Humidity in Tubs

How do you measure the humidity of the tubs without buy a hygrometer for each Tub. I havent found anything other than that. Or do I even need to measure the Humidity?
Thanks for the input

I think a hydrogmeter in each tub is really the only way to be sure you are accurate...unless i am unaware of another method? You do need to know your humjidity as it is pretty important for their health. There are health problems associated with both too much and too little humidity.

Just get a $12 accu-rite from wal mart. It does temps and humidity.

One per tub works for me...

There are alot of variables which can affect the humidity in the tubs, even in the same room.
1) tub size
2) amount of holes spaced the same distance
3) amount of ventilation air moving through each tub
4) amount of substrate in each tub
5) amount of water in each tub

Those are the ones I can think of off the top of my head...

My tubs have 3x rows of holes approx. 1 inch apart, substrate, water bowl, and a humidifier in the room set at 50% seems to work perfectly for me.

What would be a good hygrometer to buy? Not a dubble one because I already have a temp Gun but a good, low cost one I can Buy in bulk.