Looks like they finally stopped spawning on the frogspawn it self? With rotifers I keep one bucket in the garage with a heater and a second in the garage without a heater. The one without gets all the way down to 40 degrees some nights and only tops out around 55/60.
The one advantage to that bucket is that it only needs to be fed once a day (sometimes once every two days), doesn't need to be topped off barely at all, and doesn't need very much in terms of water changes.
It definately produces much slower, but at this point I really only need one bucket to supply enough rotifers for my fry tank. In many ways it gives me a solid back up if the main rotifer bucket crashes for some reason.