OTO test questions.

[y_not]

I know OTO isn't recommended for the advanced testing required here on TFP to assess and troubleshoot your pool. But I do know many here recommend it for at least day/day CL dosing. Which is exactly what I'm doing.
*see my sig, TF100 soon.

In the interim, I have been using OTO to check & dose with 6% fresh bleach.
I have discovered that it has been lying to me, can it do that even if the re-agents are fresh?

>>>>Here's my testing procedure<<<<<
- I rinse it after every use /w tap water, leaving it sit open indoors in a cupboard /w the caps off, also rinsed.
- Before each use I swish it around really good in the pool and fill the vials, then shake them up, dump & rinse once more.
* Probably excessive, but I want to be sure it's clean.
** The sample tube plastic never gets cloudy.
- I then invert, go down about a foot next to the AGP Intex skimmer basket "intake", then upright the vial and remove, tapping out the water to the line.
* Doing it by the return is about the same result.

- I add my drops, wiping the tip 1st on my arm, even not wiping it doesn't change it.
* It also doesn't really matter how many drops or how small a sample size I use, it's all the same, finite difference when there is one.

- I check the sample as soon as I invert, sometimes it goes a bit darker after about 3sec. or so, sometimes it doesn't, so TC the same and if I let it sit for 2-3min for the true TC reading, sometimes it's actually lighter. HUH? Bleaching? Why?
* If the sample sits in the tube /w the cap on, inside it's cabinet for several hours or overnight, it goes completely clear. I assume that's normal?


<<<<<<Here's what's happening>>>>>
So today I checked it about 2pm, got a very light yellow, like ice melted, diluted lemonade left in the bottom of a glass.
So it's 0.6ppm.
*Yes, low, I know, but you'll see why in a sec.

So I added 30oz of bleach about 5:00pm to bring it up by 4.3ppm for a total of 5ppm FC. This way I should get a dark yellow, no chance of orange as it's nowhere near that.

Well, so I thought. I tested it at 7pm, about 2hrs later.
What do I get? A medium orange, like a Jolly-Rancher orange. It's not dark yellow /w a tint of orange, it's clearly orange.

According to this link, that's probably about 15-20ppm.

What gives?

FC was low this afternoon because I have been seeing that it lies to me. I got about 5ppm yesterday before sundown, out in sunlight. Last night I got a reading of say about 1.0ppm in artificial light. Knowing that makes some difference, I just went with what I tested in the daylight & knocked off 1ppm to accommodate for a little extra FC loss. So I dosed it based on 4ppm. So 2cups of bleach.

Sometimes this works out, sometimes it doesn't, but it seems to be better overall than really believing the test at night. Otherwise if I really believe what it tells me, I get a nice orange color, waiting 30min to an hour before testing.
Is that enough time with my Intex pump for it to mix up?

So I'm a bit lost, I know OTO isn't terribly accurate and a lot of people have problems judging the different shades of medium to darker yellows. But the low, light yellows are EASY!!
It's even failing on that.

Advice, suggestions would be GREAT!!
Thanks.

 

[Leebo]

By any chance do you know your current CYA level??

 

[y_not]

Oh yeah, unless it's in tap water, it's right at 30ppm.
Because I started /w a fresh fill and added that much CYA via a sock.

So I dose to 7ppm, that way if I loose 50%, I'll still have .5ppm above the minimum.
*Thanks frogabog.

 

[Leebo]

Here's my suggest for a pool your size.

Assuming there's a 30ppm CYA level in your pool you want to keep it between 2-6. Test daily still as you are....but don't worry about the water so much. If your test shows just about any chlorine in the pool.....go swimming. If it's clear add 4 cups bleach and call it a day. You've got a HUGE advantage in your pool that if it ever goes green you are able to simply dump the water and start over.

Now for your "issue". I've found that testing against a brightly lite solid object works best. For me....I use a cloud free spot in the sky. A white piece of paper also works fine (I also use a poster board for the TA test). The OTO test is VERY user based, and in time you'll get the hang of it. It sounds like maybe your reading of .6FC could have been incorrect causing you to add more chlorine than needed. Give it a day or two and see how much it comes down.

