Any ideas what this is? Black silt like substance

[ccfc1986]

I noticed that after vacuuming (4/5 hours) after I get this black stuff at the bottom of the pool. If I brush it it dissipates instantly. The walls feel clean and I have a nautilus cc that cleans the walls. My levels can be found with this link from today's most recent set of tests.

Could this just be black soot or pollen or something? Could it be algae? I lost .5 FC overnight (and that is with me testing after sunlight). I think my chlorine lose is minimal over the evening hours so I'm thinking it's not that's however, it just looks horrible. I removed the cover today... Maybe the buildup was from the cover and a good vacuum will make it all go away?

 

[mknauss]

Try using the robot and see if it clears up. I cannot seem to get the picture to open to make it bigger. If the material 'poofs' away when you disturb it, that is typically dead algae.

 

[ccfc1986]

I'll run the robot tomorrow for 2 cycles and see how it looks after. I'll try uploading another image oft it returns after vacuuming. Was too large this time and I took a screenshot to get it smaller. Sorry!

 

[ccfc1986]

Uploaded a new pic for reference. Not sure it helps all that much

If this is dead algae - i guess that's better than alive algae... should i be concerned?

Off to go setup the robot to get busy! Will post an after picture for reference in 3/4 hours.

 

[mknauss]

If this is dead algae - i guess that's better than alive algae... should i be concerned?

If the material is recurring each day, then yes, you most likely will need to follow the SLAM Process

 

[ccfc1986]

OK. I will keep tabs on it over the next few days after each clean I (or better said, the robot) performs of the pool (although i will take extra care to brush everything really good just in case) - and how long it takes to get like the above picture again. If it happens for a day or two in a row - I will follow the SLAM process. Time to go re-read that just in case. Thanks!

I currently do pass the SLAM criteria even with what is going on...

• CC is 0.5 or lower;
• You pass an Overnight Chlorine Loss Test
  This test is intended to determine if your pool has a contaminant such as algae that is consuming chlorine. The test is performed by testing FC in the evening after sunset and again in the morning before sunrise. The readings will be the same if there is nothing in your water consuming chlorine.
  Synonyms: CLT (ie overnight FC loss test shows a loss of 1.0 ppm or less);
• And the water is clear.

Would the SLAM be required even if the above is the case? Sorry for all the questions - just would assume instead of the above criteria - my criteria would be the lack of the black / powdery substance would mean my slam is over? Is that accurate?

 

[ccfc1986]

After 2 hours of the robot doing his thing (does not have the fine filter basket installed, that will be here Friday), thin/small deposits of the black stuff came back and settle to the floor. I assume it's only a matter of time till more does. So next step I think is let it settle... Then grab the manual vacuum and see if I can get more of it manually and force it through the filter?

I added some additional 10% bleach to get to the high end of my FC zone (8) just in case I need / want to move to the SLAM based on the recommendation above.

Per the previous post, I pass the criteria for the 3 tests for a slam already. Will the slam clean up dead algae by itself? Is that why I would still go through that process? Thanks again. Much appreciate all the feedback and assistance!

 

[mknauss]

, I pass the criteria for the 3 tests for a slam already.

If you have recurring debris that 'poofs' away when disturbed, you do not have clear water.

If it recurs after vacuuming/cleaning, it has to be coming from somewhere.

 

[ccfc1986]

Ah, got you. Makes sense. Didn't think of it that way. I think of clear water as "I can see the bottom, it's not green, and if I was thirsty I would consider drinking it". Obviously that last part isn't true, but your description make sense entirely.

Should I just start my SLAM now?

The pH might be a little higher than we may like to start a slam (7.4/7.5). At least according to the YouTube videos ... Further down it says between 7.2 and 7.5 is acceptable. Should I reduce it to 7.2? I have MA on hand.

I'll go start brushing all the surfaces regardless. Probably not a bad thing to do anyways. Thanks again!