Something in pool, not sure if it is algae

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dknyli

0
May 12, 2014
14
New York, NY
My pool was opened last week by a company I hadn't used before. It's always dirty when it's first opened but clears up in a few days. I put the bot in to clean it and ran it several times. Once all the big stuff was gone, there was still some fine black debris in the places where the walls meet the bottom. I decided to brush it all to the bottom and then vacuum it manually.

By this time (yesterday), the water was sparkling clear and the pool looked great except for that gunk in the corners. But when I started to brush, I realized it was dirtier than it looked. Each push of the brush brought up clouds of fine black debris and once areas are brushed clean, it's obvious how dull the liner looks in the rest of the pool. After vacuuming, the pool looked great but later on I realized I missed a few spots.

Today, it's as if I never vacuumed it. Is this algae? It's not green, it's black. When we've had green algae in the past upon opening the pool, it always goes away with some brushing and a few days of running the filter.

I don't have a good test kit although I did order one. The cheapo test strips I have say the pool chemistry is perfect!


I don't know how to make a signature so here are my pool stats:

In-ground, vinyl liner, 16,000 gallons, Haywood Pump, DE filter, Polaris automatic cleaner

Thanks!

dknyli
 
Welcome to TFP :)

To get the best advice here it is recommended that you get a good test kit. Do you have any results of testing you can post? (Pool store results are suspect but better than nothing)

Have you read the ABC' s of pool water chemistry in pool school? That is a good start. Click on "Pool School" in the upper right hand of the page.

It seems like a simple question that you ask, but the answer is dependent on your water chemistry. I'm guessing algae.
 
Welcome!

dknyli said:
The cheapo test strips I have say the pool chemistry is perfect!
Click to expand...
There's two things wrong with that statement. First, you probably know how we feel about strips. The second is that any snapshot of your test results might say that the chemistry is perfect right now. But if you test an hour later and all of your FC is gone, it means that there is clearly something living in your pool.

I also would guess algae, but repeated reliable testing is the only way to get a good diagnosis. Glad to hear you got your test kit on order. While you're waiting on the delivery, read as much of Pool School as you can handle.
 
Okay, thanks. I figured algae, too, and I put some bleach in the pool (two separate applications) but reading the info. here I'm guessing what I did wasn't enough. I'm freaking out a little bit because I'm working tomorrow and will have a very small window between 4 and 6 pm to deal with this and then back to work for several hours. Wednesday will be a little bit better in terms of time and then I have two days off .... I'm afraid my pool will be a swamp by then! Unfortunately there is no time for me to go to the pool store so I'm really hoping the test kit shows up stat!

How do I make a signature?


dknyli

16000 gallon inground pool, vinyl liner, DE filter, Haywood pump, Polaris automatic pool cleaner
 
dknyli said:
Okay, thanks. I figured algae, too, and I put some bleach in the pool (two separate applications) but reading the info. here I'm guessing what I did wasn't enough. I'm freaking out a little bit because I'm working tomorrow and will have a very small window between 4 and 6 pm to deal with this and then back to work for several hours. Wednesday will be a little bit better in terms of time and then I have two days off .... I'm afraid my pool will be a swamp by then! Unfortunately there is no time for me to go to the pool store so I'm really hoping the test kit shows up stat!

How do I make a signature?


dknyli

16000 gallon inground pool, vinyl liner, DE filter, Haywood pump, Polaris automatic pool cleaner
Click to expand...
Welcome! :wave:

To change your profile and/or signature, select "Settings" (top right under Pool School button). Scroll down (left side) to "My Settings" & select Edit Profile or Edit Signature.
 
If your pool is clear, it may not be algae (notice I said may not). This same issue happens to me every year when I open up. Because I have a loop loc cover, lots of stuff (dirt, dust, leaves, debris) gets in my pool over the winter. My pool usually opens up crystal clear, but it takes me several days of filtering (DE filter) and constant brushing to eventually get all the dirt, dust, to be filtered out. I see gradual improvement each day until it finally disappears. Keep brushing and filtering it.

The only way you will know for sure what it is, is to to the overnight loss test. If you are holding your FC levels overnight, it's probably dirt.
 
duraleigh said:
+1 what run53 said.
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Ok, I got my testing kit yesterday and just finished testing.

