It is important to understand that all of us test in a different routine and what works for you is what you should use. TFP's job is to teach Why you test and what to do about your results......not dictate a precise pattern.
I love this thread too and agree with the sentiment above. TFP is all about making choices based on the best available information and having options.
Joyfulnoise, with all due respect there is a flaw in your thinking about using the K-1001 DPD, namely that both it and the FAS-DPD test can bleach out at high FC levels, the OTO kit will not bleach out, it may look burnt orange, or brown, but will not bleach out. Now lets consider a real world situation where this can come in handy, someones SWG timer goes crazy and starts running at 100%, or the well meaning teenager adds way too much bleach to the pool. Now you get home and test the pool with the FAS-DPD, then the DPD as backup and both show little or no chlorine no, so you add even more, still showing none, you think you have something starting to grow in your pool, so you add even more, .... This is where the OTO kit can be a life saver, not in telling exactly how much chlorine you have, but telling if it is little/none or a whole lot. (pale yellow, vs schoobus yellow, or safety orange)
Unfortunately, for me, this is a weak argument (or "reason" if you don't like the word "argument"). First of all, it's an argument from the extremes - there is really no possibility of either of those situations occurring in my pool. Not only would the SWG not really be able to produce FC levels that high (since my pool is mostly uncovered) but anyone adding bleach to my pool to a level that would fade the reagents is doing so with intentional malice and not "accidentally" as it would take many gallons of bleach to get the FC that high.
While it is true that OTO will not bleach out, it also true that both the DPD-only and FAS-DPD reagents have fairly high fading points. For the DPD-only test, once can reliably test up to 10ppm FC and go even slightly higher using 50-50 dilutions without the reagent fading at all. Above 20ppm, you might have a problem with fading. As for the DPD-FAS reagents, those are stable up to 50ppm FC and I know this for a fact because I have measured FC's nearly that high.
What OTO could not do was give me a reasonably accurate FC level (and this seems to be the consensus opinion about OTO's accuracy). Just the other day, with just my DPD test reagents, I eyeballed the pink color to be between 5 and 7.5ppm on the color block. I called it 6ppm. I then measured the same exact water sample with the DPD-FAS test and it titrated out to 6.5ppm. I have also been able to distinguish the 4ppm color block quite easily as that would be the minimum FC level for my SWG pool. So, not only does the DPD test give me a GO/NO-GO visual of chlorine presence, I can also get a fairly reasonable estimate of my FC level that I'm confident in. I also have both the "High FC" comparator block (0-10ppm FC) as well as the midget comparator (0-5ppm FC) which makes doing dilution testing very easy. For people with non-SWG pools who run their CYA at lower levels (and use lower FC levels), the DPD only test is even easier to see color distinctions with at the low end (one can easily distinguish between 2-, 3-, or 4 ppm)
So, for me and my pool, I like to have a fairly quick and easy test to do daily that lets me ballpark my FC level rather than just get a visual confirmation of chlorine presence. Because OTO was not able to distinguish chlorine levels for me, I find the DPD test to be very beneficial for my daily pool care routine and the K-1001 retails for $7 on Amazon which, in my book, is a small price to pay for a very reliable test. And, as Dave said, isn't that what we are all really talking about here - what's the best way to take care of your own pool? I have no problems with anyone that chooses to use OTO as part of their daily routine. I did not find it useful for my routine and wanted something a little bit more accurate and I'm very glad that Taylor has a solution for that.
SO if the OP is looking for something to replace the OTO test with that is fairly reliable and accurate and not as burdensome as doing a full titration test, the K-1001 is a pretty good way to achieve that end, in my opinion.
Respectfully,
Matt
