Can you explain this sprinkler you are talking about? I had the septic tank cleaned and inspected when I bought the place. I don't know anything about a sprinkler. The pool house has a kitchen and bathroom and it is 8 or 10 feet below the septic tank. I was told there is a "sump pump" to move sewage and grey water to the septic tank.
Who do I call? A plumber? A septic tank installer? When I moved in, the owner gave me the card of a "husband for hire." I hope I still have his card somewhere! I can whelp puppies and foal mares. Just not handy with the hardware stuff!
What are you doing by the cabana????? You are suppose to be resting, not fretting!
If you had an aerobic system (I do have one) you would have at least 3 poles with sprinklers on top of them in your yard. Once every day these sprinklers will spray. Is there a phone number anywhere on or around the 'red light' for you to call. Is there a switch that you can hit to reset? I can't believe your septic tank is full if you had it cleaned out 18 months ago. Has your family been using the pool lately? Maybe something got clogged up in there.
My DH is out at the moment, or I would have him help.

Lisa
