Algae detection?

[midijamm]

My recent shock treatment for recurrence of Algae (May 9) after my first inadequate shock experience was a fantastic success resulting in the cleanest clearest pool I have ever seen.

Did the OCLT as outlined and all was good.

Since then I got the CYA up to a bit over 30

Present tests are:

FC 4
CC 0
PH 7.2
TA 70
CH 180
CYA 34

BUT

A few days ago I took out the trichlor Puck cause the FC was getting high and forgot to put it back in for a day. Big rain came and FC got down to 2. Greenish Yellow dust started appearing on floor. I brushed the whole thing and backwashed the filter…then checked the CC again to see if that changed it (stirring up the dust) but it still read 0.

My Question is: Is there a way to test and determine if this is algae or dirt/dust from roof screen (It is a screened Pool). Like an OCLT test to indicate that there is Algae eating up the Chlorine? I realize that it will become obvious in a day or two if it is back again but if I can determine if it is algae I can start the shock now and get done sooner. It was darker and thicker on the deep end which is the opposite of what I read about Mustard Algae formation symptoms.

TIA Pool Gurus!

 

[Azgirl71]

nevermind. I see your CC IS 0. I am sure someone will be along with an answer. I would say lots of brushingand vacuuming and bring water up to SLAM lever for 24 hours then run a OLCT.

 

[JasonLion]

This is a perfect situation for using the OCLT. If there is algae in the pool it should show up on the test.

CC almost always stays at zero when you have algae, so that is not a useful indicator.

 

[midijamm]

OCLT!

Right On

Will do!

 

[Jeffc2112]

This is a perfect situation for using the OCLT. If there is algae in the pool it should show up on the test.

CC almost always stays at zero when you have algae, so that is not a useful indicator.

Hi Jason, was just following along this thread and was curious why you say CC almost always stays at zero with algae, isn't that one of the conditions we're testing for when SLAM'ing? My thought was the presence of CC's meant you were killing algae or something, so it should show up as greater than zero, no?

Thanks, Jeff

 

[jblizzle]

CC are broken down by the FC and the sun, so you may never actually see high levels. This is why the low CC is not the only criteria and there are 3 separate things that you must pass to know you are down with a SLAM.

 

[midijamm]

Strangeness…

OCLT shows no loss…
in fact if anything it show FC gain!

I know that sounds like poor testing but I was especially careful even to the point of using 25ML of water for the FC test and scraping the DPD spoon with a straight edge for accuracy and last night it took 19 drops to clear the water then 20 drops this AM.

I realize that is probably an irrelevant difference but how can you lose 0 PPM overnight?

 

[jblizzle]

You can not use too much powder, but too little can cause problems.

 

[midijamm]

You can not use too much powder, but too little can cause problems.

Thanks for that.
Education continues and is cumulative (Thank God, I don't have to remain a dummy) :O)

So perhaps my testing was faulted? .05 is my usual overnight loss

 

[Richard320]

One drop is well within the tolerance of the test. You didn't blow it.

 

[midijamm]

Twilight zone…..

Yesterday multiple tests showed 4.0 FC

OCLT was 4 and 4+

now at 4 PM and after a sunny day in the keys and NO CLORINE ADDITION it is 5.0

6:15 PM down to 4+

 

[jblizzle]

What does 4+ mean?

Clearly this is not possible without adding chlorine.

 

[Azgirl71]

I agree with Jason.

 

[midijamm]

Well that is certainly the answer I expected.
That is why I think I am in the twilight zone

4+ means with a 10cc sample it turned clear with 8 drops but within 30 seconds it got a very pale pink hue so it's 4.5 or less?

 

[jblizzle]

Once it is clear, you are done and should then proceed to the CC portion of the test. It is normal for the sample to turn back to pink after some time.

 

[midijamm]

Ok but I am still left with the ridiculous situation that in 24 hours I am reading 0 chlorine loss with no Chlorine addition.

I did put in 3 cups of acid about 11 AM to move the PH down a little.

That is the only thing that went in the pool since yesterday

 

[jblizzle]

Has to be testing error or somehow chlorine was added to the pool or your water is not well circulated.

If you used 25ml of water and only 1 level scoop of powder, that may not have been enough powder.

FYI, the OCLT should typically be performed at FC levels closer to shock level than maintenance level.

 

[midijamm]

Oh well I think I better shock cause the color is wrong, it is cloudy still after running the pump all day and there has to be something wrong.

Just when I thought I had a handle on all this some inexplicable mystery happens.

Should I go to Mustard shock level or regular….best guess advice :O)

 

[jblizzle]

Always regular shock level.

 

[midijamm]

I have been SLAMming for 5 days now. The overnight FC loss has been 0 since the beginning as has the CC but I keep going because of the Green dust

Every morning the pool is clear but when I brush there is green dust on the bottom and sides. It is decreasing but the green color makes me think there is still living algae.

The last (and first) time I SLAMmed it I didn't have a DPD test kit and used WAY too much Chlorine and all the dust turned White, almost Clear in fact.

I think there is something evil in this pool like black Algae?

The skimmer leaks so I lower the water below it to save on leakage and the exposed tiles have black areas in the grout.

Any one gotta thought about this?

(Am using liquid Chlorine and keeping it around 16 PPM w 40 CYA…PH was 7.2 at start)