Mash efficiency vs. wort collection

[green_giant43]

Having what I consider some weird issues. The basic issue is that I seem to be getting good efficiency but start running into issues with not getting enough pre-boil volume. I am doing all grain and I fly sparge and here's the scenarios over two batches:

1) First was an amber clone of a local brew. I don't know how Beersmith gets its calculations for mash efficiency so I did all the work longhand and got 89.7% mash efficiency. I just barely got the wort volume I needed for pre-boil though as my refractometer (calibrated) was giving me 1.008 at the end (where I cut it off for fear of extracting tannins.) This was my first all grain batch so I ended up fly sparging way too quickly and it was done in about 20 mins by my estimations. Sparge water was around 180 I believe.

2) Second batch was a session IPA I designed. This is where it gets tricky- I tried to slow up my fly sparge to the rate of 1 gallon/10 minutes (full preboil volume after about an hour sounded right as a normal fly sparge is supposed to take around 60-90 minutes right?) This was fine for a bit but the gravity kept falling and falling rapidly (sparge water was a bit hot too at around 195 and I didn't check it before I started stupidly enough to get an exact temp- this is more of a problem of verifying my heat loss out of that cooler than anything.) Anyway, it falls so much I started sparging quicker and I hit 1.009 at 5.5 gallons of wort (1.25 short of preboil.) I added a gallon of water, went for a vigorous boil, overshot my target OG just slightly and ended up with 5.5 gallons post boil wort (what I figured I'd get after adjusting on the fly.) Ended up with 83.9% mash efficiency doing the calculations for grains with 5.5 gallons of wort collected.

So where I'm at is this- should I be concerned that while I hit my mash efficiency I am falling short on wort collection? I'd rather not end up short and then have to add just a gallon or more of water to get pre-boil volume (nor do I think that should be necessary if I'm doing things right.) I do wonder if this might be associated with pH as I have not delved into that yet. I know that my water is basically good but I haven't been able to invest in a pH meter yet (nor have I tried any of the 5.2 methods or anything as I know well enough that it's a balance and there's no real one fits all solution from what I've gathered.) I am looking into getting a water report for my local water. Could my pH be negatively affecting my readings towards the end of my sparges causing it to have lower sugar content in the last runnings?

I know that was extremely long but I figured the more info I provided the better advice I'd get in return.

 

[Bobby_M]

What do you have installed, a braid, bazooka tube, manifold, or false bottom? If your lauter efficiency is correct at near 90%, there's no harm in topping up your boil with water. Take a look at the colorpHast 4-7 test strips. Accurate enough for this purpose and about $20 for 200 tests.

 

[green_giant43]

What do you have installed, a braid, bazooka tube, manifold, or false bottom? If your lauter efficiency is correct at near 90%, there's no harm in topping up your boil with water. Take a look at the colorpHast 4-7 test strips. Accurate enough for this purpose and about $20 for 200 tests.

True false bottom. I'm using the fermenter favorite cooler combo from Northern Brewer that I got a good deal on (2 coolers, one has a false bottom and the other I use for sparging.)

So am I just getting most of the sugars out in the first part of my sparge then which results in my low sugar output near the end?

Also, to that end, what can I do to get above my total efficiency that's sitting around the 70% mark on average?

Thanks for the tip on the strips. I've read that they can be good, might not be good but for $20 it's worth a shot.