Help in identifying fine powder like substance

[estak]

Hello fellow pool owners!

Most of you are probably in the northern hemisphere and enjoying some nice and warm weather. It's a bit colder here in Sydney, but based on the mild winter we're having, I have a feeling we're going to have a hot summer!

Anyway, my question relates to some fine dust like particles that always settle at the bottom of our swimming pool. The only way I can seem to get rid of it is to vacuum to waste, but it just comes back in a week or two.

I'm wondering whether anybody else might have had similar problems and what they did to get rid of it. I don't think it's algae. We have large native trees surrounding the pool, so it might be something coming off the trees perhaps?

Anyway, interested in your opinions.

 

[Texas Splash]

Hello! To help us ensure it's not algae, can you share a full set of water test results? What type of trees do you have nearby? Have you tried putting a sock or fine mesh over a return jet to see if you can capture any of that stuff? How old is your filter and have you ever performed a deep cleaning of the sand?

@AUSpool might have additional questions for you based on local conditions.

 

[duraleigh]

I think it might be plain ole' algae.

I would agree with Texas to perform an OCLT and post up a current set of test results

 

[mgtfp]

What do you mean with "colder" in Sydney? Been there two weeks ago. Tropical compared to Melbourne.

Apart from complaining about Melbourne weather, I can't add much to what has already been suggested. Step 1 is gathering data.

 

[AUSpool]

First up would be an OCLT and a set of current test results. The water would be cold right now so everything is a bit slow. Are your pumps set to low speed through winter? Does this happen seasonally? I know its winter but are there any trees that are blooming or blooming early? Are you coastal? Is there any major construction involving ground works nearby? Are you using any anti phosphate products on maintenance doses? There are a few possible culprits, algae being the first and it does look like that. I’ve had similar but what I had may not be what you have.

@needsajet is a bit closer and my know something more specific then me.

 

[estak]

Wow, thanks for the suggestions. Lots there for me to pick through.

To answer some of the questions:
* Types of trees - very large ones! more specifically, turpentine and blackbutt
* Used a sock - I have used a sock in the skimmer basked previously. I think I have a couple left over so might try again.
* Age of filter - I'm guessing the filter is pretty old as it came with the house 7y ago, but the media is about 4-years old.
* Deep cleaning sand - good suggestion, I'll be sure to do this soon.
* Pump set to low speed through winter - we don't have a variable speed pump (yet), but I reduce the chlorination run time throughout winter. However the substance is there all the time and not just winter.
* Blooming trees - no blooming trees yet. I have a wave of seeds, pods and shedding bark coming soon, but it hasn't quite started yet.
* Am I coastal - no. About 15-20km from the closest beach.
* construction nearby - no major construction nearby
* phosphates - I'm not using any additional products in the pool at the moment.

Looking at all of the questions and answers, it's pointing towards algae. I'll conduct OCLT as suggested, add the sock and check chemical levels.

Thanks for the assistance and I'll update the post again when I have done some of the things suggested.

@mgtfp I'll try and send some rays your way on Saturday (Forecast for 23degrees)

 

[needsajet]

Actually the air has been beautifully clear here in Sydney for the last few weeks , a bit windy though which increases construction and diesel particulate in the air. The wind also puts more leaves in the pool which contribute to algae risk.

Very likely nascent algae. Algae doesn't become visible until it's already really bad and forming colonies which are visible as green and brown patches.

Overnight Chlorine Loss Test may or may not show up the problem while the water is so cold but should be zero overnight chlorine loss at this time of year.

If it were mine, I'd go ahead and SLAM Process for a couple of reasons. It will eliminate algae from the equation. There's no downside except for a couple potential problems caused by high pH (metal staining and calcium scaling). Provided you observe the rule to reduce pH before SLAMing, those risks are pretty much eliminated. The stipulated pre-SLAM range is 7.2 to 7.5 and I personally prefer 7.2.