Yeah, I tried the Liquimate brand and had disappointing results with it (I'm being nice here).

But there have been people who've had GREAT results with low-rate peristaltic pumps (used for chemicals, medicines and blood) on timers. You have to hunt up peristaltic pumps on Google or eBay, figure how much bleach you want to pump in, and how many times a day.

I think with some effective planning you can get a pretty good system going for a few hundred bucks.