JasonLion said:
CarlD - waterbear is quite correct that we tend to discourage the use of OTO with dilution here at TFP, but that isn't a hard and fast rule. There are a few situations where I have recommended OTO with dilution.
We are certainly willing to explore the relative merits of the various approaches further to see if the general sense around here that OTO with dilution isn't worth it is valid. The one rule we do have that applies in this situation is that the more technical discussions, such as exploring the merits of OTO with dilution, should happen in The Deep End and then the conclusions can be brought back to the rest of the site.
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Using OTO with dilution does have some merit, but more and more I am finding that it distracts more than helps. There are a couple of different issues.
1) People who get over the hurdle of buying a better test kit are nearly always really happy that they did. There seems to be some irrational resistance to purchasing a better test kit, presumably because of the price tag. That is not rational because a better test kit will save more than it's cost in chemicals in the long run. Offering an alternative to a good test kit, such as OTO with dilution, tends to strengthen the irrational belief that a good test kit is not worth it, which frequently means further delays before the complete resolution of the original problem can occur.
2) High CC levels can completely invalidate the results of an OTO test. High CC levels are not common when fighting algae, but they do occur in some cases. Using OTO with dilution will result in completely invalid results when high CC levels are present. The preference at TFP has been for techniques that are trouble free, which means avoiding taking a gamble on the CC level.
3) OTO with dilution is dramatically imprecise. When measuring TC levels around say 15, the OTO test with dilution can be +-6 or worse. While it is possible to aim for levels high enough to be sure you hit 15 even with that imprecision, and so effectively shock the pool using OTO, it wastes chlorine. Further, there are other tests, like the overnight FC loss test, that are simply impossible with that level of imprecision.
All your points are excellent. I agree with all of them. With caveats.
Remember that when you are up to your back bumpers in alligators is a very poor time to remember that the objective was to drain the swamp--which is what the desperate person has with a wicked algae infestation.
You will NEVER hear me say that someone shouldn't "waste" their money on a FAS-DPD kit. You know that.
I got my PS-232 from Ben Powell back in 2001 and that was for a little 15'x3' round Intex donut pool--and even then I insisted that it was worth every penny and then some!
People mainly come here and to PF because they are looking for answers to a problem that the pool stores can't solve. They are usually in the middle of a crisis. If they are LUCKY, they have a kit like the WalMart 5-way drop kit, or can get one that day. They SHOULD order a FAS-DPD kit, whether from here, Taylor or Leslie's. But in the
meantime what are their alternatives?
[Edit by SeanB - Carl, I have explained this to you on more than one ocassion - the tf-100 is from tf testkits, and NOT "here" at TFP. TFP does not sell or profit from the sale of duraleighs kits. We just happen to think it's the best overall residential test kit.
[Addition by Carl: My apologies, Sean. Of course you are right--I keep forgetting because the name TF-100 is always looking like "TroubleFree" to me. And you do have a link to it but not to Taylor's or Leslie's, so it's a natural mistake. It's Duraleigh who sells them, not you. Sorry again.]
1) Test Strips--only now, after many years can I read a Hach or LaMotte strip (the only really reliable ones easily available) and get a reasonable idea of my FC, TC, pH, TA and CYA. In the ball park, but no better. For a newbie? They are worthless next to drop-testing. We all know that.
2) Pool Stores (who then try to intimidate them into buying clarifiers, phosphate removers, calcium increasers, and bags and bags of something called "shock"). But you have to get to them when they are open. I'll bet if you are there 2 to 3x a day they'll kick you out if you aren't buying stuff.
3) OTO Dilution
I understand that you don't want people to rely on OTO dilution as their main tool--clearly I've indicated that. But you cannot protect people from themselves who refuse to listen and learn. I, for one, am willing to put in hours helping someone who doesn't understand the steps but is TRYING. I try to simplify it and break it down.
But if a person refuses to follow guidance and keeps running back to the pool store and throws in all the garbage (see above) they sell him, against my advice, well, there's nothing I can do for him.
I had a dentist down in Northern Virginia who had a poster on his wall that said something like: "There is nothing the doctor can do that the patient cannot undo".