I found IA to be dirty and a water quality problem. However, if you need a lot of phyto it can save you a LOT of culturing room and effort. Many breeders use it very successfully. Given the alternative, I use IA, too, but I am growing a little live phyto now to use in larval tanks to tint the water green so I avoid some water quality issues.
To slow down rotifer production, lower the temp to slow metabolism and reduce feeding to keep the population down.
When I have babies to feed, I feed the rotifers a combination of instant algae and a yeast-based food. I harvest half every 24-36 hours and enrich them for 12 hours in an enrichment media, then feed the larvae the enriched rotifers. I replace the 50% water I took out with new salt mix. I harvest every 12 hours, but rotate cultures so I can feed every 12 hours. For L-strain rotifers, keep the temp nice and warm around 82F. (I don't heat mine; I don't need many rotifers and I get more than I can use at 70-72F room temp and my cultures are more stable at a lower temp. I seem to be in the minority on that.)
On "simmer," I only feed a little bit of yeast each day and harvest half from each culture every 2 days, replacing the water with new salt mix. This keeps the density relatively low but healthy, and I can ramp up to "production" levels within a couple of days. Turn off the heaters or turn them down to 70F-ish.
Yes, harvesting a healthy culture more often makes you get MORE rotifers. It's wierd but true. I use Clor-Am-X in the cultures to reduce crashing from ammonia; rotifers are dirty critters.
If there's one thing I learned, you MUST keep to your maintenance schedule. Slacking off can get you a bucket full of dead smelly sludge very quickly. And I mean SMELLY! You can get the smelly sludge even if you are careful, so keep more than one culture going at all times and rotate maintence among the cultures.