BeerBorg

Loves me some Belgian pale malt.
Doesn't love me its low efficiency.

Belgian pale malt has Low D -- '60' diastatic power ... much lower than the 100+ found in other pales.
It's high enough to 'self-convert' but wondering: Why its D-power be so low?

Not been getting typical brewhouse conversion with the Castle malt.
Does l-o-n-g mash improve brewhouse efficiency?
What mash temp / thickness for max extraction?

Maybe just mash a little mo' malt -- RDWHAHB -- and enjoy the ride?

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I'll hang up and take my answer offline.

It's undermodified and kilned a little bit differently then modern malts, both which take away some of the D. But that is also what gives it the nice flavors you crave. So like Munich, it will take longer to self-convert on its own. You have to get the mash PH in the right range and just be patient. IE do a 90 minute mash. An actual iodine test is in order if your not sure.

Or else, the easy answer for a single infusion mash is to mix it with some highly modified modern pilsner. A mix of say 40% Pilsner and 60% Belgian Pale will convert much more efficiently and still give you really nice results. Most recipes that call for Belgian Pale will mix it with Pilsner anyways, it's a very common combo. This is a good thing to do with any undermodified or more highly kilned (like Munich) malt.

Another option is just to throw some amylase enzyme into the mash. It's cheap to buy and will kick up the effective D power tremendously. It will deactivate when you boil it, so it won't wreck the beer.

Thanks for your helpful comments.
I too thought under-modified; however ... Castle's web site claims their pale malt is well-modified -- more so than their pils.

Mash times are typically 75' - 85' @ ~148 - 152°F
Double-batch sparge the grain bed having temps in the upper-160s.
Good volumes into the boil kettle and fermentor, i.e., some slack but nothing excessive.

It's not as if brewhouse efficiency is horrible; just not as good as other base malts with higher D-power.
Might have to try the amylase enzyme.

If it's not undermodifed it's the kilning which is why I mentioned that. Kilning has an effect on the D-Power that is left when it's done. Munich starts off as a malt that would have 100+ power but because of the kilning it ends up in the 60s and just able to self convert on its own. Dark Munich might be more in the 40s sometimes even.

But kilning is what brings about flavor too, so you win some and you lose some.