Question about test kits

I'm a little confused about a couple of issues. Why do some kits require four drops of phenol red and oto while some require five? I have two kits (one came with the pool and another from Wal-Mart). I looked at the little vials and they don't look to be that much (if any) different in size. Do the testing solutions come in different concentrations? I vaguely remember when I worked a couple of summers checking pools for the local health department it only took three drops.

Also, what happens if I use a fifth of the water with the 5-drop kit and only one drop? 'Should last five times as long right? :D

LOL - just a little something that's been weighing heavy on my mind.

Hey, one more thing. I guess I'd better get Ben's kit because I don't see how you all are measuring 10, 11 and 12 in chlorine readings. Both my kits only go to 4 or so. I can't remember the exact number but it's no where near 10. Thanks.

DS,

Ben's kit has the daily Cl test that require five drops. (OTO) It's good up to about 5ppm.

Additionally, it has a completley different test (FAS/DPD....much more accurate) that will test in ranges well over what you would ever need. That's how you're seeing results of 10, 20, even 12.5....it's on the money and worth every nickel.

Thanks Dura. I appreciate your response.

Like you, my pool builder gave me a test kit (I'm sure he really didn't "give" it away as I probably paid $100 hidden in the price of the pool) that used 4 drops for PH and chlorine. Like you, I assume it was a concentration thing or something. As far as the chlorine test, I went through the same thing when I started reading post here. "How the heck are these guys coming up with al these high chlorine numbers?" Once I received Ben's kit, I found out that the 4ppm of chlorine I had was actually FC <3ppm and CC >1ppm! Boy was I headed for trouble and the pool was only a few months old. Ben's kit seamed a little pricey to me at first but once you look around at say a Taylor kit that will test for the same things it really is a deal. Knowing what I know now, I wouldn't hesitate spending the bucks all over again, even if the price were doubled. I must say, after looking at your great pictures a week or so ago, your water looks really good to have been guessing, which no offense intended, is what anyone does with only an OTO test for chlorine. Ben apparently is behind in shipping his kits but if I were you, I'd go ahead and order one soon.

Dave

OTO and Phenol red in these cheapie kits are pretty interchangable. I don't think you will see much, if any, difference in using 4 drops vs. 5! The difference might be in the amount of water the sample tube holds. Have you checked to see if they hold the same amount of water?

Thanks David. I'll surely purchase the kit.

Waterbear, I can't tell a difference in sizes in the tubes. They look about the same.