Humidity Control in Brinsea Maxi II Advance - Duck Eggs


Mar 7, 2017
Hey there,

I am borrowing the Brinsea Maxi II Advance to hatch 14 duck eggs. All is going OK so far (day 4 - with good development in 10 eggs), however I'm pretty upset by the lack of humidity reading on the machine. This seems like a basic requirement to me??

Anyway, grumpiness about this aside... I bought a hygrometer that would fit inside the incubator, as I've had issues with probe wires before ( - but I now realise, maybe this was not the best purchase? It is reading a humidity of only 25% :th

The only Brinsea instruction is to keep one side of the middle water well topped up for incubation, and then to fill the second well in addition for lockdown. This seems really imprecise to me... And yet searching through a few posts here - people do seem to have had successful hatches this way? It doesn't seem ideal to me and I'd hate to lose them to something so simple.

I have hatched duck eggs before, but not for some years now. And I had a humidity reader on that incubator....

So my question is, what now? Buy another hygrometer? Trust this one and add more water?? Or just blindly trust Brinsea??

I'm a bit confused. Please help! Thanks :)


Oct 18, 2018
If you don't trust the hygrometer, take it out and do the salt test with it to see if it accurate.

Put 1 tablespoon of table salt (100% sodium chloride) into a small dish and add 1 teaspoon of water. Stir to totally saturate the salt. It won't fully dissolve but it will look like a slushy. Don't use lite salt. It is sodium chloride and potassium chloride. I don't know if iodine will affect the reading but you should be able to find it without iodine.

Place the dish into a resealable quart plastic bag along with the hygrometer and seal the bag. Puff up the bag a little. Don't let the salt mix come in direct contact with the hygrometer.

Set the bag in a location where the temperature is fairly constant at room temp. After 8-12 hours check the reading of the hygrometer while still in the bag. It should read 75% relative humidity.If not, you know how much it is off so write it down and add/subtract from the reading.

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