I think it is better to remove the last sentence, “Which may cause coagulate of some waste and the oxygen-deficiency fermentation process begins to deficiency the septic process”
Because I don’t think it describe what really happened on the day.
Actually what really happened I think is that I kept on flushing water so it probably caused re-agitation of the sediment inside septic tank. And waste water was pushed off (forced to discharge) while it is supposed to be staying much longer period under normal operation.
The rest part is fine I guess.