I have high chlorine levels but algea keeps coming back

[filmdog]

A few weeks ago we came back from vacation to find a family of ducks in the pool. We got them safely relocated, but were left with algae on the walls. I've shocked, brushed, backwashed and vacuumed a few times, but it still keeps coming back.

Currently I've got very high Free Chlorine of 17.25 ppm (due to three shocks in the last two weeks) but algea still grows. (Shouldn't that chlorine level prevent further growth?)

My pool store keeps advising algaecide, but everything I hear saiys it's bad for the filter.

Should I try to shock harder? Do I have to deal with the CYA? (I'd rather not drain the pool.) WILL algeacide help?

I'm at a loss for what to try next. Any advice is appreciated.

Here are test results (from pool store - Anthony & Sylvan, which uses electronic testing):

FC: 17.25 ppm
CC: 0 ppm
pH: 7.6
TA: 74 ppm (have been advised to raise it
CH: 200 ppm
CYA: 100 ppm

 

[FamilyGuy]

If you want an easy to maintain crystal clear pool you need to invest in a quality fas/dpd test kit. Poolstores are in buisness to make money not test your water accurately for free.

 

[pwrstrk]

Read the SLAM process in pool school. SLAM stands for shock level and maintain. You also need a good test kit to SLAM.

The reason it keeps coming back is your not following thru with the SLAM.


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[filmdog]

Thanks, I just ordered a TF-100 test kit. In the meantime, I read the SLAM instructions, and it seems to say that I need to get the FC higher than the current 17 ppm. But if I add shock won't that raise the CYA?

 

[pwrstrk]

We like to use liquid chlorine for the SLAM. Bleach is the way to go.

Good job on getting the test kit. It's a must have. You need that so you know where your levels are for the SLAM.


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[FamilyGuy]

Unless your cya is low or you plan to drain and refill the tabs are not a good idea. Most of us use simple unscented laundry bleach

 

[pwrstrk]

The problem with the test results you have is we can't trust them. Espically the cya test.


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[woodyp]

It is highly likely that your CYA level is well over 100. It makes fixing problems with algae all that much harder due to FC requirements at those levels. Algaecide will NOT help. You'll be better off draining it by at least a third before your kit comes in.

 

[filmdog]

Ugh. I will likely have to drain by 1/3 or so to reduce the CYA. It was 90 ppm last week, prior to a shock treat with Di-Scholor Super Pool Treat. But now I understand that the shock treatment added CYA.

On the liquid bleach, can I just use Clorox? And if so, how do I know how much to use?

Thanks.

 

[mk1]

here...

http://www.poolcalculator.com/

 

[pwrstrk]

Get the bleach at Walmart. Their brand. It's cheaper there. Just plain non scented bleach.


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[JohnN]

The problem is that your CYA may be higher than 100, which would mean you need to drain more than 1/3. If your CYA is 150, you will need to drain 2/3. You would probably be safe to drain 1/3 now, but wait until you get your kit to go any further.

 

[filmdog]

Thanks everyone.