Me vs. The Pool Guy

[Sparkle]

That would imply that you essentially need to get into the pool to do any testing, unless you have some rig that grabs water several feet out, several feet deep.

In think they mean half-way between the deep end and the shallow end, on the wall opposing the returns. The point is to get a representative sample, to the extent that that is possible (within reason).

Not sure I understand that question. All the tests are based on a known water sample size, such as 45 ml, 25 ml, or 10ml. As long as you're using the recommended sample size for the test, or following one of the known dilution/multiplication of results procedures, you should be fine.

I use my various vials and the Taylor comparator and fill to the appropriate amount required for the test I'm doing at that time.

The tests may be based on a known sample size, but the recommendations are based on user-reported measurements. You don't know that you are using the right sample volumes, you assume that your interpretation of the vial marks are correct. If you want to find out whether your interpretations are correct, try filling your vials with a syringe or some other accurate device that invites less interpretation.

Even if your sample volumes are correct, you can't know what the typical user does.

 

[Saturn94]

I grab my test water from the exact same spot each time.

I dunk my bottle in up to my elbow. I don't think I'm growing any more (46 ) so that should be consistent.

As long as you do it the same, you can just rely on your own test results and any changes should be accurate even if your actual numbers are off a bit.

Same here.

Same spot (deep end, away from returns), same depth, same time of day.

 

[Richard320]

Am I the only one who gets a mental image like this every time I see this thread title?

 

[eqbob]

In think they mean half-way between the deep end and the shallow end, on the wall opposing the returns. The point is to get a representative sample, to the extent that that is possible (within reason).





The tests may be based on a known sample size, but the recommendations are based on user-reported measurements. You don't know that you are using the right sample volumes, you assume that your interpretation of the vial marks are correct. If you want to find out whether your interpretations are correct, try filling your vials with a syringe or some other accurate device that invites less interpretation.

Even if your sample volumes are correct, you can't know what the typical user does.

Well, the empirical evidence through thousands of pools following this technique is that it works. As far as I understand the principles, they were built to not have to worry about things at a master chemist level. Someone will no doubt run the equation to say what the differential is if your off by a ml on the fill for a 25 ml sample (example), but you're just as likely to be off by other things you can't control...the size of your reagent drops, the heat they were exposed to, does a 6pm test every day really meant the pool got the same conditions, etc.

As far as a what a typical user does, think of the normal curve and the millions of test that have been done using these methods. Surely,smoke of them will be in the edges, but the vast percentage will be in the middle and valid. And it's worked for God know how many pools for who knows how many years.

There's certainly no harm in taking it to th level you are, if you enjoy it, but there's also no need, IMO. Which is worth as much as you paid for it...LOL. Same argument for the use of accessories, like a speed stir, use of liquid vs. solid stabilizer. The system is flexible enough so that people can make it their own and the principles hold.

If I'm wrong in anything I said, the true experts here will correct me.

 

[Sparkle]

A normal distribution of sample sizes may be good for the average user but it isn't going to help me much if improving my accuracy places me on one of the tails.

Either way it seems to me that the methods work well and I do try to follow the recommendations.