Floating grain bed

[agentgonzo]

For ages I've had problems with the grain bed not compacting and floating up as the sparge liquor is added to the MT. This happened every time I brewed and I just got used to it.

I've just completed a brew and during the mash I managed to dislodge the grain filter so had to transfer all the mash out of the MT into another tun, re-fit the filter and then transfer the mash back to sparge. Amazingly, the grain bed didn't float up to the top of the water level as normal, but sat and compacted at the bottom with the proper inch of clear liquor on top of it.

I presume that what has happened before was that the tiny bubbles of air that come out of the water clung to the grain and caused it to float, but by transferring the mash twice, this bashed all the air off the grain husks and they no longer floated.

Has anyone else experienced this and should I vigorously stir the mash (and then let it settle obviously) before vorlautering to get a grain bed that sets in future?

[agentgonzo]

I'm fly sparging. I tried all kinds of things before and exactly the same happened. I tried it with a sparge time of 15 minutes (far too fast in my opinion) and it still happened. I don't think that it's adding too much water as (from what I've read) the level of the water should be 1/2 - 1 inch above the grain bed. The level of the water got to this level in the MT but then the grain started floating up to it.

This last time (with the grain transfers) I got up to about 1 and a half inches above the grain bed and the grain bed stayed steady and didn't budge at all.

[Graham]

I was always under the impression that the mash bed is supposed to float during fly-sparging. That is why one balances input flow and output flow, to keep the grain bed floating.

[Graham]

I don't under let but I do have to make sure the mash screen is pushed down after filling the MT as trapped air can often cause it to float.

I would guess that your home-made one does not float as well as the commercial plastic ones. My Phils Phalse bottom floats - full stop. I've had to put a hefty stainless, engineering nut and bolt in it to weigh it down.

I've just bought a plastic camping plate from Millett's, and that seems plenty heavy enough to stay on the bottom, but I haven't drilled any holes in it yet. It might be a different story then.

[agentgonzo]

I'm not sure what you mean by under letting.

My MT is a converted coolbox. I've got a manifold at the bottom made from 1/2" copper pipe, so that's definitely not buoyant and causing the grain to float. I've never been able to figure out why it does it when everyone else says that there's just sits there underneath the surface of the water. Hence why I asked you enlightened folk.

Although thinking about it some more... The copper manifold is a D shape that lies flat on the bottom of the MT. The bottom half of the pipe is slotted to act as the filter. This will mean that there's an air-lock in the top half of the pipe. As it's just pushed together and not watertight, this air will leak over the time of the mash and push its way up through the grain bed and stick to the grain husks, making them float. Does this sound reasonable? Presumably this air-that-got-stuck-to-the-grain got knocked off when I was transferring it last time and so it didn't float?

[Vossy1]

I've never known the grains to float on the water although they have a certain buoyancy

Just to add that I have had floating mashes. The grains rose to the top of the tun mid mash, and wouldn't go back down. There was no issue with the FB and another forum member was present when it happened.
It didn't effect efficiency so I just accept it when it happens

[prolix]

It happens some times the grains float high some times they sink, when they float high drain the wort a bit to slightly compact them then sparge from there, as DaaB said but just wetting the surface a mm or 2

[MARMITE]

Why not obtain some scrap stainless steel perforated 2mm plate from a stainless fabrication shop .If you ask them nicely they will weld 4 pegs to the bottom to keep the mesh above the tap .All you have to do then is to bend the edges over with pliers. in addition I got another small piece of scrap rolled it and stuffed it up the inside of the tap to form a second filter.This works brilliantly ,mash tun run-off is superb and you can control this by the tap.I dont bother to keep the grains floating and still get mash efficiencies of 85-95%.The plate cost me a tenner although I was wearing a short skirt at the time but thats another story ........

[des]

Called in at Roosters with Bandit a few months back and remember the gaffer (sean) telling us not to mix the mash too much otherwise it will not retain enough air pockets and sink!!!

[des]

I was wearing a short skirt at the time but thats another story ........

Piccies please

[oxford brewer]

The short skirt discount card might work for some people but I just get funny looks when I try it

Try putting the short skirt on Hector

[Graham]

Called in at Roosters with Bandit a few months back and remember the gaffer (sean) telling us not to mix the mash too much otherwise it will not retain enough air pockets and sink!!!

Tis true, if you stir the mash too much it will sink and probably cause a set mash - I've done that - been there!

[Graham]

Why not obtain some scrap stainless steel perforated 2mm plate from a stainless fabrication shop .If you ask them nicely they will weld 4 pegs to the bottom to keep the mesh above the tap .All you have to do then is to bend the edges over with pliers. in addition I got another small piece of scrap rolled it and stuffed it up the inside of the tap to form a second filter.This works brilliantly ,mash tun run-off is superb and you can control this by the tap.I dont bother to keep the grains floating and still get mash efficiencies of 85-95%.The plate cost me a tenner although I was wearing a short skirt at the time but thats another story ........

I've been looking, longingly, at the perforated stainless on the RS Components web site; wondering how the hell I would cut it into a perfect circle, and what with, if I bought some. I would use stainless nuts and bolts for the feet though - that's the easy bit.

[agentgonzo]

I did another brew last night, and half way through the mash, took the lid of the MT and gave the mash a good stir with the paddle. When I came to sparge, the mash settled to the bottom and didn't float up with the sparge water. I'm going to do this from now on. Seems to have fixed the floating mash problem.

[MARMITE]

You can cut stainless steel accurately using a 4 1/2 inch angle grinder with a NEW metal disc. Always use a new blade because a used one will transfer minute particles of mild steel from a previous job and cause rusting. You can use hardboard or similar as a template to form the shape you require and then mark it onto the stainless or clamp the hardboard to the stainless and cut round it. Small gaps are not a problem if you also use a rolled bit of stainless inserted into the outlet tap to form a second filter.I had thought of cutting a lengthways slot into a bit of syphon tube and using it to form a tight fit against the side of the drum. However I haven't got round to it yet because the present arrangement works really well.

PS I have done 60+ brews and never had a problem with floating grains.