New Liner Replacement and Mustard Algae Prevention Prior to the Installation?

[Hoster]

Background:
1. inherited the pool from previous owner(s) with the liner of 10+ years
2. started leaking and decided to replace the liner
3. with the old liner, I have been experiencing mustard algae (I think - almost impossible to get rid of) in specific areas of the pool
4. the old liner is removed and I now see the exact spots underneath the old liner (see pic) where mustard algae developed

Advice needed/ questions:
1. the shape of mustard algae was exactly the same as the dark green spots (4 or so of them) you see on the picture
2. those spots appeared only when the Chlorine level was low

Is this something I can / should "remove" before installing the new liner or not worry at all with the new liner? If so, what is the best way?
I did brush for a min with some bleach but did not try to completely remove the spots.

Thanks in advance for your insight!

 

[frustratedpoolmom]

That's not mustard algae. It MIGHT be black algae. If the spots were affected by bleach, then by all means, hit it.

If spots showed up when chlorine level was low, then the chlorine level was too low. I had a similar situation in my above ground pool, and that's what led me to TFP.

 

[Hoster]

thanks!!