10 gallon cylindrical Rubbermaid cooler with strainer bag?

Hi All,

I think DeathBrewer may have beaten me to this idea, but I can't find the thread. If I had a sufficiently large strainer bag, could I fit it inside a cylindrical 10 gallon Rubbermaid cooler, and use it with the stock dispensing valve for mashing? This seems like an easy way to get into cooler mashing, with no brass hardware (read: expensive). I foresee channeling as an issue with fly sparging, but maybe it's no biggie with, say, a double/triple batch sparge?

I like the rubbermaid due to large amount of insulation as well as the screw-on lid.

Advantages/disadvantages? How much grain do you suppose I could mash in a 10 gallon cylindrical cooler? I've tried using the "can I mash it?" calculator with little success in the past--the mash took much more room than originally expected.

Thanks for the input!
jkpq45

You might be onto something, but one problem that I can think of is you might have a some stuck sparge issues with that setup. If you could raise the bag slightly while sparging, that might solve that problem though. Give it a shot!

To add to the idea, a 5 gallon paint strainer bag would suspend the grain bed a-la-false bottom. You'd have to mash pretty thin to submerge th grains though.

Anything you could put in the bottom to help leave some kind of drain space would be good. I've seen people use those expandable veggie steamer trays before. You certainly don't want the grain bag to be able to touch the spigot outlet. It will clog it pretty easily.

Expense? Really? I'd guess around $10-15 from Lowes. Checkout this post.

I would recommend reading the thread and upgrading to 1/2" for the future.

I would fashion a basic cooler mash tun before I tried a grain bag in a 10 gal. round cooler, just my opinion.
Rectangular coolers are dirt cheap, easy to stir the grist, and work well for batch sparging. Link below shows an extremely basic, yet highly functional method to convert just about any cooler. Oh, and w/ an unconverted beverage cooler, you will have to depress the button valve while draining the tun...this may take a while and be a PITA!

Simple All Grain Brewing - German Pilsner

Yeah, either a veggie strainer or a wok steamer rack. Both will act like a false bottom, keeping the mesh from clogging up against the outlet port.

You will need to figure out some way to keep the button on the spigot depressed, though. You are not going to want to sit there holding it for that long, your thumb will fall off! For that alone, it would be worth it for me to get the brass hardware needed to set it up properly.

If you are going to use a bag why not just do a BIAB ? One keggle no valves

+1 Follow the directions just like BIAB.

Heat ALL your water, put that in the cooler with the bag already attached. Stir your grains in, cover, then mash away. When time is up, lift the bag up to drain, twisting the bag tight. Put the bag in a bucket over a colander or hang it over a bucket. The valve will get hot on the cooler so either pick it up and dump it or use a bottle cap and elastic to keep it open draining into your pot. Push down on the grain bag or squeeze if hanging then dump that liquid into your pot.

This is exactly how I brew. I've got about 10 batches under my belt with this approach, although I do use a 5 gallon igloo and not a 10. Pics follow:


I use a bag from the LHBS, I think its somewhere in the vicinity of 24x38. Big, fine mesh, and sturdy with a drawstring. The spigot is from a bottling bucket, we used a holesaw to get the opening wide enough, but that was the only modification we did to the cooler. The spigot is perfect for attaching racking tubing so your sparge doesn't splash into the kettle.


We don't use anything on the bottom like a collander, we just let the bag sit. The grains create their own bed, and the flow is pretty good. If anything gets slow or stuck, just pull up on the bag a little and it starts up again. A few vorlaufs and it should run clean as a whistle.


We get 70% eff pretty consistantly, as long as we hit our mash temps (the cooler is extreamly good at keeping temp) and washing the bag is easy.

10 gallons is pretty big, but the size of the bag I have should make it. Essentially the bag serves simply as a sparging device, this isn't a BIAB technique or anything. We batch sparge and mash out as usual.

Or if you don't want to go through the trouble of switching the spigot out, this always works