I have a 5 ft 100 gallon tank with a 75 gallon sump. I have 2 return pumps. 1 is a dc tunze 1073.050 which is rated for a max of 700 gph. With the pump running on the 12 volt group 31 agm battery, i would estimate it might be pumping about 100 gph. It should do this for several days during emergency power outages. Considering that is far less than my normal return flow, do you think that low of flow will keep the system from crashing? I could add a small tunze 12v powerhead but it will reduce my run time.