I recently moved into a house with a pool, and I've had a problem with finding debris on the surface of the water. Mostly tiny bits of grass and dirt and winged ants. We don't have ants in our yard, and the pieces of grass are smaller than what you'd get out of a lawn mower. The debris, however, lingers at the end of the pool with the overflow drain and never goes away. The other end is clean, and the filtration system is in good shape. The cartridges are brand new, cleaned, and everything runs properly.
So. I promise this is relevant. The lot next door to ours is vacant, and there are several ant colonies in it. It's owned by Harris county flood control so there used to be a house there - probably torn down after TS Allison and bought through this program: http://www.fema.gov/application-development-process/hazard-mitigation-assistance-property-acquisition-buyouts. (Yes, we're in a flood plane. Yes we're insured. Yes, we knew it before getting the house) Anyway, the pool's overflow pipe goes out towards that property, and on the other side of our fence I noticed a patch of dead grass that has been growing since we started treating the pool for the summer.
My theory is this: When the house was torn down and the lot was cleared out, I think our drainage pipe got cut by sloppy demo contractors, and it’s now feeding into the dirt instead of the sewer (I assume that's how they work). The pipe is probably no longer on a downward slope since one end isn't attached to anything so its angle is subject to whatever ground subsidence occurs, and whenever water goes into the pipe, we get a nice backwash of whatever is in the ground next door - presumably ants, dirt, and grass. And whenever the water from the pool makes its way into the ground over there, the chemicals are leaching into the soil and killing the grass.
I'm testing this theory with a small piece of window screen placed behind the plastic grate of the overflow drain. My thinking is if it gets clogged up with junk from behind and the pool stays clean, it means the pipe is going out into the ground and isn't connected to the sewer like it should be. And yes, I'll be keeping an eye on it. I don't consider the screen a permanent solution.
So... What does the message board community think I should do at this point?