[johnnyboy2476]

I have a Milawukee SMS 122 PH controller. However, the PH probe that it came with would not work in situations where there's almost no KH. Would upgrading to a lab grade probe work?

Next question. I'm trying to understand the role of PH a little better. If I'm using RO/DI water with no buffering capacity, it would take only tiny amount of PH up or down to increase or decrease PH correct? Now, hypothetically, if I set up two tanks with RO/DI water, one with PH of 8.0 and one with PH of 5.0 - both using tiny bit of PH up or PH down. If I suddenly transfer fish from one tank to another, would they die of PH shocK? I'm inclined to say NO. If the water was very well buffered, then PH shock would kill this fish. I'm just a little confused.

 

[johnnyboy2476]

The reason I'm asking is because I'm running a tank with near zero KH. Everytime I do water change, PH would swing wildly by a full digit. Yet, my fish seems to be okay. This is contrary to what I've read and that many warned that suddent PH change can shock a fish - and yet this is not what I'm observing.

 

[johnnyboy2476]

Update - anyways I got my answer from Tom. Thanks Tom. TDS change seems to play a larger role at water change.