I've never heard of root rot in properly-made Gritty. Maybe you water too often? It's almost impossible to waterlog Gritty. What types of succulents are you having difficulty with? Is your indoor environment extremely humid?

How large is the bark you're using?

If the small particles fall to the bottom of the container, while the bark stays atop, there will be a lot of moisture in the lower layers.

Josh

Why not to leave bark out altogether?

Besides what Josh already mentioned, what size is everything screened to?
As Oxboy said, maybe it's in too humid of environment?
Unless they are left 'sitting' in water (if you after watering leave whatever drains out in the saucer & pot sitting in it), it shouldn't be waterlogged.

What succs do you grow?

Every environment is different. No one size fits all. As we see time and again on this forum. Maybe add perlite to increase drainage or more bark, or both. Also try using clay pots, plastic stays wet too long and does not breath.

Drew, perhaps you're unaware that these recipes are "starting points," meant to be adjusted to local gardening requirements. As such, the recipes were never intended to be one-size fits all. The principles behind the mixes are more important than the ingredients themselves.

One key principle is uniformity of particle size. Time and time again on this forum we see folks using bark that is too large. That's not a problem with the mix - that's a problem with the preparation of the mix.

Josh

If I had a dollar for every Drew vs. Josh or Drew vs. Al exchange...

I wish I were gettin' paid for it, too, Oxboy ;-)
Bad information has to be countered with good information.

Josh

Thanks, all! I appreciate all of the thoughtful responses.

I live near the Castro in San Francisco, so our indoor environment is foggy-humid, not extremely humid, but hardly ever dry... My planters are all clay, and sitting up above their water trays on marbles or bottle caps. I sift my mix using a few screens, and I included a photo to show you.

The succulents that I'm having difficulty with are all rescues of dubious background. So that may be it, really. They may have had such a rough life already that it'll end up being "failure to thrive" no matter what I do.

I know that there are ways to alter the mix, and if these are fussy succulents, I thought I'd help by giving them a less water-retentive home. Al recommended 3:4:2 for my Norfolk Pine, so I thought I'd go with 2:2:3 for some of my succulents... I just thought I'd ask you guys first.

Cheers!
Mary