SLAM - the math AND the reality

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7/23/15

6.20 am
FC 25

So, gone from 2 ppm to 4 ppm loss on overnight test.

As I have been maintaining SLAM at right level the whole time, how can it go up ?

Only thing I can think of is that we had a massive storm at 6 pm yesterday - about 2 inches of hard rain. As I have a screen, there is no visible debris, however, could it have pushed tiny particles into the pool like dust, pollen etc ?

If so, can that cause the extra loss?

As keeping at the right levels at all times, and got to just 2ppm loss overnight, and just 4 ppm loss during the day, how can I then suddenly have 4ppm loss overnight ? Algae cannot grow at shock levels , right?

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Man, I don't know why your getting a 5ppm spread like that. With the average of those being 24ppm your range is 20% of that.

I've never gotten more than 1ppm difference between consecutive readings, but I've only done 2 or 3 at "normal" FC levels.

Dom
 
I know. Crazy , right lol. I am even using a syringe to measure the same exactly. Do power the same , each squeeze on drop the same. Even tried both 10ml and 5ml a few times too. As it is impossible to accurately measure at SLAM levels, I guess I will just let it drop down to around 10, then do the overnight. If it fails, I will just raise it back up again.

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Are you thoroughly rising the test cylinder after each test? I usually rinse the chlorine cylinder at least 5 times (using the pool sample water) before repeating the test. Also want to make sure you are holding the reagent bottle vertically while dispensing the drops. You're probably doing this, but just wanted to make sure.
 

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Why do this to yourself? Do ONE test and call it good! This is NOT exact science due to the nature of the bottles and containers.

Some drops will be this big due to pressure put on the bottle, angle of the bottle, etc.

The containers are not super cleaned between each test so..............

There is a +/- at work here. It works for what we need it to.

Just breath and swim in your clear pool!

Kim
 
The problem is that you should not stop the SLAM until you pass the OCLT . That means getting less than 1ppm loss. You cannot measure that accurately at SLAM level. If you get different reading on the same sample , then there is no way of telling which is the correct one. Fine for topping up on bleach during slam when you can be in a ballpark. Different when you have to be literally exact.

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The most common cause for this is not taking the FC test to it's complete endpoint. Have you read the extended instructions? Do you understand how to get to the complete endpoint of the test?
 
Hmmm, could you post a link to testing please ? I just now found out, reading another thread that on the TA test, you do not stop just as it goes from clear to pink, but until it stops going darker . Not that is is relevant to SLAM , but still...I should read up on it. I watched a youtube video when I first started out a couple of months back

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Ok. Try again , for overnight

7/23/15
Fc 16.5
Fc 17.5

Only 1 point spread , call it 17.
Click to expand...
I am not sure what this post means.

The OCLT involves two FC tests taken several hours apart.....is that what you did? Be clear. "Call it 17" is further confusion for me.
 
As the margin for error in testing high FC numbers is ofter bigger than the 1ppm needed to pass. I often take 2-3 readings of same sample , that was the 3 consecutive readings I got with last night's test. As there was a 1ppm spread, I took the average.

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