Hi new to the forum and fairly new to pond keeping I have just built a new pond 5m x 2m 1m deep from railway sleepers I installed 1 bottom drain in the middle and have made DIY filtration system 1 vortex 1 static media and 1 moving bed media it has been running about 4 weeks and was running really well but the other day the water stopped running back into the pond and no matter how I reposition the filters it runs for a little bit and stops again the water level in the vortex seems to settle just under the outlet and only just trickles into the next barrel help please