Just ordered a 50lb bag of this stuff
 

Osmocote 19-5-8 Slow Release Fertilizer w/minors. Looks like pretty good stuff, and has calcium and magnesium. My daily fertigation on a number of fairly large containers is a bit labor intensive during the heat of summer, in addition to all the watering by hand. There's a $10 coupon for first time buyers. The bag should last me several years, but I'll probably be tempted to use it on my in-ground plants too, so it'll probably be gone in a year ;)

[url]https://www.amleo.com/osmocote-19-5-8-slow-release-fertilizer/p/1958/[/url]

Amleo frequently has free shipping offers. Well worth joining their mailing list to get them.

The potassium level is quite low for tomatoes.
Should at least be higher than the N level, more ideally close to double the N.

You make a good point about the potassium. Am still using Texas Tomato Food. I also use MG shake and feed for tomatoes, and it also has higher potassium. Will start doing some research for a slow release potassium to add to it.

edit: Come to find out they're out of stock. I'll just stick with my TTF.

Osmocote generally is great, but not cheap, buying a 25kg bag of Yara or Haifa (they have like a zillion formulations) should be a a lot cheaper. That price seems pretty good though compared to here.