Temps for bubble cloner

So I've been lucky with my bubble cloner until recently. I added an intake to the veg room that is bringing in cold air, so my temps are 68-70 degrees F. I have a heat mat with a thermostat, but was unsure about what temp to set it to, and if I can put the temperature probe directly into the water. The clones are in 2 inch net pots with hydroton. Thanks!

78 Deg i believe is optimal. (+5/-10) Humidity also. I clone with room temp water.

As far as putting the probe directly into the water, I have a digital thermometer with a cable probe that can be submerged. Is it water proof? you probably can submerge it...

1 thing about doing the clones in net pots. As they develop roots, the roots will eventually grow through those openings. You may run into issues with transferring your clones to larger pots (breaking/ripping the roots).