Another Piping Design Question


Well-known member
Jun 29, 2017
Augusta Township, Michigan
Hello all,

A few weeks ago, I posted on here and got some great advice regarding the current design of my above-ground pool filtering system. The original post is here:

Why is my filtering system built like this?

I went to take a look the system today to start making a material list, and I forgot about the "third pipe" he installed. I'm not 100% certain what it's for or if it's needed.

I posted some actual pictures of it this time, instead of a sketch. Both pictures are basically the same, just slightly different angles. Please look at the first picture, Piping1.

The pipe all the way to the right comes from the skimmer to the filter. The pipe in the middle is the return line from the filter back to the pool. Great. But notice that the feed line has a bypass pipe, and I have no idea what it's for. If you close the valve all the way to the right and open the one all the way to the left, you can get water to come out of the bottom of the pipe that is in the background, under the deck near the pool. I guess it would sort of make sense if it was in the return line, a way to drain the pool or something. I assume I can redesign the new piping system without this bypass?


Divin Dave

TFP Expert
LifeTime Supporter
Oct 2, 2013
Longview, Texas
So that pipe all the way on the left. It is Teed off the Suction Pipe from the skimmer, It goes under the deck and then makes a 90 deg turn down. Is that right?

If so, then that can only be a way to lower the water level in the pool. Or like others said, someone was trying to be tricky with it which makes no sense either. Thats my take on it.

EDIT. On second look at the pic. It doesnt make sense that it would be put there as a drain of some sort. The downturned pipe has a valve and a coupling on it. I understand the valve if someone was trying to be tricky, but not the coupling. So, something at some point in time must have been connected to it via that coupling.... ? but what?

I dont know man, Its certainly wierd.

So, my opinion you dont actually need that if you're going to re-pipe the plumbing.
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