I think it's pretty subjective. Normally, the bigger the better but still subject to how the setup was done in order to make it effective regardless of the size!
Hi minireef, welcome to the club! U need to place your Density probe in your tank for 2 days or more prior doing a calibration. That will provide a better accuracy!
I have relocated the probe and use back the original probe to counter chk but still get the same weird readings! I have send my probe for verification!