Results confusing after shock.

[Whatrymes]

Hey, shocked the pool due to some visible green algae behind the ladder. All other symptoms were perfect including a clean filter.

Using the pool calculator and with a residual FC level of 2.5 ppm, I added 1 lb of 65% cal-hypo (CH = 250), and 75 oz of 12.5% NaOCl to raise the FC to >16 ppm.

1.) The water became very cloudy after adding the cal-hypo.

2.) The FC level went higher than calculated to 19 ppm

3.) The next morning the water was sparkling clear but some white sediment on the floor and the DE filter pressure rose 9 psi and flow was decreased.

4.) After the overnight everything else is great:

FC = 18.5
OCLT = .5
CC = <.5
pH = 7.6
TA = 120
CH = 250
CYA = 45

 

[Richard320]

Sounds like everything is normal to me.

The green you saw was just the tip of the iceberg - there was doubtless lots more algae just looking for a place to stick. You just zapped it and the white stuff is dead algae. And now the filter is catching it all and loading up. You've passed two of the three tests; the water is clear, the CC<.5, and you need to keep the FC up all day and run an overnight test tonight to see if you're done.

You probably ought to backwash the filter, too. I expect the pressure will only get worse, especially if you vacuum up the algae carcasses.

 

[Bama Rambler]

If you haven't baskwashed, I'd go ahead and vacuum and then backwash and recharge the filter. You'll probably have ot do it again but that'll get rid of a lot. Then as Richard said, run the OCLT.

 

[Whatrymes]

The green you saw was just the tip of the iceberg - there was doubtless lots more algae just looking for a place to stick. You just zapped it and the white stuff is dead algae. And now the filter is catching it all and loading up. You've passed two of the three tests; the water is clear, the CC<.5, and you need to keep the FC up all day and run an overnight test tonight to see if you're done.

So last night's OCLT does not count??

 

[mynewpool]

whatrymes,

I think he missed the oclt in your test results. Most people do not list it within their test results. If that OCLT result was from testing the night before and the next morning, is counts.

 

[Bama Rambler]

We also like to see both sets of numbers. The evening and the morning results for FC & CC.

 

[Whatrymes]

We also like to see both sets of numbers. The evening and the morning results for FC & CC.

Sorry.

Sunday 6:00pm:

FC = 2.5
CC = .2
pH = 7.6
TA = 120
CH = 250
CYA = 45

Water was beautiful and sparkling but a small amount of green algae hiding behind the ladder.

Added CL and it tested at 19ppm.

Monday 7:00am:
FC = 18.5
CC = .2

Thanks.

 

[linen]

Not to steal Bama's fire here, but I think you are doing the test wrong. You do the OCLT by measuring at night after adding chlorine (about an hour after), then add no more before redoing the test in the morning. Looks to me like you should still be shocking!

 

[Whatrymes]

Not to steal Bama's fire here, but I think you are doing the test wrong. You do the OCLT by measuring at night after adding chlorine (about an hour after), then add no more before redoing the test in the morning. Looks to me like you should still be shocking!

I guess I don't write very clear, sorry.

My FC was 2.5, shocked it to raise the FC to 19, this was all done Sun. pm. Next morning, Mon. am, tested again and the FC was 18.5 and CC ~.2. ??

 

[linen]

Sorry I missed the 19 ppm in your post.

Remember, shocking is a process and not a one time thing. If you still have algae, keep shocking.

 

[Bama Rambler]

Sounds like to me you passed. You should be good to let the FC come back down to normal levels for yoru CYA.

 

[linen]

Sounds like to me you passed. You should be good to let the FC come back down to normal levels for yoru CYA.

Hey Bama,

The OP stills sees green:

Water was beautiful and sparkling but a small amount of green algae hiding behind the ladder.

Should he really stop shocking yet?

 

[Bama Rambler]

I missed the still seeing green part. I thought they were past that. If they're still seeing green then either they didn't do the tests correctly of the green is not organic.

I'm now thinking another OCLT is called for.

 

[Beamup]

I've passed an OCLT (multiple times) with algae in the pool and visible. Specifically mustard algae, and at normal FC levels. But when at shock level, I was failing. I would speculate that maybe the resistance of the mustard algae also means that it consumes less FC and so the OCLT can be passed anyway.

Since Whatrymes is AT shock level, that may not apply here. Still, something to be aware of.

 

[Whatrymes]

Sounds like to me you passed. You should be good to let the FC come back down to normal levels for yoru CYA.

Hey Bama,

The OP stills sees green:

Water was beautiful and sparkling but a small amount of green algae hiding behind the ladder.

Should he really stop shocking yet?

Guess I'm a real dumb poster.

I shocked the pool because I saw green algae behind the ladder. I don't see anything now.

 

[linen]

Guess I'm a real dumb poster.

I shocked the pool because I saw green algae behind the ladder. I don't see anything now.

And I'm a real dumb post reader Sorry about that.

Sounds like you are good to go!

 

[Richard320]

whatrymes,

I think he missed the oclt in your test results. Most people do not list it within their test results. If that OCLT result was from testing the night before and the next morning, is counts.

That is correct.

I'm not always my sharpest before 6 AM...

 

[Whatrymes]

whatrymes,

I think he missed the oclt in your test results. Most people do not list it within their test results. If that OCLT result was from testing the night before and the next morning, is counts.

That is correct.

I'm not always my sharpest before 6 AM...

But thanks, you answered my original questions perfect.

 

[Whatrymes]

OK, got into the pool today and took a real hard look behind the ladder. No visible algae present, yeeha! I'm planing on keeping the FC level to be no lower than 4 ppm with a CYA of 50.

Thanks all.