 

[y_not]

Here's my suggest for a pool your size.

Assuming there's a 30ppm CYA level in your pool you want to keep it between 2-6. Test daily still as you are....but don't worry about the water so much. If your test shows just about any chlorine in the pool.....go swimming. If it's clear add 4 cups bleach and call it a day.

That's just about what I have been doing, except apparently I was doing it based on a CYA level of 40, as per frogabog's recommendation. She was thinking I put in 40ppm CYA, I only did 30ppm and missed the fact that she was basing it on a higher ammt. OOPS! Can't believe I didn't catch that.

So I'll dose it to a total of 5.5ppm each night, that way I have a .5 buffer @ 50% loss. Not that I can test that preciesly /w this, but I can dose it that way. Unsure if I'm loosing that much each day /w out the FAS-DPD test, but I'd rather air on the side of caution.

With what I have been doing, the water looks great!! Save for the double vision cloudiness that's under water, which I'm pretty sure is caused by calcium from the fill water. Waiting till I get the TF100 to diagnose that, as it has been that way since I filled it, so I know it's not algae. No slimy walls or anything.

You've got a HUGE advantage in your pool that if it ever goes green you are able to simply dump the water and start over.

My plan all along has been to treat it like a really big, full size pool, because I plan on one day having one.

But for sure, if it all goes to pot & I have to drain it, I will. The water is cheaper than cleaning up a swamp in this size pool.

Now for your "issue". I've found that testing against a brightly lite solid object works best. For me....I use a cloud free spot in the sky. A white piece of paper also works fine (I also use a poster board for the TA test).

Yup, that's exactly what I do, a white piece of paper that is. Using the sky is an interesting idea, I'll have to try that.

The OTO test is VERY user based, and in time you'll get the hang of it. It sounds like maybe your reading of .6FC could have been incorrect causing you to add more chlorine than needed.

Indeed it is, I believe though, that it is only as good as the quality of the reagents and the color key on the tester. Unless of course you're so awesome that you can tell without the key.
Both of which I think are horrible on mine, the company even admitted to using different suppliers for the reagents as well as the suppliers changing the color keys to match the other company's products that they make. WHAT?? WOW!! They shouldn't even be selling them if they're that way.
It's KemTech out of Ontario, California btw.

I think I'd have a much easier time /w the OTO test if I had the basic Taylor block, which I'm anxious to get that in the TF100 kit and do comparisons. I'm certain this kit is going to be at fault.

As for that 0.6ppm color, I think it's the reagent. As it was clearly that slightly limey, really clear, crazy washed out yellow.
The only color I have had trouble seeing a difference on is 1.5 & 3.0ppm, they look too close. I have looked at a better block and I could tell the difference between them.
I had bought reagent refills and ever since then the problems ensued with the OTO side. Before, I didn't have these problems.

Give it a day or two and see how much it comes down.

It only takes until about noon the next day, maybe sooner, we get full sun on it almost all day.

 

[y_not]

BTW, Did anyone, somewhere, ever bother to take photos of samples at the different PPM levels on the OTO test?
I have tried to find examples of samples, but nothing!

 

[JasonLion]

The colors don't photograph well. There always seems to a some color shift in the photo process that is impossible to correct for.

 

[y_not]

I wondered, aren't cameras funny that way?

Thanks Jason.
Always so very helpful, love your forum. A good place for a nerd to hang his hat. :-D

 

[Leebo]

It's not just the camera, but the colors will be altered some with different backgrounds. When holding it against a white background the colors will be different than holding it against the sky.

 

[y_not]

Yup, exactly.

I tried your sky method, seems to work pretty well, although it is definitely a different shade than using a white paper in full sun.

Does anyone know why the following happens?
The almost immediate bleaching & then the overnight bleaching.

- I check the sample as soon as I invert, sometimes it goes a bit darker after about 3sec. or so, sometimes it doesn't, so TC the same and if I let it sit for 2-3min for the true TC reading, sometimes it's actually lighter. HUH? Bleaching? Why?
* If the sample sits in the tube /w the cap on, inside it's cabinet for several hours or overnight, it goes completely clear. I assume that's normal?