Pool dirty only when pump running

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Relium

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Jun 30, 2015
7
WINNIPEG
I've got a swg pool that is constantly dirty. Vacuum pool and 6 hours later pool is dirty again. Pool has been doing this for over a year. It is clear and has been since the initial algae after opening. Levels have been testing good, I keep FC on the high side of the range, around 6 for a CYA of 60... I have swg remember. Tests are done with Taylor FAS-DPD kit.

I know it's not airborne debris blowing in pool as when I tested with pump off for a day, the pool stayed clean, except for a little debris that may have blown in but nothing like when pump is running.

We thought filter was the issue so it was replaced. Brand new sand filter doing the same thing as old.

We thought algae, so we brought chlorine levels to SLAM levels for a week (30+ppm FC with CYA of 60). Did not solve issue.

Sock over return for a day captured very little debris (a few particles of dirt, nothing like what is on bottom).

I've read other posts on the forums with people having this issue however no one has been able to give a clear conclusion to a fix.

My only theory is that main drain is drawing in soil through a crack while pump is running and particles are too small for sand filter to catch? However, pool has been vacuumed on waste as well with no difference in debris. As well, no water loss with pump off (at least nothing significant to measure).

Other details about the pool: it is located in Winnipeg MB, there are trees nearby but nothing in the immediate vicinity, house is located river side and there is a park across the street with play sand. While this may sound like a disaster for pool debris, again with pump off, pool stays clean.

Anyone know what is going on? Is my theory about main drain possibly correct? Should we plug this drain and see if it helps?

Thanks in advance for the help.
 
Relium,

Weird. If pump on is the only time you have this I'd say you're getting the dust from the filter. Try back-washing longer. What does the "dirt" look like?

Even though this is a very weird problem the drain leaking in soil seems pretty unlikely.

Chris
 
We've tried backwashing for longer than necessary (around 5 minutes). Normally we backwash until water runs clear and then rinse for about 45 seconds. Nothing visibly returning to pool when we turn pump back on after backwashing. Only notice sediment at bottom of pool after a few hours.

The sediment is mostly deposited in the deep end but there is some dispersed everywhere. It looks black, very fine and clouds up when brushed. No green or yellow color to it when brushed up (again, pool was SLAM'd for a week).

The reason I theorize it may have to do with main drain is that there is some air bubbles that run through pump constantly. Plumbing is old and when pump is turned off, you can hear some air bleeding from system near a valve or possibly pump lid. My assumption is the air bubbles are coming a weakened connection near the 3 way Jandy valve (that's where it sounds like it's coming from).

I can replace this plumbing to hopefully remove air, but is this really what would be causing the dirty pool? My assumption is no but I guess it can't hurt to try.

Plans are to renovate pool hopefully next year (new liner and decking at the very least). We would just like to get to the bottom of this dirt issue prior to that if possible. If I have to replumb before the renovations, then I will.

If anyone has any other ideas, I'm all ears.
 
Have you been able to collect any of this material in socks, etc. on the returns?

The only thing I can think of that might be black is a degrading seal in the pump, multiport valve, or something similar. But that would be somewhat "greasy" and probably smear when brushed.

Pics may be helpful here.
 
Relium said:
I've got a swg pool that is constantly dirty. Vacuum pool and 6 hours later pool is dirty again. Pool has been doing this for over a year. It is clear and has been since the initial algae after opening. Levels have been testing good, I keep FC on the high side of the range, around 6 for a CYA of 60... I have swg remember. Tests are done with Taylor FAS-DPD kit.

I know it's not airborne debris blowing in pool as when I tested with pump off for a day, the pool stayed clean, except for a little debris that may have blown in but nothing like when pump is running.

We thought filter was the issue so it was replaced. Brand new sand filter doing the same thing as old.

We thought algae, so we brought chlorine levels to SLAM levels for a week (30+ppm FC with CYA of 60). Did not solve issue.

Sock over return for a day captured very little debris (a few particles of dirt, nothing like what is on bottom).

I've read other posts on the forums with people having this issue however no one has been able to give a clear conclusion to a fix.

My only theory is that main drain is drawing in soil through a crack while pump is running and particles are too small for sand filter to catch? However, pool has been vacuumed on waste as well with no difference in debris. As well, no water loss with pump off (at least nothing significant to measure).

Other details about the pool: it is located in Winnipeg MB, there are trees nearby but nothing in the immediate vicinity, house is located river side and there is a park across the street with play sand. While this may sound like a disaster for pool debris, again with pump off, pool stays clean.

Anyone know what is going on? Is my theory about main drain possibly correct? Should we plug this drain and see if it helps?

Thanks in advance for the help.
Click to expand...
Welcome to the forum!

Did you pass all three criteria to end your SLAM?

It may be a good idea to do an OCLT to rule out organics, as your description sounds a lot like dead algae.

If there is a chance of soil being drawn into the main drain plumbing, the contaminants should be drawn into the filter, not the pool.
 
