So I thought I had a perfect humidity levels in the tank but I am calibrating all 3 of my hydrometers (yes I said all 3) and I found that my flukers digital one I have had forever is 14% high so my readings have been off for like 3 months or 4 months now, it was reading 85% to 88% and I kept opening the lid to let some humidity out but I was getting condensation on the walls so I figured it was right. My one with the dial from petco is 5% high which I have known since I got it a month ago. The one I got yesterday from walmart is 2% high which is digital is the best one and standing at 72%. So the one from walmart is at 72%, the flukers digital one is at 74% and my dial one from petco says 70% when I subtract what they were off by. Now I am worried about the humidity, I have never had to worry before and when I saw condensation I figured I was good. I really am upset about the flukers one being so much off and me never knowing about it because I never calibrated it (I know BAD me). The one from Petco is actually on the left side of the tank 1/2 way up, my flukers digital is on the right side 1/2 way up and the one from walmart is above the flukers one because when I found it to be that off I wanted to see what it really was. One of the temp/hydrometers is going in my 10 gallon once I have it back up and running so I won't have 3 in the 20L but I had to see for myself. I would like to see a humidity level of around 75% to even 77% so now I am not sure what to do. I guess I am going to be getting some moss and making a moss pit so I can get the humidity levels up. I plan on also keeping the walmart temp/hydrometer and the petco temp/hydrometer (2 seperate ones) in the main tank but do you think I should get another one from walmart for the 10 gallon or should I subtract the 14% and use the flukers one? It just is irritating that I have 3 in there and only 1 is pretty accurate. That darn flukers one is so expensive too and it works so badly. I had problems with the battery when I first got it and now this. I feel so bad not calibrating it when I got it. Oh well we all figure it out sometime that we must calibrate, let this be a lesson to everyone that you MUST calibrate your gauges when you get them.