Regulating incubator humidity in UK

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KittyKat

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The air in the house (around the incubator) currently has 60% humidity while outdoors, it is around 90-100% (daily fogs, pretty much solid walls of water, grass wet for the whole day even in full sun shine and so on).

When I first tested the fan-assisted incubator prior to starting the incubation, I got the following results (using warm water and letting the incubator settle for 24 hours each time):
* When I followed instructions and just dumped 100ml of water into the bottom of the incubator, the humidity registered as 85-90%
* When I tried the incubator "dry", it was 20-30%
* I tried the water in a variety of low surface area containers, working my way down to a bottle screw top, which gave me a range of 80-90%
* I finally set it up using a bottle screw top with a piece of polystyrene which covers most of the surface area, leaving only about 5mm² of surface area and this gives me 60-65%

My final result is smack in the middle of the recommendations in the instructions, but I have read that some people prefer to hatch at 40-50%. I am also slightly concerned that 60-65% is too low for hatching, but 85-90% is too high. I will try increasing the surface area slightly in the bottle screw top for hatching, but right now, I would appreciate any recommendations for improvement (or reassurances if we're getting it right).
 
My incubator instructions recommend the following for poultry:

During incubation 40-50% and at hatching 65% or more

I set the humidity at 45% for the first 18 days and then turn up the setting to 65% for hatching. I have good results following these instructions.
 
Many people find that they get the best hatch rate if they incubate dry in the UK, ie they add no water at all until the day when turning stops, at which point you can push up the humidity for the hatch. Personally I wouldn't want the humidity to go above 45-50%, and this is usually available from the ambient humidity level of the air around. More chicks die because they drown in shell in the early stages than from under-humidity. They do need high humidity to hatch but overdoing it early on means that the water vapour gets in through the porous shells and stops them being able to breathe.
 
I'm manually turning the eggs as the incubator was advertised to take 12 for automatic turning, but actually fits only 6 comfortably (I can squeeze in 9, but then the turning is very dodgy), so I can add a drop of water every time I turn. Opening the incubator up for turning also drop the humidity to 40% a few times per day. I will take the water out today, add a single drop of water and see what I get by morning. If that still gives me over 50%, then I'll go dry.

In theory, what effect does variations in humidity have on hatching eggs?
 
KittyKat said:
In theory, what effect does variations in humidity have on hatching eggs?
Click to expand...

Marigold's post gives you a good, clear explanation of the problems that occur if the humidity is too high during the first 17/18 days. If you have problems controlling the humidity of your incubator take Marigold's advice and dry incubate until the last 3 days. I would candle the eggs at about 10 days and remove any infertile eggs. At day 18 you must stop turning the eggs, raise the humidity, make sure the vent is partly open and don't open the incubator whilst the chicks are hatching.

Perhaps it would be a good idea to incubate less eggs so that the automatic turning mechanism works. If you don't have to keep opening the incubator to turn the eggs the humidity should remain constant.
 
The shell porosity will affect the required humidity KittyKat. What you are actually aiming to do is create an air sac in the first 18 days. Too dry and the sac is too big and the egg dries out. Too humid and there is not a big enough sac for them to manoeuvre for pipping. They need space to get their head out from under the wing to break the end of the egg open. The reason the egg stops turning after day 18 is to allow them to orientate themselves for this process. The humidity goes up so that the membrane is kept moist, otherwise they become glued to it as they pip. They have a very limited amount of energy for this process. So if they get stuck or get disorientated they die.

I would run 'dry' for 10 days and see how the air sac develops. The book 'Incubation- a guide to Hatching and Rearing' by Katie Thear shows you the air sac development on page 42. For pipping I would fill the incubator water container. It isn't an exact science and humidity gauges are very inaccurate anyway, despite the reading being to one decimal point. You need a good candling torch though.

As 3441sussex says, opening the incubator affects the humidity and it takes time to recover. Manual turning means it will never remain constant. In your case it will therefore be an average between 'dry' at 20-30% and the room at 60-65%, which is going to end up being around the 40% required.
 
I ended up taking the water out altogether on the second last turning yesterday and the humidity dropped to 40% within an hour and has stayed there since then. The reading was not affected by opening for turning last night or today. On the initial visual inspection, which I do realise is not particularly accurate, all the eggs appeared to have normal porosity with the exception of one which looked unusually porous. That is, assuming the photos that I found online were correct.

Is there any downside to candling a bit earlier, around day 7? If I find that I have only 6 infertile eggs, I can switch to automatic turning, you see… but there is one benefit to manual turning with this incubator: I can have the eggs sitting air sack up rather than lying flat.

