How cheap do you want?

https://www.amazon.com/Taylor-Digital-In...ermometer+wired

Put a weight on the probe, use tape or a marker to mark the wire in one foot increments.

www.hoosierpondpros.com


http://www.pondboss.com/subscribe.asp?c=4
3/4 to 1 1/4 ac pond LMB, SMB, PS, BG, RES, CC, YP, Bardello BG, (RBT & Blue Tilapia - seasonal).