How to verify if PH is below 6.8

[SPP]

Guys,

I alread tried the search function but the very mention of PH, the server said too common.
So need to bug you guys, sorry.

I can't remember which post it was ( I read too much within too short period of time ) but I think if a TA test conducted and the color suddenly changed to ???? color that means "something" was way too low. Is that "something" = PH ?

The PH tester we have is 6.8 as minimum, how do I read lower than that ? Or what can I use to detect if PH is lower than 6.8.

thanks

 

[JasonLion]

When the TA test goes red right off, the pH is at or below 4.5.

There are various other PH tests that will read lower values, for example various members of the Taylor K-1011 series or the K-1285 series.

If you have a base demand test you can get a sense of how low the PH is, though not an absolute number.

Generally, there isn't any need to know just how low the PH is, just keep raising it by 0.4 per step until it reads in the normal range.

 

[SPP]

Thanks Jason.
My Pentair test kit with 5 bottles is what I like to use for PH.
I always use #3 bottle to bring down PH ( acid demand test ) to make sure I read 7.6 properly. My eyes for some reason can't tell 7.8 from 7.6 properly. I am poor with shade of res it seems. In fact I get migrain sometime when my surrounding is highly bright red color or when neon sign of high red intensity keep flashing in my eyes from some advertising bill board and I am in indoor brightness level.

Any trick to use my 5 bottles pentair to do the opposite of acid demand ?
Bottles are :
#1 OTO
#2 Phenol red
#3 Acid Demand
#4 Chlorine neuralizere
#5 TA test

Later...