Quick question in regard to using OTO testing


Bronze Supporter
May 29, 2019
So before I got my real test kit, I had picked up an HTH 6 way test kit. Obviously it does OTO and not FC or CC.

However, since I started following TFP, got my real test kit, and switched to liquid bleach, I now test and my CC is usually at least 5 (target is 9 for my high CYA), and CC is usually .5 or 1.

So my question is this: since my system has stabilized, can I use the OTO testing daily to make sure I didn't have a lot of chlorine depletion, and then use the real kit ever 2-4 days to verify that? I did this yesterday. After hand skimming, I checked OTO. It was 10, which suggested to me, based on my recent testing, that FC was 9 or 9.5 and CC was .5 or 1.

I don't trust this implicitly which is why I'll still use FAS-DPD every 2 to 3 days.



TFP Expert
LifeTime Supporter
Jan 6, 2010
San Dimas, CA (LA County)
Yes, you can.

I'd suggest you wait a week or two before you get lax about testing; make sure you really know your pool's chemistry. There will come a point when you can tell what numbers you will get before you've let drop one out of the bottle. On everything. Even after you just added water. That's when you can get lazy about testing, because you know without testing what your pool is going to need. Actual testing will only be something you do to ensure there is no problem. Day-to-day stuff will be largely on autopilot.
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