being said, it still seems like SLAMing is the way to go
 
So, I brought the FC up to my SLAM level. I didn't have any FC loss overnight and no CCs. With FC at 25.5, is it OK to swim? I did a search through the forum and it seems that it is OK, but I just want to verify that that is true for my SLAM level.
 
According to the pool calculator, my shock level is 25 with CYA of 100. Would my shock level be different because I have visible algae?
Another thing may be that it was not algae. I have a couple of large maples hanging over the pool. I do still believe it was algae because, like regular sediment usually does, it did not move when I swept my net over it. I was only able to remove it from the few spots that I found it by brushing. It really was a very small amount that was mostly by the filter inlet and return.
 
Betty99 said:
According to the pool calculator, my shock level is 25 with CYA of 100. Would my shock level be different because I have visible algae?
Another thing may be that it was not algae. I have a couple of large maples hanging over the pool. I do still believe it was algae because, like regular sediment usually does, it did not move when I swept my net over it. I was only able to remove it from the few spots that I found it by brushing. It really was a very small amount that was mostly by the filter inlet and return.
Click to expand...
Are you using the Pool Math link at the top of this page? Both it and the Chlorine/CYA chart show 39 as the shock level for 100 CYA.

But, back to the question at hand. Yes it's safe to swim at 25.5 with CYA 100

Now, last night after the sun was off the pool it was 25.5 and then again this morning? If yes and the water is clear and no CC then I would say it was the shortest SLAM in history.

With 100 CYA target 12 FC and never let it go below 7. I remember these numbers well because I sat at 100 CYA for a while.
 

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I too was surprised, yet very happy, that I passed the OCLT. Just to confirm that I have been measuring correctly, I used the 10mL sample, added the 2 dippers of DPD powder, dissolved it, then I counted 51 drops until the pink color disappeared. I did the exact same thing last night and this morning.
Now, I have to check on that pool math link. Why does the pool calculator tell me 25? Is there something wrong with the calculator?
 
I too was surprised, yet very happy, that I passed the OCLT. Just to confirm that I have been measuring correctly, I used the 10mL sample, added the 2 dippers of DPD powder, dissolved it, then I counted 51 drops until the pink color disappeared. I did the exact same thing last night and this morning.
Now, I have to check on that pool math link. Why does the pool calculator tell me 25? Is there something wrong with the calculator?
Just checked it out. I've been using poolcalculator.com. The only difference I have found is the shock level, which you have pointed out to me. I will be using the PoolMath chart from now on.
With that, since I didn't have any overnight loss, do you think I need to bother bringing FC up to 39 at this point?

- - - Updated - - -

Just did a double check and even with the suggested goal levels set to come from Troublefreepool.com on both the PoolMath and Poolcalulator charts, I get the two different shock goals. Weird
 
Betty, just curious how long you run your pump ??? Crystal clear water with algae forming could mean you are NOT running your pump enough. I just went through a similar scenario and I extended my pump run time as suggested by a good friend. It worked!!! Good luck and enjoy.
 
Just got the stuff to retest my CYA. Apparently, it's at a 60. That's probably why the shock of 25 worked. Guess the refilling and draining that has been going on between the rain and, alternatively, the evaporation, it got there.

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How long do you run it? I alternate between 4 - 8 hours and sometimes even longer if I forget to shut it. I don't put it on a timer because I like to empty the basket when I shut it off and I know I would get lazy about it if it shut off on its own.
 
Still getting the little bits of what I think are algae in the recesses of my pool floor. Also, I used to have that jewel like sparkle to my water and it's kind of gone. My husband thinks I'm crazy and says that the pool is crystal clear, but I know it doesn't look quite the same, although he did comment about the fact that the water had lost some of its softness. Sooooooo confused!
Chemicals seem to be ok.
FC: 9.5
CC: 0
PH: 7.8
ALK: 120

You could see what happened the first time I SLAMed by reading my previous posts on this thread.

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Oh and my CYA is 60
 
I am having the same problem with my water. My husband thinks I am imagining algae since I have spent so much time on here. He thinks the pool looks great and I think it's missing the sparkle I had a couple weeks ago, and what I think is algae he thinks is dirt. I am not losing FC like crazy so I am just checking it twice a day.
 

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