False Bottom Diameter

[JohnK93]

Hey all,
I have a 10 gallon cylindrical cooler and I've replaced the spigot with a ball valve and internal barbed fitting. I was going to do a braided SS filter, but now I'm thinking to just suck it up and go with a domed false bottom. Seems easier and more effective. Anyway, I measured the bottom of the cooler to be about 12.5", so I could probably squeeze a 12" diameter bottom in, but with the barbed fitting in place it might be trick to maneuver into place.

So my question is, is there much of a difference between a 12" false bottom that would definitely cover the entire bottom and a 10" false bottom that will leave about an inch of the bottom exposed all round? I can't image there will be a noticeable difference. The prices are similar, so that's not really an issue, just the ability to get it passed the barbed fitting to remove and clean it.

Advice?

Thanks,
John

 

[pfgonzo]

I'm not an expert on water flow dynamics by any means, but my understanding is that a flat full-coverage false bottom is better if you're fly sparging, as a domed one that does not cover the width of the tun will (may?) result in some channeling.

If you're batch sparging, you're getting all the liquid out with each batch, so it doesn't really matter and a smaller dome is fine.

[edit] If it's not full-coverage, make sure it is domed, and actually touches the bottom of your mash tun around its perimeter. If it's not a dome shape, and raised up an inch or two on supports from the bottom of your tun, the grain will obviously just slide underneath.

[Edit 2] If you go the full-coverage route, flat or domed is fine. Just watch your mash consistency and liquid flow rate. People have reportedly destroyed their false bottoms when their sparges partially (or totally) stuck, and they kept pumping. The vacuum a march pump creates can be pretty powerful.

 

[JohnK93]

Thanks for the info. I'm going to be batch sparging and it will be a domed false bottom. I think I'm going to pick up a 12" at the LBS and see how that fits. They're sometimes more expensive, but it looks to be the same price as ordering it in this case.

John