How do I know if this hydrometer is working properly?

[Dr Evy]

Hi all,
So I’m planning on hatching more eggs soon, this will be my second time. The first time I hatched eggs I don’t know if my hydrometer was working properly the whole time. The reading it gave me just didn’t make sense. I only had like 3 tablespoons of water in the incubator until lockdown and it would always tell me it was at like 72% humidity. It fluctuated a lot too. Like sometimes when I woke up it would be at 40, then when I added water it would shoot back up to 80. At first I had tried to put a half a cup of water in there but it went up to 99% so then I emailed the people I got the incubator from and the email back told me 2.5-3 tablespoons of water till lockdown then around 3.5 for lockdown. So I did that and my chicks hatched fine.. I’m confused at why it would always say the humidity was so high. Is that normal?
Also just another question, is it normal that I had to add water to the incubator twice a day to keep it at the right humidity? Even in lockdown I had to open it and add water a lot. It’s a forced air incubator. There’s pictures of the incubator and the hydrometer below.

 

[Egghead_Jr]

That's not a normal incubating humidity. The hygrometer is likely reading high. Your teaspoons of water method seems to work. Humidity in an incubator is a function of surface area. How that incubators water troughs work I'm not familiar so can't comment.

To calibrate your hygrometer perform a salt test:

Fill a milk, juice, water cap with salt and add drops of water until salt is saturated. Like wet sand.

Put the hygrometer and cap of salt into a sealed container. Zip lock sandwich bag works.

Throw it on your kitchen counter and wait until morning. The reading should be exactly 75% RH.

How ever far off your hygrometer is reading from 75 is the calibration. Some can be adjusted most we just know to add or subtract the calibration number to know actual humidity.

 

[Dr Evy]

That's not a normal incubating humidity. The hygrometer is likely reading high. Your teaspoons of water method seems to work. Humidity in an incubator is a function of surface area. How that incubators water troughs work I'm not familiar so can't comment.

To calibrate your hygrometer perform a salt test:

Fill a milk, juice, water cap with salt and add drops of water until salt is saturated. Like wet sand.

Put the hygrometer and cap of salt into a sealed container. Zip lock sandwich bag works.

Throw it on your kitchen counter and wait until morning. The reading should be exactly 75% RH.

How ever far off your hygrometer is reading from 75 is the calibration. Some can be adjusted most we just know to add or subtract the calibration number to know actual humidity.

Ok thanks so much, I’ll do that when I get home.

 

[cmom]

I have some thermometers like the one in your picture. They are not the most accurate but the one in your picture, your temperature is way low. It should read 35ºC not 26.7ºC. You may want to invest in another thermometer/hygrometer. I keep my humidity around 35% during incubation because the eggs need to loose some moisture. When I put the eggs in the hatcher I get it up to around 75%.

 

[Dr Evy]

I have some thermometers like the one in your picture. They are not the most accurate but the one in your picture, your temperature is way low. It should read 35ºC not 26.7ºC. You may want to invest in another thermometer/hygrometer. I keep my humidity around 35% during incubation because the eggs need to loose some moisture. When I put the eggs in the hatcher I get it up to around 75%.

Thanks. Yeah I forgot to mention that’s another way I knew it wasn’t accurate when it was in the incubator. Don’t worry I’m not hatching any right now so it was just reading room temperature. I might invest in one before I hatch again.

 

[Dr Evy]

I didn’t have a juice cap so I just used a spoon? Will that work? In the morning it will read 75%?

 

[Egghead_Jr]

Correct. Whatever the difference is is your calibration. The hygrometer works it's just reading wrong and will consistently be that far off. So if it's telling you 85% in morning you'll always deduct 10 from it's reading for correct RH.

BTW- I provide small pillow of air in the bag. You want to ensure the holes in hygrometer are not covered by plastic so it reads the air humidity in the bag.

 

[Mellowmalt]

I had that hydrometer once but never got any reliable readings from it. It is absolute rubbish so as to your question whether it is normal, yes completely. You'd be better off drawing a dial on a piece of paper and trust that "reading" over that.

You want to get yourself either a chicktech or a govee thermometer, they will give you a reliable reading, anything else and you'll be buying twice!

 

[Dr Evy]

I had that hydrometer once but never got any reliable readings from it. It is absolute rubbish so as to your question whether it is normal, yes completely. You'd be better off drawing a dial on a piece of paper and trust that "reading" over that.

You want to get yourself either a chicktech or a govee thermometer, they will give you a reliable reading, anything else and you'll be buying twice!

Ok thanks so much! Do you know where I can buy one of the ones you suggested?

 

[AntiqueB]

I have a similar incubator. I used a Govee, which I calibrated using a very old, very reliable analog one. Meat thermometers are also pretty reliable for temperatures.

While incubating, I usually added water twice a day, between 5-10 ml each time. I put in a little more (maybe 15-20 ml) for lockdown, and it was fine. So you were correct, and their directions are way, way off.