Still air hatcher? or other ideas for higher humidity

[BeardedChick]

Does anyone use a still air hatcher? I thought about trying it. I'm having trouble keeping humidity up in my smaller hatcher 'bator. DH thinks it's because it's smaller volume-wise than my 'bator and ends up having too much air exchange (which depletes the humidity). My larger 'bator is much easier to maintain humidity in...

Keep in mind I'm in arid high altitude climate - everything dessicates up here because it's so dry (think Anasazi mummies). Also there is less O2 in the air, so I have to have enough air exchange to keep embryos from suffocating during hatch.

My water tray covers the bottom of the bator and it has sponges on it, but H still isn't staying up enough when I have the fan on.

The easy-to-test options for upping H that we thought of:

1. try still air hatching with all the air holes open

2. put in a jar of water and an aquarium bubble in the bator for air intake - this would humidify incoming air and it might move enough air so I don't need a fan

3. try to find a very low volume fan, my current fan is on a low voltage transformer, but it still moves a lot of air

Or worst case I will build myself a new hatcher - if I hadn't spent all my money on camera equip. this year, I'd give up and buy a Dickey!

 

[twigg]

Quote:
Still air hatchers aren't the easiest to operate, as you have found.

Here is the problem:

The hatcher is where you need the highest humidity. In a still air, the only air movement is by convection. It is regular, and works well in an incubator, but it is very slow.

Now water enters the air by evaporation. The closer the RH gets to 100%, the more difficult it is for water molecules to leave the surface. This problem is compounded in a still air, because there will form a layer of saturated air directly above the water surface, slowing evaporation to almost zero.

This layer of air needs to be moved away, and now you see where this is going .......

A fan blowing on the water is the single biggest improvement you can make to this situation. Increasing the surface area helps, but not as much.

 

[BeardedChick]

It currently has a 4" fan, but I think it's displacing too much air volume for the size of the 'bator & pulling in too much dry air.

DH said I could drill holes in the fan blades so it moves less air, but I'm not ready to do that quite yet...

 

[twigg]

Quote:
The hatcher needs some ventilation, but not too much. Try closing some holes.

If the 4" fan is 12V DC, you can slow it down by running it as low as 7.5V with no ill effects.

 

[BeardedChick]

Fan is a 12v running at 7.5.

I'm not sure how many air holes I can close. From what I've read, it's possible to get O2 saturation too low at high altitude (and embryos die in eggs).

Wish I had an instrument to measure 'bator O2 sat but they are expensive...

 

[twigg]

Quote:
You are over-thinking it.

If you can get the RH and temp stable in the right range you will probably have relatively few issues.

If you are sure they are right (calibrated thermometers and RH meter), and they don't hatch, then further investigation would be in order.

O2 sat would, I would think, be less of an issue that too much CO2

 

[BeardedChick]

Quote:
You are over-thinking it.

If you can get the RH and temp stable in the right range you will probably have relatively few issues.

If you are sure they are right (calibrated thermometers and RH meter), and they don't hatch, then further investigation would be in order.

O2 sat would, I would think, be less of an issue that too much CO2

From what I've read, at high altitude O2 sat is an issue esp. as altitude approaches 6,000' (I'm at 7,000')... Eggs produced at low altitude do not exchange O2 as well as eggs produced at high altitude so the problem is exacerbated w/ shipped eggs.

The problem I am having is too many eggs look great at the 18 day candling, and chicks are not getting through the membrane to pip.

I think it's either:
not enough humidity
not enough oxygen

or a combination of both

This last time I actually opened the bator and candled at day 23 (usually I leave the 'bator closed) and could see a few trying to get out of the membrane. Actually, when I saw them I thought they were through the membrane... However after they failed to hatch, I opened the eggs at day 25 and found they had not made it through the membrane. But I did see them trying.

So I want to make a change before the next small batch goes into the hatcher.

The other thing I read is that as humidity is increased, it displaces O2 out of the incubator... So that's another factor to consider at high altitude. We are already ~20% lower on O2 than sea level, then we're driving out more O2 with the increased humidity.

Maybe it's overthought, maybe not. I just want it to go better!

 

[BeardedChick]

Ok, got a smaller fan. Tore everything out of the 'bator completely... Moved the fan and light down and the rack that the eggs sit on up. The light is more directly heating the water pan and the fan is moving the warmed air across the water.

I closed up most of the holes.

The humidity is going up higher - into the 70's. That's a *lot* better.

Before I did all that I tried a bubbler for the air intake but the results weren't great... It didn't make humidity go up as fast as I thought it might.

However, now I can turn the bubbler so that the air intake is increased w/o diminishing the humidity. That will solve my worries about O2 sats in a closed up 'bator if I see any problems.

So Twigg, YOU WERE RIGHT!