That's right, you can't control the 6025 or 6045 only the 6055 can be pulsed and is a DC model. The 25&45 models are 100% AC and can start backward so it's not a good idea to run them on a switching controller. However if you have 2 of them you shouldn't need to worry about that, point them at 45 degree angles toward the front tank and they should create crazy chaotic water patterns.