Avast Marine Works Probe Holder 2 Standard Probes,1 Dosing Tube

The center compression fitting is useful for holding a small temperature probe like the one that comes with the Neptune Apex/ACjr. You can slice a piece of polyethylene R/O tubing and put the temp probe wire inside, then clamp the poly tube in the small compression fitting. The outer fittings hold any standard pH or ORP probes.

Here's a handy use for a pair of neodymium magnets, some compression fittings, and a little CNC-magic bracket. Combine them and you have a simple, secure way to keep probes in place and at the correct water depth. The magnets will hold through 3/4" glass, accommodating nearly every sump out there.