You could try using NAPA floor dry. It will not float like perlite does. My plants love it better than the coco. I have my best roots in the top 2 inches of my pot where I top dress with the floor dry. Cost me about $7 a bag and the bag is 6 gallon.
No. NO. NOOOOOOO....
I admit I used to advocate this - but I think there are better solutions and products to use at the end of the day. I've explained my reasoning behind this in several posts, but the calcined diatomaceous earth (such as in some kitty litters and oil spill products) is primarily designed to be an ABSORBENT.
Yes, it creates a good particle sized spacing within the medium - HOWEVER, as much as it can facilitate drainage it also promotes retention.
I found my soil become TOO compact and found that my soil would dry out unevenly - with the sides getting dry and pulling away from the containers, yet the middle near root stock staying moist. This resulted in poor root health where things were too dry and too wet at the same time. Not to mention, calcined DE has a rather high pH...
On top of those issues, I always found myself getting a strange "deficiency" or spotting on my leaves that I could not ever diagnose 100% accurately. This would completely disappear in soils that were not utilizing the calcined type products...
I honestly wish I had NEVER promoted the product to be used / tried out by other people - because now I have to constantly type out this disclaimer...
All that aside, I personally think THE BEST soil aeration amendment is a product called "PermaTill" - I LOVE THIS STUFF. It is basically indestructible, porous, proper particulate size, does not affect pH and has a very high CEC. It CAN BE used as a 1:1 replacement of perlite, and in most cases I find it takes a bit less as it doesn't break up / crush over time...
(this is not a purchase link but a product information link): http://www.permatill.com/home-garden-products.php?cat=8
I'll never buy a bag of perlite again...pay money for 1/3 a bag of dust....no sir...
dank.Frank