Ph test block reading

[hillerji]

OK, Dumb question of the day. When reading the block, where does a reddish color fit into the block spectrum of colors.

I'm looking at it and it's red, rosey red. Now the block runs from low (pale orange) to high (grape colored)...I'm just not sure where my red fits in.

Thanks as always....

J

 

[Butterfly]

Hope this helps:

above 8.2 purple
8.0-8.2 purplish red
7.8 pinkish red with a hint of purple
7.6 red
7.4-7.5 red with an orange cast
7.2 orange
7.0 yellow orange
6.8 and below yellow

 

[HouTex]

Hope this helps:

above 8.2 purple
8.0-8.2 purplish red
7.8 pinkish red with a hint of purple
7.6 red
7.4-7.5 red with an orange cast
7.2 orange
7.0 yellow orange
6.8 and below yellow

I just started another thread with the similar question. So 7.6 is simply red? I don't recall ever getting a purplish red or a pinkish red with a hint of purple and certainly not plain purple. Maybe my max pH has been at 7.6 the whole time and I just didn't know it?

 

[Durk]

This is where I like the Acid Demand feature on the Taylor kits. When I'm in the reds and can't figure it out, I hit the sample with a drop of the acid demand reagent. If it goes to 7.4 or below I know I was in range and don't need to do anything. If I'm at 7.5 or above, time to do some acid. I can handle the lower ones, but the red zone is very confusing to me.

I assume the reagent is available anywhere and the Taylor manual with the table and instructions is on their website. It will work with the TFT kits, although most here will say it's 'unnecessary'. I still like it because it gets you out of the red zone.

I know that one drop of acid demand reagent has the same effect as adding one-third jug of MA to my size pool. It's even easier than poolcalculator.

But as I said, I'm in the minority.

 

[wetchem]

Re: pH test block reading

I had a student that was red-green colour blind and had a few other issues with colour separation (close shades/tints of a given colour).
What I did when I couldn't find a different indicator was use different background.
Taking a 3x5 white index card I found neon pastels (you might use crayons) and using the complimetry colour (ie for red use blue)
http://www.google.com/search?q=comp...9Goj88gTK-tDICg&ved=0CGYQsAQ&biw=1280&bih=768
Use the lightest shade you can and slowly increase the density ( I did this a a band on the card ) With today's colour printers you could just print out something from the url.

Now, this didn't help my student see red/green colours; however, what he could see was the change in shade when the end point of the titration was reached!

Once we found the correct backgrounds... I asked the arts department to cut lighting gels for a backlight for him to use. Totally freaky to expect one colour from an indicator and see something compleatly different - or black when there should be reds and clear when there should be yellows.

For red... start with the blue... try yellow, (even safety yellow chartruese) start with the least amount of background and increase the density of the colour.

-WC