Persistent Algae in Pool

[Green_Algae]

This is my first year using a TF-Pro test kit. I've been struggling with reading the PH and CYA levels and wonder if that is my problem.

These pictures are from today and here are my test results for today:
PH = ? 8 maybe? Probably too high
Free Chlorine = Visually looks like it's between 2 and 3 so... 2.5?
Free Chlorine Drop Test = 3.5
Combined Chloramines = 0
Alkalinity = 110
CYA = Less than 30?

This is a chlorine pool and I use liquid chlorine. I know it goes against the wisdom of this forum but I also use a small amount of chlorine pucks. In past years I would have the puck sit in the skimmer basket and replace it when it was gone. This year I had a pool company come out and add a Hayward in-line chlorinator. They also changed the sand and fixed my sand filter. I run the pump on a timer from 9:30am to 8:30pm.

I regret getting the chlorinator. I am concerned about adding too much CYA to the pool and have kept it on a lower setting. Since this Algae won't go away I have held off increasing how much CYA is released by the chlorinator as I am concerned that I could be totally wrong and perhaps I have too much CYA in the pool.

For the past few weeks I have been stirring up the pool with a robot vacuum and keeping the chlorine level high but this stuff just won't go away.

Any advice would be much appreciated.

 

[PoolStored]

Welcome to TFP!!!

pH looks to be between 7.8 and 8.0.
Ignore the block test for FC, just use the powder reagent test. Your FC is 3.5

Try this with your CYA test. Stand outdoors, with your back to the sun. Fill to the first line. Hold and your waist in front of you in the shadow of your body. Glance. If the dot is visible, fill to the next line. Repeat until the dot is obscured. Take the number on that line and add 10. That is your CYA. The outdoor light is important.

Follow the SLAM process to clear the pool. Link-->SLAM Process

 

[JJ_Tex]

For the past few weeks I have been stirring up the pool with a robot vacuum and keeping the chlorine level high but this stuff just won't go away.

Any advice would be much appreciated.

"high" is a generic term. What have you been keeping your chlorine at that you are calling high? 3.5?

I'm not trying to nitpick, but algae is a product of low chlorine and lots of people have skewed perceptions of "high" levels of chlorine. Here we go by the FC/CYA ratio which you can find the link in Pool School or my signature.

 

[TinFoilHat]

You also have to brush and scrub the algae to take the surface skin off of the cells so the chlorine can kill it. The robot won't do that.

 

[Newdude]

Have you done an Overnight Chlorine Loss Test ?

My stairs amd pool often look exactly like yours and in my case, its runoff from the patio.

 

[Green_Algae]

"high" is a generic term. What have you been keeping your chlorine at that you are calling high? 3.5?

I'm not trying to nitpick, but algae is a product of low chlorine and lots of people have skewed perceptions of "high" levels of chlorine. Here we go by the FC/CYA ratio which you can find the link in Pool School or my signature.

I haven't been aiming for a certain number. The block test for Free Chlorine always has yellow in it. Often it is dark yellow and I'll do a drop test and get a number like 7 or 11. I'll scrub the pool today and keep adding chlorine to keep it at 12 to try and clear this. Thank you.

 

[Green_Algae]

You also have to brush and scrub the algae to take the surface skin off of the cells so the chlorine can kill it. The robot won't do that.

Interesting, I will do this.

 

[Green_Algae]

Welcome to TFP!!!

pH looks to be between 7.8 and 8.0.
Ignore the block test for FC, just use the powder reagent test. Your FC is 3.5

Try this with your CYA test. Stand outdoors, with your back to the sun. Fill to the first line. Hold and your waist in front of you in the shadow of your body. Glance. If the dot is visible, fill to the next line. Repeat until the dot is obscured. Take the number on that line and add 10. That is your CYA. The outdoor light is important.

Follow the SLAM process to clear the pool. Link-->SLAM Process

I will try the CYA test in a different setting, thank you.