Drop test vs oto

[Thesil]

I'm confused: I did the basic test for chlorine and it read 5ppm
Then, just for kicks I did the drop test and my reading was 1.5 how can this be ?

 

[jblizzle]

Did you do the CC portion of the FAS-DPD test too?
This does seem pretty suspect.

 

[Thesil]

Yes, first it was clear then turned pink so I added reagent and cc was 1

 

[JasonLion]

The simpler OTO test (shades of yellow) measures TC (FC + CC). It is also nearly impossible to distinguish between anything between 3 and perhaps 8.

If your FC is 1.5 and CC is 1.0, that means TC is 2.5, which is going to look a whole lot like 5 on the OTO test.

 

[Thesil]

Ok, so I'm wondering why my FC is hanging around 1.5. My cya is now close to 70 after adding stabilizer. All of my other readings are good. Should I turn my % level higher on my SWG or add chlorine or do nothing.

 

[JasonLion]

Yes, turn up the percentage.

 

[JVTrain]

Turn up the % level or increase run time. You need to have at least 3 in there all the time at 70 CYA with a SWG.

With a CC of 1, you might look at SLAMing the pool too. Should be a quick one and worth the effort. Let the experts guide you for sure on this though.

 

[duraleigh]

If your water is currently crystal clear, you could bypass the SLAM for now. I would suggest a one time dose of liquid chlorine up to around 6-10 ppm as an attempt to rid yourself of that 1 cc. Do NOT use the SWG for this. Simply put the chlorine in the pool and run your FC and CC's test in about 48 hours.

If the 1 cc's result is still there, them I think you need to SLAM.....again, not with the SWG but with liquid chlorine.

 

[Thesil]

Water is crystal clear. Cya is now 70ish. I added liquid chlorine a little while ago. I'll test on sunday

 

[Thesil]

Hi dave. Thanks. Just wondering why the drip test first showed clear , that is, no cc's then turned pink maybe a minute or so later. Maybe a false cc reading because it sat for awhile ?

 

[jblizzle]

The test always does that ... ignore it. You need to complete the FC and CC portions of the test relatively quickly and then move on.

 

[Thesil]

Ok. Then my cc's are in fact 0