Read several posts that say PH testing is inaccurate above 10 FC. With a CYA of 100 + I have a target of 12 FC. I typically test after 6 pm when my FC has dropped to around 8 so is my PH test accurate or not?
PH testing above 10 FC
- Thread starter brownchristian
- Start date
When FC is between 10 and 15, the PH test is usable, but it will read a little higher than actual. There is no way of knowing exactly how much off it will be in your particular situation, typically somewhere between right on to 0.2 higher than actual. The error gets larger the higher the FC level is, and then somewhere between 18 and 22 it starts being wildly wrong and you can't use it at all.
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