SLAM - odd numbers

[Mr Bruce]

Do the CYA test with your back to the sun holding the tube with 2 fingers at the top with the tube at your belt buckle. After you think the dot has disappeared, pour it all back into the squirt bottle and do it 2 more times. Average the 3 numbers. That will be close enough.

A FC loss of 5 for a whole day is excessive, never mind overnight + 4 hours

 

[simonoaks]

Yes, I do it like that......the need for my brain to get exact data does not work well with the CYA test lol.....just wondering why there cannot be a more accurate test method!

I agree with the FC loss..... in the past, I have judged it just right and let it drop naturally whilst still killing final organics, then tested at about 7ppm overnight and passed. It is a fine line of having enough FC to kill final organics and not enough to pass the overnight test

I will do test tonight while FC is lower (another measuring issue with high FC is that you simply cannot measure within .5 ppm with that many drops, and doing the .2ppm uses 100 drops of reagent.

 

[mknauss]

The CYA test should be done in full sunlight, your back to the sun. Hold the vial at the top with your fingertips at waist level. Fill to a line (say 90), Glance for the dot, if there, look away, fill to 80, Glance for the dot, repeat.

Good luck.

Just saw Mr Bruce post. Do that too!!!! Good job.

 

[simonoaks]

6.55pm - FC 13, looking good. We shall see in the morning. At least at fc 13 I will get an accurate test in the morning.

 

[simonoaks]

7.15am - fc 11.5. Looks like today will kill the last of it

 

[simonoaks]

7.30pm fc 12
7.00 am fc 10
Lost 2 overnight, so not quite there.

Is there any info that explains the SLAM fc level against CYA and the relationship? I mean say at cya 60 , we know fc slam is 24 . Does that mean that at say fc 18 it is not eating the organics and it can ONLY eat the organics at 24?

If it is eating organics even below SLAM level, then does that mean my current FC 10 could kill off the last of it , without raising all the way back up to 24?

Just trying to understand if the FC will eat the organics at any level or ONLY at the SLAM level, and why.

Thx

 

[mknauss]

The shock level FC is at 40% of CYA level. At that level, you get the greatest kill of organics without raising your effective chlorine in the water to harmful levels for people or equipment. Lower levels of FC still kill some organics, but at a much less rate. So the more you can stay at shock level FC during a SLAM, the quicker it will go.

Take care.

 

[simonoaks]

makes sense. thx
So there becomes a point where the FC loses the battle and then the organics take over again.

So, if my FC is 10, with a 2ppm overnight loss, do you tink that 10 is enough to finish the job , without raising again, or will that 10 not kill the organics in time before it drops to standard operating number of 5-6 ?

 

[simonoaks]

2pm - fc 8, added 2 gallons
3pm - fc 21

 

[mknauss]

You should maintain your FC at shock level based on your CYA level in the pool until you pass the three criteria for a successful SLAM.

Take care.