“Sand” or could this be dead algae?

[LgHorn]

So, I continually get what appears to be fine grains of a sand like substance in certain areas of my pool. It mainly is in corner of my shallow ledge next to top step, along the floor/wall curve in far side of shallow end, and along my bench in deep end beneath my spa (w/spillway). Nothing on vertical surfaces. I can brush or swipe it away, but it will accumulate there again by the next day. When I carefully touch with my finger it feels like fine grains of sand. I have OK flagstone coping, but it’s not disintegrating or eroding and we do not live in a sandy climate / environment so not sure where else it could come from if sand. I do get a lot of yellow/orange pollen in the pool daily from the dozen crepe Myrtle trees the previous home owner planted, but again, this feels gritty and the pollen is usually on the water surface.

My water is crystal clear and I just converted to a SWCG on 7/13 - still trying to get it dialed in to maintain target FC. I’ve managed to maintain the min FC level, but still working on SWCG setting and pump run time to maintain target FC. It’s been extremely sunny and hot here the last couple of weeks. I just got the CYA test tube with the sliding dot yesterday to compare with the standard one combined with the Taylor pH multi vial. Pretty sure my CYA is between 70-80 as that’s the average I get from both tests.

I have had algae blooms in the past and this stuff LOOKS similar to dead algae seen during/after a SLAM and accumulated in generally the same areas, but presume that’s due to circulation. I have not performed an OCLT yet because I have no other reason to suspect algae. My CC has been 0.2-0.4, sometimes 0, for the last 2 weeks.

Pics of what I’m seeing and recent results attached. TIA

 

[mknauss]

Looking at your Poolmath test logs you are running at or below minimum FC each time you tested. That is not good.

Can you capture some of this material (turkey baster?) and put it on a paper towel? If it smears, it is dead algae.

 

[LgHorn]

Looking at your Poolmath test logs you are running at or below minimum FC each time you tested. That is not good.

Can you capture some of this material (turkey baster?) and put it on a paper towel? If it smears, it is dead algae.

Yes, I’ve been at the min, and once up to 5’ish, until last night when my result was 2 and I added half gal of 10%. I’ve been bumping up the SWCG output in 5% increments trying to get it up.

I will try to get a sample of this substance and see how it looks out of the water. Will also do an OCLT just to see if there may be an unseen algae battle going on.

With the TX sun/heat I may just have to crank the SWCG near max but I know I need to confirm if there’s anything else that may be using up chlorine. I have my spillway circuit set to refresh the spa from pool 45 min early every evening and when I tested my spa FC level last night it was near zero. No bueno.

 

[LgHorn]

I siphoned some of the matter from two different spots with a large syringe and emptied into a paper towel. Only one small piece could I smear - it looked like a piece of dirt before smearing. The rest just spread out and once dry (see photo) it appears to be various sized sand and rock. I could move it around and push into a pile on the paper towel. The photo is darker than actual, aside from the smear it has the color of beach sand. I also can run my foot across what’s on the pool floor and am able to feel the grainy texture with my toes.

I might add that I have a lab who swims daily and regularly tracks through the flower beds hauling dirt and whatever else into the pool.

I am going to perform an OCLT tonight and see what it shows. Pool FC was up to 4.8 this evening with 0.2 CC. Spa FC was 4.2.

 

[mknauss]

Looks like dirt.

With a dog bringing in dirt,etc, you want to maintain a higher FC. Target at least 10% of CYA.

 

[LgHorn]

Looks like dirt.

With a dog bringing in dirt,etc, you want to maintain a higher FC. Target at least 10% of CYA.

Thanks Marty.

Guess I’ll be bumping the SWG up to 100% (currently 80%) while we’re having high heat and lots of sun. Running my pump nearly 12 hrs currently, mostly low rpm. I knew the iChlor 30 would likely be a bit undersized, so I plan to run it as needed till it goes kaput and move to an IC-40 or even IC-60 cell.

Will update OCLT results in the AM.

 

[LgHorn]

OCLT just passed - exactly 1.0 FC loss with a couple of light rain showers overnight. CC @ 0.4.

I’m hoping it is just dirt and some sand (from somewhere) and circulation is congregating in these areas. Our friends down the street also have a daily swimming dog and OK flagstone, but no “sand”. Every pool is different so maybe just our yard, dog and materials.

I’ve bumped the SWG up this morning and will target getting my FC to 7+.