Deck fountain PVC pipe green algae

[Goolsbymd]

So we recently purchased this house with a pool and there is a PVC pipe directed straight up uncovered towards the sky. Took a look today and it was filled with standing water and green algae. I took some extra PVC pipe and made an attachment so it wouldn't blow into the pool and with pump running I opened the valve which was isolating it. I blew it out for 10 seconds then shut valve, soaked up some water then poured in a dose of CL. And covered pipe. Should I shock the pool and refill that piping with the new water after shocking or should the CL I added do the trick? It's the longest piping length as its furthest from pump.

[waterbear]

So we recently purchased this house with a pool and there is a PVC pipe directed straight up uncovered towards the sky.

Any idea why? Can you post a pic? Most deck jets are not just plain PVC and are buired in the deck in a box. Sounds like itwas a place where there was some type of water feature that was removed or possibly a hookup for a slide.

[Goolsbymd]

It's for a water feature, it is in a hole with a safety plastic cover over it. However the plastic cover has a hole the exact location where the PVC pipe is lol.