I have a SunSun 304B. The way they construct the intake tube in sections, starting near the water line, allows for air to enter the system if the water level is below the first connection. I prefer the way the Pingkay filter intakes are made with a long initial tube with extensions placed at the bottom of the tube. I suspect the filter ran low on water while the UV was on and the high temp of the bulb cracked the casing. I guess you could silicone the intake tube pieces together to stop the air leak.