Mystery of Sediment Upon Opening

[poolboy234]

Hi all,

I have an in-ground, chlorinated pool with a newer cartridge filter (cleaned every winter) and heater. For each of the two past seasons, my pool is crystal clear all winter with the lines plugged and everything dormant. But immediately upon opening the pool and turning on the pump/opening the return jets, sediment begins to come through the jets and lies at the bottom of my pool. With regular vacuuming for the first couple of weeks of the season, the issue stops.

My pool company is stumped by this. Given the filter is cleaned and stored over the winter, it seems the issue must be in my pipes? But I have zero water loss and so I can't imagine dirt is getting through a crack. I don't know what to do and no one locally seems to be able to figure it out. The lines are blown out before closing, but could residual moisture in the pipes create algae and I'm seeing dead algae that accumulated in the pipes over winter kick back in at opening? I don't have any other ideas.

Thank you so much!

 

[Newdude]

Did you Overnight Chlorine Loss Test ? Its most likely growing algae that you're killing to find it dead on the floor. (Yes, even with clear water).

 

[poolboy234]

Did you Overnight Chlorine Loss Test ? Its most likely growing algae that you're killing to find it dead on the floor. (Yes, even with clear water).

It's nonexistent though until the pool is opened and the pump is running for ~5-6 hours. Would this mean the algae is in the dormant pipes all winter and that's why it's suddenly an issue when I open the pool?

 

[Newdude]

No you started adding chlorine which is now killing the previously mostly dormant algae in cold water.

Pass an OCLT and rule out the most common occurance first.

 

[poolboy234]

(edited and will do the OCLT )

 

[poolboy234]

Although I'll add: a couple of weeks ago before I opened the pool, I added chlorine (I have an auto-cover and so I opened it), but still no sediment until the pool was opened this week and the pump began running. Question being why if chlorine was killing the algae causing it to settle at the bottom of the pool that this does NOT happen when the pool is not open and the pump isn't running?

 

[Newdude]

I will absolutely run an OCLT, but assuming it isn't that, what would the other possibilities be?

I hesitate to even say it because we have thousands and thousands of pools properly closed each year with zero pipe crud issues. But if your pipes were growing some kind of freakish crud, there is an ahhsome line cleaner that would expel it. Its typically used for baqua dosed pools.

We had someone use it last year with a white water mold problem similar to the baqua users, but it added some time of excessive FC demand while it cleaned the plumbing. Hopefully we get lucky and its just regular old algae.

 

[poolboy234]

Thanks Newdude! Just making sure you saw this followup from me: "Although I'll add: a couple of weeks ago before I opened the pool, I added chlorine (I have an auto-cover and so I opened it), but still no sediment until the pool was opened this week and the pump began running. Question being why if chlorine was killing the algae causing it to settle at the bottom of the pool that this does NOT happen when the pool is not open and the pump isn't running?"

Appreciate you so much!

 

[Newdude]

Question being why if chlorine was killing the algae causing it to settle at the bottom of the pool that this does NOT happen when the pool is not open and the pump isn't running?"

It may not have been mixed well enough or 0 FC rain runoff sat there festering until your next chlorine add / mixing. Im not saying it has to be algae, just that it usually is and the OCLT (which you're doing ) is the first step for all filtering or sediment issues.

It could also be pollen which is now being stirred up when it wasn't, which just so happens to hit about the time you feel you should open. It would also explain why it goes away on its own in a few weeks, with no other effort devoted to it.

If the pipes are expelling organics you will fail the OCLT. (Slam will probably fix it)

If the pool has algae you will fail the OCLT (slam definitely will fix it)

Or its pollen and we wait it out.

 

[poolboy234]

Thank you so much! Appreciate you greatly.