I have a Hovabator 1588 that I purchased back in the spring. It has run constantly since. The first several hatches were great and had no problems. The last three hatches I have done have failed miserably. The first two bad hatches had temps at 99 and humidity at 45-55% days 1-18. Temps for 18-21 stayed at 99. Humidity spiked to the high 90s when I added water and then regulated back into the low 80s/high 70s when I opened the top plug for a bit. I had no chicks the first round and three the second. The remaining chicks in both hatches looked to have died around day 18 when I added the water. They were formed, but had not finished absorbing the yolk sac. This last time I tried the dry incubation approach (thinking that perhaps I was drowning them somehow). Temps at 99 and humidity in teh mid to high 30s. On day 18 I added a second glass of water and humidity again spiked to 90s. I took the second glass out and they dropped to mid 50%. Today is day 21 and nothing is happening (and I realize that it is early, but in my earlier positive hatches, chicks started out on day 20. At this point I should have some pips at least or some cheaping. I've got nothing.). What am I doing wrong? Why were my early hatches so great and these later hatches no good? The only things different would be that I am not turning these by hand. I've been using the egg carton method and tilting the whole carton from side to side. That shouldn't change who hatches though. Right? This is making me crazy!! I have changed batteries in the thermometers and hygrometers. I have cleaned the bator with bleach between hatches. I have run the water cups through the dishwasher on saniwash. The water I add to the cups is always hot and not room temp. The first couple of bad rounds the eggs were from my pen (like all the good rounds earlier in the summer). This set is partially mine and partially eggs from someone else. And according to day 18 candleing, everything in there is developing. Or rather was developing. Who knows what's going on now. Sigh. What else could have changed? I am stymied.