No, I haven't been able to collect much in the socks. As I said, very little debris was caught in sock and nothing like what is on bottom of pool.

dbtgallery.php


That is what it looked like after having pump off for about 12 hours. Sorry I do not currently have a photo with it when pump has been running but it looks like that, but tenfold the amount. I can try getting a better picture tonight.

I feel like with the amount of sediment at bottom of pool, a degrading seal would be fully degraded by now after almost two years of this (we have vacuumed on waste on multiple occasions so it isn't simply the same debris returning to pool)

We passed the OCLT every night of SLAM'ing. Again, chlorine levels were kept around 30ppm for a week (CYA was 60 or around there, the Taylor test kit was used).

I should mention that I also removed our deep end ladder and inspected for algae, seemed like there was none on or inside (behind plugs).
 
Quite the odd occurrence ---

There have been threads in the past were a sand filter, filled with certain sand or the fake stuff, has caused this. Primarily due to low quality sand, too fine, etc.

Not sure if that would apply. You might try searching the forum for any threads on unable to filter pool clean with sand filter.

Take care. Good luck.
 
That is that right size sand.

Odd -- can you shut off the suction from the main drain? I agree with Dom that it should be filtered out but might be too fine?

A mystery ------------
 
Yes, I'm going to try shutting off the main drain with the jandy valve and seeing if it makes a difference. As I said, the plumbing is old so not sure if jandy valve will even be sealed tight. Will update later tonight or tomorrow if the main drain being off makes a difference.

Btw I should mention we have a hayward 1hp pump and hayward 27in sand filter so pump shouldn't be oversized I don't think?
 

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If closing the main drain didn't change anything we can eliminate that as the source.

If using a sock on the returns does not trap anything we can also rule out the return water as a source (unless you used a sock with holes in it LOL).

The only thing left is some kind of outside contamination, and the theory of this only happening when the pump is running could be coincidental.

I would try another OCLT just to be safe that this is not algae, an ounce of prevention is worth a pound of cure......
 
Was your pool replastered or is it a new pool? If it was replastered, did they sandblast the pool? I just had my pool replastered and they used a very fine black sand that is very heavy. They didn't block my returns or skimmers, so the black sand got all inside my plumbing and is still making its way out into the pool. Thankfully the rate of new black sand is decreasing. I even get some of this sand blowing in from my yard. I may end up shop vacing the perimeter area to end this!

Of course, you should still do the OCLT as mentioned above to rule out organics.
 
Relium said:
We've tried backwashing for longer than necessary (around 5 minutes). Normally we backwash until water runs clear and then rinse for about 45 seconds. Nothing visibly returning to pool when we turn pump back on after backwashing. Only notice sediment at bottom of pool after a few hours.

The sediment is mostly deposited in the deep end but there is some dispersed everywhere. It looks black, very fine and clouds up when brushed. No green or yellow color to it when brushed up (again, pool was SLAM'd for a week).

The reason I theorize it may have to do with main drain is that there is some air bubbles that run through pump constantly. Plumbing is old and when pump is turned off, you can hear some air bleeding from system near a valve or possibly pump lid. My assumption is the air bubbles are coming a weakened connection near the 3 way Jandy valve (that's where it sounds like it's coming from).

I can replace this plumbing to hopefully remove air, but is this really what would be causing the dirty pool? My assumption is no but I guess it can't hurt to try.

Plans are to renovate pool hopefully next year (new liner and decking at the very least). We would just like to get to the bottom of this dirt issue prior to that if possible. If I have to replumb before the renovations, then I will.

If anyone has any other ideas, I'm all ears.
Click to expand...

Sorry for the long delay... went sailing. You seem to be resistant to confirm you actually completed all of the criteria for the OCLT test and you actually did everything required including the scrubbing and never letting the FC drop below the SLAM level. The reason a lot of people on here keep asking this is that many of us have had the same issue and it turned out to be algae (including myself) that looked like a brown powder. I suspect it was dying or dead algae that had not yet been completely oxidized by the chlorine reactions but I can't confirm this. A meticulously complete SLAM could help a lot to narrow down the source. So here are a couple of other ways to confirm if it's dirt or algae. First, you can carefully remove some with a syringe and make a slide to view under a microscope. Any low power scope will work, you might get help from your local school science department or Google how to do this. It's very simple to do and extremely easy to differentiate dirt from algae but you need a microscope and to be able to prepare a simple slide. Another way to do this is to put a sample as concentrated as you can get in a small glass container then boil off the liquid slowly until it's dry. Dirt will not change much in appearance as you dry it. Algae will almost disappear since it's 98% water.

If you find this is actually dirt and given all the things you've checked I'd bypass your filter and run the pump. If you eliminate the problem this way then you confirm it's the filter. If not, I'm stumped

The reason I don't think it's your drain is that the pressure outside of your drain fitting would be less than the pressure inside from the water column in your pool when the pump is off (and even when it's on in many cases). This would mean water would be leaking out and you've not mentioned anything about water loss.

I hope this is helpful.

Chris
 
The "dirt" could be dead algae which can pass through a sand filter. Either vacuum to waste or try a little DE in the filter.
 
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