OCLT timing

[Kellllllli]

I'm doing my first proper SLAM with my own FAS-DPD Taylor test. I had barely visible algea which cleared up in the first day, and now I'm on day 4 and water is clear with .5 CC. I have CYA of 50 and am adjusting FC to SLAM level 3-4 times a day. I did my OCLT test at 11pm and 7am and had 2.5ppm loss.

My question is about OCLT timing and the meaning of "direct sunlight." I'm in Austin, TX and Google says sundown is 8:30pm, sunrise is 6:30am. I am not a morning person and I typically sleep about 1am-8/9am in the summer. I don't want to wake up any earlier than is necessary, but I'm willing to stay up a bit late. So for the OCLT,

1. When is the latest time I can do my morning test?
2. When is the earliest I can do my evening test?
3. What's the minimum hours between the tests?

For example, would 9pm and 1am be sufficient? If not, are 7am or 8am acceptable times? Or do I really have to set a 6am alarm in the summer for days on end ?

 

[Oly]

Set your alarm, grab the sample, seal it up, put it in refrigerator and go back to bed. You can do the analysis at 8/9am. Don't quit the SLAM too soon, finish the job.

 

[Kellllllli]

I decided to wake up in the middle of the night and do it and go back to sleep. So I tested at 9pm and 4am and had exactly 1ppm loss, and exactly .5 CC. Yay! I think I passed, but I'm nervous because it was only 6 hours and it was the maximum acceptable loss amount. Would I have lost 1.5ppm if I went 9 hours? Should I keep SLAMing and try again tonight to be sure? Or am I overthinking it?

 

[dBsooner]

How does the water look? It is crystal clear? Is there any algae on the bottom? I’m in Oklahoma, and I did my last test of the night at 9:30pm or so, with my last addition of chemicals about 8:30pm. Then my first test in the AM was around 6:30/7:00am.

Exactly 1ppm loss in 7 hours isn’t bad, technically it’s a pass, but you’re not allowing the extra 2-3 hours of circulation to occur before testing. Did you brush the pool really good last night?

 

[Mdragger88]

Technically that’s a pass but you could Go another day to be sure you’re good to go!
Oclt’s suck but so does algae!

 

[Oly]

Follow through the process. Do you have a pool ladder? Does it have water inside not circulated in your SLAM? Attention to detail now will make your pool easier to manage all summer.

 

[dBsooner]

Follow through the process. Do you have a pool ladder? Does it have water inside not circulated in your SLAM? Attention to detail now will make your pool easier to manage all summer.

What do you recommend for this situation? Not going to thread hijack, you can DM if you’d prefer. I have the confer 7200 ladder with the hollow steps and rails. From the pics in her profile, she has the original metal frame that comes with the pool.

 

[Newdude]

C's get degrees, they say, but a borderline pass is only going to hurt you in a couple weeks if you ended too soon. IMO you want to graduate SLAM at the top of your class.

 

[Oly]

What do you recommend for this situation?

Her ladder may not have this issue, thanks for your observation.
My reminder is simply that pool algae nurseries are often over looked when working a SLAM and can be the source of another outbreak. Ladder frames, pool lights, pool toys, mats, covers, skimmers have all been shown here to harbor algae.
What you can do with water in hollow ladders is first remove and drain them. Open access points to allow cleaning with a chlorine solution and improve water circulation after reinstallation.

 

[Kellllllli]

How does the water look? It is crystal clear? Is there any algae on the bottom? I’m in Oklahoma, and I did my last test of the night at 9:30pm or so, with my last addition of chemicals about 8:30pm. Then my first test in the AM was around 7:15/7:30am.

Exactly 1ppm loss in 7 hours isn’t bad, technically it’s a pass, but you’re not allowing the extra 2-3 hours of circulation to occur before testing. Did you brush the pool really good last night?

The water has been crystal clear and perfect looking for several days. I brushed well yesterday (and every day this week). I run the pump 24/7.

But I've been battling algea for months. I wasn't following TFP in the past, but I would double shock it and it would look perfect just like this . . . then it would come back in a couple weeks. So I'm really excited to complete this SLAM correctly and actually eradicate the algea and I want to be sure it's complete!

 

[reggiehammond]

Great! I always think that a SLAM is best done when you go a few extra days, just in case. The pool won't be consuming excessive chlorine, so just keeping FC at slam level is smart, even once you've passed all 3 exit criteria.

 

[proavia]

Getting up at 6am or 6:30am isn't the end of the world if you do it for a few days - especially if it means you are in a better position to keep the pool algae free.

For the Overnight Chlorine Loss Test - the nighttime test should be just after sunset and the morning test should be at sunrise and certainly before any sun hits the pool.
8:30pm-9pm
6am-6:30am
This will provide 9+ hours between the two tests. With only a 6-7 hour time span and a loss of 1ppm, it may be best to have a longer time between tests to be sure of the overnight loss.

After you pass ALL THREE test criteria, be sure to target a CYA of 40-50 (maybe even 60) to keep the chlorine from burning off so fast in the Texas sun/heat. Use the FC/CYA Levels to determine the correct FC target for your CYA level and shoot for the top end of the target range.

 

[PoolStored]

Set your alarm, grab the sample, seal it up, put it in refrigerator and go back to bed. You can do the analysis at 8/9am. Don't quit the SLAM too soon, finish the job.

FC, CC, and PH can all change fairly quickly if you leave the sample sitting. TA, CH, CYA, Salt, Borate all stay more or less the same when the sample is left sitting.

It is recommended to test sample soon after taking it from the pool and FC/CC and pH should be done first.

 

[Newdude]

The irony of cutting corners with the OCLT, is having to wake up early again if it fails because you cut corners.

Whether it's storing the sample, or hitting the snooze button a few too many times, you are very possibly sticking it to yourself. Tomorrow you isn't going to like today you, at all.