where to put orp sensor and ph sensor

[Bigair]

befor or after skimmer? I find the readings are quite different

 

[Randy Holmes-Farley Verified Community Expert]

How much of a different in pH do you see?

I'd put it after.

 

[Bigair]

How much of a different in pH do you see?

I'd put it after.

before vs after
ph -0.1
orp -20

ph not that much
I use ozone, there should be still some o3 left, so causes a little hight orp after, but the water from returning pipe has an average orp level, so put orp sensor before skimmer might make more sense?

 

[shakacuz]

i have my ph probe in the return chamber of my sump opposite side/corner to my ATO line.

 

[dschuffert]

I put mine before the skimmer. I like reading the water coming in from the tank.

 

[Pvtgloss]

I put mine before the skimmer. I like reading the water coming in from the tank.

Same