Question about Ph meter

[Afghan Haze]

If I buy a new Ph meter from Amazon.com do I need to order the 7.0 calibration too?

 

[BigDawg]

make sure the pen is 2 point calibration. you need 4.0 and 7.0 calibration solution.

 

[NeWcS]

You should be able to go to your local hydro store and buy a 4 & 7 one time use. They come in these little bags. They are like $.50 a piece. Recl before every grow to see if your meter is drifting.

 

[daishere]

i check my calibration about every 5 batches of nuts. may be overkill but id hate to have nute lock out from ph.