Pool is clear but keep getting dark spots on liner

jaspers95

Active member
Aug 1, 2019
43
Long Island, NY
After opening my pool I got the chlorine ph and alkalinity good. The pool is clear and the filter is running with good pressure. I keep seeing dark clumps building up on bottom of liner. I’ve tried brushing it which loosens it and shocking the pool but these still come back. Is this just algae and how to recommend getting rid of it?
 

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To kill this stuff, and follow the SLAM process, you need a good test kit. Link-->Test Kits Compared


Proof...Link-->How Clear is TFP Clear?
 
Regular old algae. They are different, but only at the end. Trust me, that is regular stuff. Do they poof when you brush?
 
Algae.

Add 3ppm of liquid chlorine a day until your kit arrives. Nothing else.

Post results when you get and and then we SLAM!
 

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It would be about 1 gal of 10% liquid chlorine. That would roughly get you to 8 or 9 ppm.

Test strips are notoriously untrustworthy, so this would be a reasonable amount to get by with until your good test kit arrives. Although your strip can't be trusted, the CYA might be pretty low, so you may be burning up a fair amount of Cl in the sun. So 3/4 to 1 gal a day for now. Once you get more accurate numbers, we can worry about other things. That amount of Cl will at least hold it at bay, and may begin to make progress until you can start doing the whole SLAM testing and dosing regimen.
 
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The dosage is to add the additional 3 ppm PoolStored suggested, so keep running the SWCG. Once you get your test kit, and can start the real SLAM process, others can advise on the SWCG question. As you get to the end of the SLAM, part of the verification that you are done is to do a test to see if you are losing any Cl overnight. That would be skewed if the SWCG was running.
 
Great job on the test kit!!!

You are probably in bed. Start int the morning...all good! If you are up, SLAM away!!!

Round up your CYA results. Your CYA for SLAM purposes is 50. SLAM FC target of 20 FC.
 
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Began the slam process. Last night I got my FC up to 21. brushed the pool turned the swcg off and left pump on

This morning just measured again: FC still 21 and CC is 0.

Pool is mostly clear except a couple of spots in deep end where wall meets floor.

Also when I brush over the “clear” areas there is a slight “poof” ( took pic with brush but hard to tell) Is this still algae? Should I continue the slam?

You
 

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Began the slam process. Last night I got my FC up to 21. brushed the pool turned the swcg off and left pump on

This morning just measured again: FC still 21 and CC is 0.

Pool is mostly clear except a couple of spots in deep end where wall meets floor.

Also when I brush over the “clear” areas there is a slight “poof” ( took pic with brush but hard to tell) Is this still algae? Should I continue the slam?

You
Before you brushed did this material look like gray dust? If so it’s likely dead algae which means you haven’t met all 3 criteria of the SLAM process. Continue SLAM until:
  • CC is 0.5 or lower
  • AND your overnight chlorine loss test shows 1.0 ppm of loss or less
  • AND pool water is crystal clear with no visible sign of algae (dead or alive) on floor and walls
 
Also when I brush over the “clear” areas there is a slight “poof” ( took pic with brush but hard to tell) Is this still algae? Should I continue the slam?
Dead algae. Follow @Lake Placid advice...continue SLAM until Stoooopid clear.

So let's address why you got algae, so you can avoid in the future. When you are done with SLAM, manage your FC so that when you test it always in range...never let it get below range and you won't have algae again. Follow this link-->FC/CYA Levels

You Got This Good Luck Today GIF by MOODMAN
 

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