I have ordered the book, which should be here on Tuesday.

So am I correct in understanding that any humidity variations average out in terms of the effect on the eggs in the earlier days of the incubation?
 
You can't do anything about shell porosity, expect realise that your one egg may develop a larger air sac than the others. Whether this has a detremental effect on the hatch remains to be seen.

We candle at day 6 KittyKat. In our case we load more eggs in and then deal with the double hatching and rearing process when it arises- which is complicated, so not worth going into detail here. It is a good idea to remove the infertile eggs at day 7 as you plan, but it is rather difficult to tell at that stage so you may not remove that many. You will be able to tell better by day 10. I don't know if you have counted the day you put the eggs in as day 0 or not, but day 1 starts 24 hours after they went in, so they are 1 day old. Just like people count their age in years.

Yes, I think the humidity averages out. One thing that occurred to me after my last post was that the eggs themselves are adding humidity with the evaporation of their water content. How much that is exactly I don't know, but in your case the figures suggest 10%.
 
I candled the day they arrived and 24 hours later right, before I put them in. I didn't see any abnormalities (except the one egg that looked very porous) and I am counting as day 0 on the day that they went in, which makes today day 3.

It finally rained last night and the humidity is now down to 35-39% (it remained at a steady 42% before).
 
Woke up this morning to see humidity at 59% and opened up the incubator to find an egg with a 5mm hole in it, leaking white everywhere. It managed to roll into the way of the automatic turner mechanism during the night. It was one that I candled last night on last turning and thought that I saw an embryo. Suffice to say as it seemed damaged beyond repair as the shell and the membraine were damaged (please correct me if I'm wrong), I cracked it open and found a 1 cm healthy embryo inside. Really kicking myself for not securing it better. Other than that, the humidity has been around 35-45%, depending on the weather.

The only good outcome from this is that all the eggs that have candled over the last few days have shown the same sign of an embryo, so I feel quite relieved that at least something is happening. None of the eggs look bad yet.
 
To summarise the humidity started off at 80% on day 0, 65% on day 1, 42% on day 2 and then dropped gradually to 29% on day 18. Today is day18, so I added extra water and the humidity is now at 60% for hatching.There has been an average of a 10% decrease in the weight of the eggs from day 0 to day 18. 5 eggs look good for hatching, 3 eggs appear to be quitters and 4 had been damaged or quit a while ago.
 
I've had trouble maintaining the humidity at exactly 70-75%, so it's been bouncing more like between 65 and 80%. The good news is that the first chick pipped at 9:30 this morning. It (or maybe also some of the others as well) are squeaking non-stop and it has been very aggressive at sticking its beak out of the shell.
 
One has hatched and two more have pipped. The tumbling around the incubator while trying to find its legs is quite adorable!
 
Hi
Sorry but ive had trouble keeping the humidity most of the time it has be 39% to 43%. I am manually turning the eggs i have candled at 18 days 3 show no sign of anything just cloudy eggs. 1 shows i think a part formed embryo. the other 2 show the embroils had filled the eggs bar the reasonably sized air sack. Put the humidity up to 75% on day 18 however had a falce reading due to the sensor being faulty added another Hydrometer and found it was only reading 50% humidity. Have got the humidity up to 75% with 2 hydrometers however im on day 20 and nothing is happening have i lost my 2 remaining embryos. the problem is my hatching eggs take 2 days in the post and not 1 is this my biggest problem as this is my 3rd attempt at hatching eggs.
 
Three are out now, fourth is about to start zipping. Once the first one hatched, humidity shot up to 95% and it took over 9 hours to dry. My first started hatching on the morning of day 21, second and thrid in the afternoon and fourth in the morning of day 22. Apparently they can take up to 25 days to start hatching. From what I understand, day 20 hatches are ones which have been set too hot.
 
Thanks KittyKat
So all is not lost yet! Am so pleased your hatch is turning out to be a success. Congrats
 
Early hatches are slightly too hot KittyKat, as you say. Late ones are too cold, or a midway power cut. Humidity soars for a while as the chick and shell dries out.

Jan, the humidity is very important as they pip, that is break the egg shell. I don't think you should give up yet. Your biggest problems may be ahead with hatching this time of year. Hydrometers are not that accurate and I don't bother. Just add another water tray at day 18. The humidity depends on the evaporating surface area and the fan, so it's something you just get a feel for with your unit. We didn't respond fast enough to a change in ambient humidity last year. The air sac didn't develop enough on two and they couldn't manoeuvre to pip, so died in the shell.
 
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