I'm not sure what the consensus on these here is, but I bought a Farm Innovators Pro Series Digital model 4250 in 2015 and I'm pretty sure I only paid $30 or $36 at
Tractor Supply, b/c I kept the receipt thinking I had 30 days to return it if it killed all the eggs (that first run I got 50%, but some of the eggs were 3+ weeks old.) It's online now for $130, and some of the reviews are ghastly, mostly due to temp spikes, I think. I do manage to keep my room temp pretty consistent; it may be warmer or colder depending on time of year, but during hatch I will keep it even.
My hatch rate has been consistently between 85-90% (even including infertile duds), which is better than what my hens get. Up until the last time, and that's due to a number of circumstances: I got the eggs off
ebay, and they were different sizes (which I know is a no-no); the ones from one seller were all fertile; the other gave me 5 extras, which was cool, b/c 5 eggs were infertile. I had to be gone the last 4 days before they hatched and had a friend coming by once a day to check humidity/add water. And I put the sensor on the right side instead of the left on top of the egg; it may have gotten moved some by the turner in my absence.
It holds 41 eggs and is styrofoam. I haven't attempted more than 25 at a time, and I usually keep them in the central part of the hatcher, more toward the back than the front; around the element. The crucial thing seems to be where the temp sensor is located. I tried several things, and am still tweaking, because I think my last hatch got too hot due to the fan having dust on it and not properly circulating (I had 2 pippers die in the shell after perforating around, which was unprecedented.) They also hatched a day early and the first batch of eggs had gave me one that was blind in one eye and another that had wonky toes that bent all over the place and were too long (this was the group with the 2 that died pipping and they were smaller eggs.) The other group hatched all the fertile eggs, save one, but my palsy baby Flip came out of those, plus another which developed cross-beak (Flip also has crossbeak now) and 2 others with lesser beak deformities which I suspect were due to inbreeding.
I've done it rotating the eggs and not rotating; can't tell a difference. Having the sensor up higher definitely makes it cooler over all. I've done it a couple of times with the sensor on a particular egg that seems to be mid-range (right side seems hotter than left also for some reason; possibly due to the heat coming off of the turner motor,) I rigged it with strings going up, down, and to either side so I could move it inside the hatcher without opening, but sometimes it catches and has to be lifted a little bit. I've done it by hooking the sensor on the other wires up in the warmer air (thermometer will read up to 104 in top chamber when it is actually several degrees cooler where the eggs are. I will say it normally does better when I fuss over the eggs, though I know I'm not supposed to; having the humidity a little high hasn't hurt, and cooler is probably better with this one. Size of eggs makes a difference too.
I also use bleach; I use the spray bleach; take it outside and hose it down, then wipe/scrub out the the stained places with a cloth.