FC = 15
CC = 2.5
PH = 7.4
TA = 40
CH = 100
CYA = 100+

Now what does it all mean? Is it possible I over-chlorinated thinking I had algae and maybe it's not algae? If it's just dirt, we've never had this level of dirt before. I've run the bot several times and vaccuumed manually once in addition to brushing just about every day, sometimes more than once a day. Maybe it's pollen? There's a ton of pollen in the air. The other day I went outside and it appeared to be raining pollen.

If I did overchlorinate, then I need to let some water out and replace with new to reduce the FC and the CYA? And then do something about the PH but not sure yet what that is....must go back and read some more.

I appreciate the responses so far and as soon as I have a moment I will make a signature.




Pool is IG, vinyl liner, 16,000 gal., DE filter, Haywood Pump, Polaris automatic pool cleaner
 
Very revealing. It is REALLY helpful when we get test results.

1. Drain your pool in increments of 1/3 to 1/2 and stop when your CYA tests around 50 ppm. Should be two or three drain/refill cycles but could be more.

2.. Reading assignment. Read "The ABC's of Pool Water Chemistry" up in Pool School. That'll give you some better understanding of what we teach and the guidelines you are looking for.

3. Prepare to SLAM your pool after the CYA is 50 ppm. read "SLAM" in the "How To" section up in Pool School but don't start that until you get your CYA around 50 or so.
 

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Update: did the pool SLAM yesterday after draining and refilling several cycles to get CYA down. I also backwashed the filter.

Before SLAM, FC was 7.5, CC was ?? (testing sample didn't turn pink), ph was 7.4, CYA was just under 60.

Using pool math, I put in the bleach and then left the filter running overnight. Just tested now and FC is 22, CC sample again did not turn pink, ph still around 7.4 and CYA is slightly under 60. I think my mistake was that I should have tested about an hour after SLAMing so I could compare to today. But there is still stuff in the pool that is not obvious (water is clear and sparkling) until I brush. So I should SLAM again, correct?
 
Just a quick clarification -- "shocking" is a one-time addition which may or may not kill everything, while SLAM (shock level and MAINTAIN) refers to keeping the FC above a certain level through frequent tests & additions long enough to kill everything for sure.

So you only SLAM once, but it might take several days ;)
 
To illustrate what Bridgman said:

ShockSLAM
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The SLAM should not need to be repeated, but it's pretty dull just watching it get blue and stay there.
 
run53 said:
Depends,

What was your overnight FC loss?
Click to expand...

I made the rookie mistake of not testing an hour after adding the bleach. According to pool math, I needed to add enough bleach to get it to 26. It was 22 yesterday. I backwashed because the filter was sluggish, did a lot of cleaning (brushing and vacuuming) and added more bleach, again shooting for FC of 26. An hour later it was 24.5. Today it is 22. There is definitely no CC so I guess that's progress. However there are still clouds of debris when I brush. Since I'm not done with the SLAMing until pool is clear, I will add more bleach now, wait an hour and then add more. Hopefully this will do the trick.
 
dknyli said:
I made the rookie mistake of not testing an hour after adding the bleach. According to pool math, I needed to add enough bleach to get it to 26. It was 22 yesterday. I backwashed because the filter was sluggish, did a lot of cleaning (brushing and vacuuming) and added more bleach, again shooting for FC of 26. An hour later it was 24.5. Today it is 22. There is definitely no CC so I guess that's progress. However there are still clouds of debris when I brush. Since I'm not done with the SLAMing until pool is clear, I will add more bleach now, wait an hour and then add more. Hopefully this will do the trick.
Click to expand...

Since you already passed the clarity and CC tests, you could be done SLAMing if you can pass the overnight FC loss test. The fact that some dust is still there does not necessarily mean you have algae. It could be just that.....Dust or dirt. I run into this every year after opening the pool. Fine dust/dirt particles that have gotten under my cover over winter settle to the bottom for about 10 days after opening. I have to brush couple times a day and finally after 10 days to 2 weeks, it all gets filtered out.

Like I said before, the only way to know for sure if you are done SLAMing is to finish the 3rd test (Overnight FC Loss Test).
 
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