dirty lines

[docsPool]

15 year old 50’ x 25’ in ground pool w/vinyl liner, Sta-Rite System 3 S7M120 filter.

For first time since installing pool, dirty lines are forming between the seems of vinyl along bottom of pool on a daily basis. Chemistry is always balanced and water is crystal clear. I am cleaning out filter housing and cartridges often, but the next day I have dirty lines and have to vacuum again.

Can someone please tell me what I am doing wrong?

 

[mknauss]

Welcome to the forum!
Can you post a full set of test results from your own test kit?
What you describe is typically dead algae. Does it 'poof' away when you brush or get a vacuum near it?
I suggest you read ABC's of Pool Water Chemistry.

 

[Newdude]

Whats up Doc ?? Welcome !! It sounds like you are on the verge of an algae explosion. If the situation is right it can stay on the fence for an extended period of time and not appear to be a problem. Your sanitizing is working, but only enough to keep it from getting worse. The root of the problem is still there as evident by the dead algae. It typically collects anywhere there is a transition like seams and corners, and sometimes in front of returns.

 

[docsPool]

Thanks for replies.
I keep the Cl at 5 and the pH at 8.2
"Does it 'poof' away when you brush or get a vacuum near it?"
Yes
I just vacuumed and cleaned out cartridges and filter housing yesterday, and there are dark lines already!
Do ya think I should give it a shot of algaecide?

 

[Wobblerlorri]

Instead of algaecide try the SLAM Process. It will really clean your pool and without adding magical mystery potions.

 

[Newdude]

Algaecide only works as a deterrent before the fact. It does nothing afterwards. And you have to be careful when selecting which Algaecide because most have copper in them which opens up new problems.

 

[mknauss]

"Does it 'poof' away when you brush or get a vacuum near it?"
Yes

You need to follow the SLAM Process. To do that, you need a proper test kit. I suggest the TF100. A proper test kit is needed to get the accurate water chemistry results needed to follow the TFP protocols.

While you are waiting on your test kit, add 5 ppm FC worth of liquid chlorine / plain bleach to your pool each evening with the pump running. This will replenish the FC lost each day to the sun and also inhibit any algae in the water from growing further.