High FC Slam and Swimming

[Poolboy6]

I’m in the middle of my slam. I have not passed an OCLT yet but I know I’m close and may pause for a weekend pool party. It’s tuesday and cloudy. Pool party Saturday.

CYA is higher than I would like @ 80 so Ive been maintaining slam FC of 31.

My question is this, I’m concerned my FC will not drop by the weekend to be at a target of ~9ppm. What are my options? And are there concerns swimming in 20+ FC at CYA of 80.

FC 31
Ph 8.0
Alk 120
CYA 80

 

[pooldv]

Re: High FC Slam and Swimming

It is safe to swim with FC up to shock level for your CYA. I've done the swim and SLAM a couple of times. Nobody knew the FC was 28 ppm except for me.

 

[Texas Splash]

Re: High FC Slam and Swimming

With a CYA of 80, you are safe to swim up to 31. No need to let it drop really low.

 

[Poolboy6]

Re: High FC Slam and Swimming

Ok. Thank you. Also, I failed to test my Ph prior to the slam. It’s reading 8.0 at FC of 31. Can I trust that reading or is it impossible to tell/way off because of high FC..

 

[YippeeSkippy]

Re: High FC Slam and Swimming

No, you can't trust that pH test. The pH test is not accurate when the FC is >10. Best thing to do is catch it when your FC drops to less than 10, or let the FC drop to test.

Also don't bother performing an OCLT until you are perfectly clear... its a waste of reagents to do so earlier as you won't be meeting the other two elements for ending the SLAM: CCs < 0.5. , Clear water, OCLT of 1 or less.

Maddie

 

[Poolboy6]

Re: High FC Slam and Swimming

So does high FC skew pH up or down.

 

[Richard320]

Re: High FC Slam and Swimming

So does high FC skew pH up or down.

The reagent reacts with the chlorine and turns -- well, see for yourself:
Accurate pH test during shock levels with R-007?

 

[Poolboy6]

Re: High FC Slam and Swimming

How does high FC skew pH? Up or down?
When operating at a high CYA of 80 or 90 and a target FC of 10+, pH readings can’t be trusted. I realize it would be ideal to test when FC is below 10, but is there any calculation to determine the skew?

FC 31
PH 8.2
AK 120
CYA 80

 

[YippeeSkippy]

Nope.

Just like that picture of the comparator block in the other thread shows, it messes with it. Makes it look like pH is higher than it is and you might accidentally treat that with out realizing its a false result.

I know of no way to neutralize the chlorine so that the test is accurate.

Maddie

 

[Poolboy6]

But does it always skew HIGHER than what it actually is?

 

[mknauss]

Yes.

But it can be off by 0 to who knows how much.

It is just inaccurate.

 

[pooldv]

And a reading of 8.2 on a pH test that reads up to 8.2 could actually be much higher. 9.0 also looks like 8.2 because that is as much color change as the reagent can produce. I find that sometimes my pH reading is low when FC is high, maybe because the color is bleached out or something. I don't know, but i don't find that it always reads high.