I have a bottle of Phenol Red lying around from the test kit given to us by the store that sold us the pool. It's a pretty dumb test kit, only has an OTO and PH test. But I don't want those reagents to go to waste if they don't have to. So using the Phenol Red when my TF-100 runs out would be no problem, correct?
Phenol Red is Phenol Red, correct?
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Not all brands of Phenol Red are created equal. Phenol Red is very sensitive to interference from chlorine. The better brands contain reasonably effective chlorine neutralizers and are good up to an FC level around 10. While some of the less expensive versions can be thrown off by FC levels as low as 3. So, at low FC levels they are all the same. But at higher FC levels they can vary rather dramatically.
That's what I figured. Oh well, no use using something that will give incorrect results. I keep my chlorine around 4 so that's no good. (CYA 30, in case you were going to lecture me about low chlorine 
- I need to get my post count up, not many people take me seriously yet!)
- I need to get my post count up, not many people take me seriously yet!)I just wanted to follow up on this. I decided to do a side-by-side test with that free cheapo kit and my Taylor basic kit (the one that comes in the TF-100). Filled a bottle with pool water and filled both vials. Put the drops in both. Taylor came out at 7.2 (yes its always low and I added Borax after it) and cheapo came out as....a color that wasn't even on the color comparator. It wasn't the 7.2 mark, it wasn't lower than 6.8, it wasn't above 8. It was just a weird color. Needless to say, stay away from "Poolstyle" brand testing supplies.
The phenol red in the OTO Taylor kit is not the same phenol red that Taylor sells to go with their pH test block. I have to use something like 20 drops of OTO phenol red to get a comparable color to the Taylor. Largely due to the sample size. The Taylor pH block uses 44ml of water, while the OTO uses more like 10ml. Both take 5 drops of their respective phenol red.
Point being, there absolutely is a difference in phenol red strengths and test kits. I still like my Taylor pH block and phenol red better than the OTO though. The color is richer, and easier to read.
Point being, there absolutely is a difference in phenol red strengths and test kits. I still like my Taylor pH block and phenol red better than the OTO though. The color is richer, and easier to read.
frogabog said:
I've never had a trouble reading the OTO PH level. Maybe its my young 17 year old eyes, but I find that its easy to read with that little white paper they include in the kit.
This was comparing 2 test kits themselves. I didn't use the off brand Phenol Red in my Taylor OTO Block, I used it in its own cylinder and still got wonky results.
One of the nice parts about having both the Taylor block and the OTO block is that the ranges are different, so when and if the color seems off or between points on one block or another, running a second test with the other block confirms an in between reading.
The Taylor OTO block and the Taylor pH/CYA block use different pheno red reagents. Both are Taylor, but one is designed for the smaller OTO block. I don't really have trouble with either, but I prefer one over the other for general use. (plus I have a 2oz bottle of Taylor phenol red that should be used, at $6 it made far more sense than the .75oz bottle at $5)
The Taylor OTO block and the Taylor pH/CYA block use different pheno red reagents. Both are Taylor, but one is designed for the smaller OTO block. I don't really have trouble with either, but I prefer one over the other for general use. (plus I have a 2oz bottle of Taylor phenol red that should be used, at $6 it made far more sense than the .75oz bottle at $5)
The two Taylor reagents differ only in concentration. The view tubes are different sizes, so you need different amounts to get the same color saturation. They vary the concentration so you always add 5 drops when using the reagent matched to your view tube.frogabog said: