Where is my chlorine going?

[BackyardAquamarine]

Ok, I've got enough CYA in a sock to bring it up to 30 and have the filter running.

It amazes me how quickly the sun knocks down the chlorine. I tested it again two hours later and it's already dropped two points.

 

[BackyardAquamarine]

The TF-100 came today. I didn't have time to check everything yet, but FC was 1, pH was 7.8, and CC is 0.

I added 2c of 10% to bring the chlorine up and will retest in a bit as well as do the rest of the tests.

 

[BattleOfYakima]

Doing good! Look forward to test results! Friendly reminder, now you can aim for FC target range for CYA 30 on the [FC/CYA][/FC/CYA].

 

[BackyardAquamarine]

Okay, here's what I have:

FC - 4.5
CC - 0
pH - 7.8
TA - 200
CH - 75
CYA - 20-30 (I think it's closer to the 20 side, but I'm still getting the hang of reading this one)

The CYA I put in the other day hasn't completely dissolved yet, so there may still be some more of that to be released.

Edit to add: I'm not sure why the TA is so different today from what I measured it with the test strip. I assume either the test strips were off or I made a mistake doing that test tonight.

 

[BattleOfYakima]

I'm not sure why the TA is so different today from what I measured it with the test strip. I assume either the test strips were off or I made a mistake doing that test tonight.

Test strips usually off.

What really helped me master the testing was this page here: extended-test-kit-directions. It explains how the cya test must be done in bright sunlight, for example, and holding tube at waist height, in your shadow, and only glancing down, not staring. You'll learn fast!

Since you added the CYA, start chlorinating like CYA is 30 until your test shows it above 30 (31+) then treat it like 40. always round up to the next multiple of ten, not nearest.
So use PoolMath to help you bleach it up to high end of target range for your cya, according to [FC/CYA][/FC/CYA]. Then, in a day or two, after we get the CYA stabilized at 30+ and FC to match, let's do the Overnight Chlorine Loss Test again to see if you've got some hidden algae or not.

 

[Mike1162]

Looking good! CC of zero is exactly what you want. Tonight or tomorrow night perform this test:
https://www.troublefreepool.com/content/136-perform-the-overnight-fc-chlorine-loss-test-oclt
Congrats - you are well on your way to a Trouble Free Pool.

 

[BackyardAquamarine]

It's supposed to rain the next couple of nights. Can I do the overnight test when it's raining or do I need to wait?

 

[BattleOfYakima]

Great job making that connection and asking! As long as the OCLT procedure doesn't mess up your schedule, you can absolutely still do the test, and just remember that IF you fail, it could be because of the rain, but if you pass, you pass despite the rain! If doing the OCLT is rough on you, delay to a dry night.

Here are some quotes from our moderators and experts about rain and oclt that further clarified things for me when I wondered the same thing:

Depends on how much rain and how much debris is blown into the pool. Make sure the pump is running at least 30-60 minutes before you test in the morning to mix the rain ... although ideally in my mind you would leave the pump on all night.

(regarding 1.5 inches of rain)With that much rain possibly, but it doesn't matter. If the OCLT is failed then a SLAM is not over regardless of any possible interference.

I would wait and test when there is no rain in the forecast. Rain can wash organics into the pool and cause OCLT to fail. You won't know if it failed from the rain or the organics still in the pool.

 

[BackyardAquamarine]

Even with the rain, FC was 3.5 this morning, so that sounds like a pass.

 

[BattleOfYakima]

At 9:36pm Yesterday:

Okay, here's what I have:
FC - 4.5

Even with the rain, FC was 3.5 this morning, so that sounds like a pass.

most pools that are in good shape only lose around 0.5 ppm FC or less overnight while some may show up to 1 ppm FC overnight. It's when you get over that amount that we consider that to be a red flag.

So, as long as you performed the FAS-DPD test to all best practices (the sample size is accurate, bottle is held upright and let gravity help the drops fully form, more here) this is a pass. Is the water crystal clear. Was CC 0 both tests?