Proportion of surface area in a fermentation vessel

I'm going to try fermenting in a rectangular shaped PE tank sort of like this
I will be spin welding all of the fittings myself and have the option of where the install them. My question is, given the choice, would I be better of standing the tank up, so as to reduce surface area of the fermenting wort, or would it be just as well to lay it down to easily facilitate a gravity flow system?

Also, in a large fermenter, would it be a good idea to purge the tank with CO2 before racking?

When racking cooled wort to a primary, you want it to be oxygenated, so CO2 would be counter productive or useless at best. Once fermentation begins, subsequent rackings will warrant CO2 purges in the target vessel.

As for orientation? IDK.

olllllo said:

When racking cooled wort to a primary, you want it to be oxygenated, so CO2 would be counter productive or useless at best. Once fermentation begins, subsequent rackings will warrant CO2 purges in the target vessel.

As for orientation? IDK.

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Good point... I was concerned over the potential for contamination with a lot of extra air/surface area. I guess it would be an O2 purge that may work... but is it necessary?

Are those significantly cheaper than the plastic conicals?

40 gallon for $190

http://www.plastic-mart.com/class.php?item=137

Bobby_M said:

Are those significantly cheaper than the plastic conicals?

40 gallon for $190

http://www.plastic-mart.com/class.php?item=137

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When you can buy them at wholesale with free shipping they are.

5isnotenough said:

When you can buy them at wholesale with free shipping they are.

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Can I have one?

You can lay it either way. Fermenters tend to be vertical because floor space is more expensive than height.