# Incubator and humidity



## shannonswyatt (May 7, 2012)

I see numbers all over the place on the proper humidity for finishing queens, from as low as 40% to as high as 70%. Can someone that regularly finishes queens in an incubator weigh in on the numbers they use for humidity? 

I was looking for an inexpensive incubator on Craigslist and someone advertised one as a chicken egg incubator. I got there and it was a lab quality incubator with an internal volume larger than a mini-fridge. I tested it out de-crystallizing some honey to see how well it held temperature. It stays spot on, but I need to do something for humidity. 

So far I have been using water in a pan which seems fine, but I would love to get an idea on what is the correct amount of moisture. Also is air movement necessary? It has a 110 outlet inside the unit so I can easily put a fan in it, but when I move the probe around to different spots the temps seem to stay the same. I'm guessing a little air movement would be beneficial, but it will probably raise the humidity.

I'm using an inexpensive thermometer and humidity gauge to monitor the levels remotely. I'm suspicious of the validity of the temperature and humidity on a cheap unit from Lowes, but the temps seem about the same as the temperature in the incubator. If someone has a recommendation on a cheap acurate humidity gauge I would love it.


----------



## AAIndigo (Jun 14, 2015)

I cut down a sponge and use it. Not sure what the best humidity level should be but my cheap gauge states 58% here. I have used this incubator 4 times this year and almost all cells have hatched so?


----------



## Oldtimer (Jul 4, 2010)

To find this out, I installed a high quality humidity sensor in the mid brood nest of a good strong hive. The surprising thing was that humidity would change quite a bit, along with the outside humidity. So the relative humidity (RH) in the hive was always between 50 and 80. 

Thing with that, the outside RH could be higher than the in hive RH, because the inside hive temperature was higher. RH is a percentage of how much water air can hold at a given temperature. So the amount of water in the air needed to achieve 100% saturation at say, 70 degrees, is less than 100% at 80 degrees, because air at 80 degrees can hold more water at 100% saturation. RH is Relative Humidity to 100%, at any given temperature. (hope all that makes sense).


So to the practical application in the incubator, I imitated the in broodnest conditions, and allowed humidity to fluctuate between 50% and 80% RH, but generally held it mid range at 60% or 70% RH. This was possible even when outside humidity was up to 95% RH, because the temperature in the incubator was higher, giving a lower RH for the same amount of water in the air.

I experimented with higher and lower humidity. Running RH in the incubator at 95% RH, the queens emerged with distended abdomens. They actually looked like nice big queens, but it was really water, and after a few hours they would excrete and shrink. So I decided this was probably not good for them. Humidity under 50% RH had the reverse effect, the queens emerged shrunken, which is probably also not good for them. 

So end of day, 60% to 70% RH seemed to be the ideal, and is also the main area that humidity sits in an actual hive brood nest.


As to air movement, yes. If there is no air movement, there can be warmer air near the top and I found that by placing high quality sensors around the incubator. Only very slight air movement is needed, I achieved it in my incubator with a computer fan. 


To create humidity, it is easy to overdo it. So I had a glass of water in the bottom of the incubator, with a computer fan pointing at it. If humidity went under 50% RH the fan came on, humidity would climb a few points then the fan would go off. I started out using a pan of water, but the large surface area made humidity go too high even when the fan was not on. So I changed to a glass, and the small surface area meant humidity only went up noticeably when the fan pointed at it was on.

Other thing, beware cheap humidity sensors. I have trialed quite a few, and found that the majority are not accurate. It is also hard to verify if they are accurate or not. So my suggestion would be test your humidity sensor in an actual hive, upper mid brood nest. Let it run a few days to get an average, then put the sensor in your incubator and set it the same as whatever the hive was. Do not be afraid to experiment, queen cells tolerate quite a wide variance in humidity, unlike temperature, where the ideal range is fairly narrow.


----------



## shannonswyatt (May 7, 2012)

Thanks!


----------



## Scott Gough (Dec 10, 2015)

That is great information Oldtimer. Thanks for taking the time to reply!


----------



## tarheit (Mar 26, 2003)

Excellent information. I've never found a good resource as to the 'right' humidity.

I generally figured that higher was better, but probably should be limited to around 60% because in a hive, too high humidity interfears with curing honey, and humidity over 60% can increase mold and mildew groth. It's good to see somethig a bit more practical than my guess.


----------



## little_john (Aug 4, 2014)

.
Very useful information in that post, Oldtimer - thanks.



Oldtimer said:


> Other thing, beware cheap humidity sensors. I have trialed quite a few, and found that the majority are not accurate. It is also hard to verify if they are accurate or not.


Should anyone want to calibrate a humidity sensor, then suggest you make-up several saturated-salt solutions - at least three - the sensor readings obtained from well-established standard humidity levels can then be used to draw a calibration graph.

Easy enough to do - just place an amount of each salt with distilled water into a jam jar, ensuring that there is always an excess of salt - i.e. some of that salt never gets to dissolve. Then the sensor is placed into the jar - ensuring that physical contact with the solution is avoided - and the reading taken. I'd suggest inserting the sensor through a spare lid, so the 'solution lid' can then be removed, with the 'sensor-lid' quickly replacing it. Then wait a short time for the sensor readings to stabilise before recording that reading.

So, which salts to use ?

Sodium Chloride (common table salt) is the #1 favourite of course, cheap and easy to obtain - and it saturates at 75% over the full 'domestic' temperature range (i.e. from 10 to 35 deg C ; 50 to 95 deg F) A very useful salt. 200g of this salt in 60ml of water will give you a saturated solution - so use a tad more salt or a tad less water than that to ensure the solution is fully saturated.

For a lower reading, Sodium Bromide will saturate at 55-62% over the above temperature range, with 57.6% being 'the standard' at 25 deg C. (I'll post the appropriate tables if anybody needs them) 200g of this salt in 80ml of water gives a sat. solution.

For an upper reading, Potassium Chloride will saturate at 83-86% over the above temperature range, with 84.3% being 'the standard' at 25 deg C. Again, 200g in 80ml of water.

There are plenty more salts which can be used, but the above 3 will cover the range of interest. The process of calibration may be a bit of a hassle perhaps, but is much better than simply guessing and hoping for the best, and you only need to do this once for each sensor. The saturated salt solutions themselves can always be stored away somewhere safe, for potential re-use at a later date. They won't 'go off' in the meanwhile !

LJ


----------

