The Hot Spot

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Originally Posted by kitedemon

I have 4 inch and I just used a ir gun to see how large the hot spot was. At 1 inch increments from the back. It is a reasonably accurate gun better than many not 100%.

87º
88º
90º
91º
91º
90º
88º
87º
84º
81º
80º for the rest basically 79º at the very front.

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Interesting, do you have that slightly cooler couple inches at the back because the heat tape isn't directly at the back of the tub? I see some people who have their heat tape right at the back of the shelves, the corner of the tub exactly matching the heat tape. There are others who have heat tape layed so that it runs across the bottom of the tub a little bit further up the tub length.

How many inches in from the back of a 28 or 32 qt tub would you lay your 4" heat tape? Not from the shelve as that depends how far your push the tub in, but from the back of the bottom of the tub after you push it in. From your numbers I am guessing 2 - 3 inches, depending on whether the first figure is the back or your first 1" increment FROM the back.

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Originally Posted by Don

EDIT: the Freedom Breeder uses 5". I use 6" panels on my ARS racks.

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Oh right, I didn't catch that. 5" were for the freedom breeders. I only looked through the ARS ones because that is my "dream" rack I wish I had! LOL.

On a 41 qt rack, my heat panel starts about four inches from the back of the tub. On my RBI and HE racks (which are 32 qt) the heat tape is also about four inches from the back of the tub. So, yes, the heat tape is not aligned with the very back of the tub, but brought inward.

Don, I just measured it. It is about 3 and a half inches. The temps were from inside the tub. (I have a hatch for cleaning the rack body it didn't help much but it is still there.) The tub stands off the back wall about an inch slightly less. I also am using rubbermaid tubs so they have 'runner' on the bottom and it makes an air pocket that is static (closed in air doesn't circulate under the tub) if that allows the temp to spread some I am unsure. That would be my guess. The other thing I have is 17inch low wattage flexwatt for heating the front of tubs. The rack is located in a cool room and it is well insulated and mods to change the way air circulates to help keep heat. That also may have some effect but ambient temps and surface may or may not have monster effects on each other.

Solid body rack too. The vents are about 1 inch up on the back wall from the shelf.

All my racks have 4 inch heat tape running through them, while I keep the hatchlings hotspot considerably lower because it is difficult to have a gradient in a tub as small a 6 quarts all my adults who are in 32 quarts and 41 quarts are kept around 88 degrees.

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Originally Posted by Deborah

All my racks have 4 inch heat tape running through them, while I keep the hatchlings hotspot considerably lower because it is difficult to have a gradient in a tub as small a 6 quarts all my adults who are in 32 quarts and 41 quarts are kept around 88 degrees.

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Deborah, that is a good point about hatchlings. My 6qt hatchling racks all have back heat instead of belly because the tubs are so small and the need for a heat gradient.

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Originally Posted by hungba

That's my logic too (see my other post). But people seem to be using 4" for bigger tubs without problems. I talked to a breeder here the other day and I brought up the 11" for bigger tub he actually advised against it. I was asking about 32 quart sized tubs thought, but still 4 inches doesn't cover 1/3 of that. I also see Ralph Davis videos where his freedom breeders and ARS racks with adult tubs only use 3 inches. It obviously works, but it doesn't make sense to me that people recommend 1/3 and at the same time use 4" for everything hatchling to adult tubs... I don't understand it.

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doesnt make sense to me either.
I've used 11" with great results and my bps I find are not as picky eaters as they used to be. I'm in ND and our temps are not always high, so maybe its a climate thing but I wouldnt use anything but 11".
I suppose to each his own. Depends on your situation and what works for you.