We’ve all made the “not enough sparge water” mistake. You can never have too much sparge water. And the extra hot water can be used for cleaning anyway.

Yes, grains in the kettle can DEFINITELY cause astringency, which you can perceive as “dryness in the mouthfeel.” It’s a little like sucking on a teabag, right? That is astringency, and is a result of (among other things) tannins being extracted from the grains due to the grain being at too high a temperature (especially when also at too high a pH, but the temp is the real problem here).

One low-tech way you can alleviate this problem is to collect your wort into another vessel – a bucket, another kettle, whatever. Then, let it settle for a little while (10 minutes? a half hour? not too much more than that) and rack off into your actual kettle you’re going to boil in.

Or, get a different false bottom. Personally, I batch sparge and I use a Bazooka screen. I used to use the Listermann false bottom in a picnic cooler, that worked OK but the false bottom could float and grain could get underneath it (causing your very problem). There are probably 10 different commercial false bottoms out there, and 100 homemade ones.

What are you currently using as your false bottom? What size/shape is your mash tun?

No, I understand that your mash temp is OK. But you’re letting some grains get into the boil kettle, which obviously gets to a higher temperature. You really don’t want to let grain get to above 170°F (maybe a bit higher depending on pH and other stuff), or it will extract some tannins.

I used one of those orange cooler systems for a year or so, and I tended to have your same problem of the floating false bottom.

I would think you could probably add a stainless or brass coupling and nipple (huh huh, he said nipple) or something to the top of the false bottom, and then attach the hose barb elbow to that. But that’s kind of a kludge and would probably cause other unforseen problems.

Really what I would recommend is to switch to batch sparging. There are arguments both ways, but I have switched entirely to batch sparging and I will never go back to fly sparging, I think batch is easier and quicker and no less efficient on my system. Check out this:
http://hbd.org/cascade/dennybrew/
However, instead of his toilet screen dealie, I would get one of these:
http://www.northernbrewer.com/brewing/mash-boil-screen.html

I think they make similar screens that will fit the 10-gal coolers like you have, like a “t-screen” or similar. Google for “homebrew mash cooler conversion” and I’m sure you’ll get some ideas that would work for your current equipment.

I use Beersmith to calculate stuff and make recipes (if you don’t have software, I’d recommend Beersmith, though there are other equally good choices out there).

The amounts of water should be the same between batch and fly.

To batch sparge, you recirc till clear and then crack it wide open to let it drain to your boil kettle. Then add the sparge water to the mash tun, stir it up well, after stirring I wait 5 minutes again though that really shouldn’t be necessary, recirc again, and crack it wide open to drain to the boil kettle.

With fly sparging the point is to adjust your flowrate to even out your inflow and outflow and end up with a full kettle about 60 minutes later. With batch sparging there’s no flowrate adjusting. While it can take a few minutes to do a recirc, I find that it takes me probably 20-30 minutes to fully sparge my grains and fill my kettle.

A perfect fly sparge is slightly more efficient (a few percent, equivalent to an extra half or 3/4 pound of malt) than a perfect batch sparge at getting the max amount of sugars out of the grain. However, it’s muuuuuch easier to do a perfect batch sparge (it’s pretty hard to do an imperfect batch sparge, actually) than it is to do a perfect, slow, even, fly sparge with no channelling/short circuiting. There can’t be channelling/short circuiting in a batch sparge, there usually is some in a fly sparge.

Your results may vary, but I will never go back to fly sparging again. I’m batch all the way.

Oooh, one thing I should have made clearer before, the mash boil screen won’t work correctly if you fly sparge. Well, it’ll work just fine, but you’ll have really bad efficiency, because there would be large volumes of the mash that wouldn’t have flow of sparge water.

That’s not an issue with batch, because the stirring makes the whole mash into basically one homogeneous volume.

But anyway, if you’re a masochist and end up deciding you like fly sparging better, you could use that screen in your boil kettle or probably somewhere else anyway, so it wouldn’t be a total waste. And it’s not like it’s super-expensive.