I'm trying to determine if I have a mustard algae problem or something else. Last Friday I noticed about a 6-ft long section of brownish/green along the coped (45 degree) surface that meets the deep end of my pool. This side of the pool is mostly in the shade now from trees, etc. It easily brushed away and and I vacuumed to filter and then backwashed. The next day, in the same spot I noticed 1-foot strip the same color residue start to form. Here's a picture:
It's a vinyl liner pool, and you have to really zoom in to see it ... look at the white "grout" lines and notice the discoloration. I looked around the rest of the pool and found a couple other similar areas that had the same discoloration. Here's another pic on the opposite side of the pool:
You can see the discolored on the partial tiles along the seam.
Thinking it could be algae, I started a SLAM on Saturday. My tests (using TF-100 test kit) from Saturday morning were:
FC 5.0
CC 0.0
pH 7.7
TA 90
CYA 40
I added liquid chlorine to raise the FC level to 16 (after reading some more, I realized I should've lowered my pH first). I brushed and vacuumed to filter on Saturday and restested/added chlorine every 1 to 2 hours to keep up FC. I did an OCLT Sat night/Sun morning, but obviously messed up the Sat night test because I had 13.5 Sat night and 15.0 on Sat morning ... I blame drop counting fatigue on the Saturday night test.
On Sunday, I continued to test and keep FC up at 16, and brushed and vacuumed again. Performed the OCLT test, this time testing twice on Sunday night - 16 FC, and twice this morning - 15.5 FC and 0.0 CC. So I think I passed the chlorine loss test.
However, looking at the hot spot in my pool this morning, I can vaguely see the discoloration starting again.
Could this be mustard algae? With the little chlorine loss and no CCs, I'm at a loss. Starting this week, we've started to have a lot of leaves fall in the pool, so I'm constantly emptying skimmer baskets and skimming the pool. But if from the leaves, I wouldn't expect the discoloration to keep forming in the exact same spot.
Any advice?
Thanks in advance.
It's a vinyl liner pool, and you have to really zoom in to see it ... look at the white "grout" lines and notice the discoloration. I looked around the rest of the pool and found a couple other similar areas that had the same discoloration. Here's another pic on the opposite side of the pool:
You can see the discolored on the partial tiles along the seam.
Thinking it could be algae, I started a SLAM on Saturday. My tests (using TF-100 test kit) from Saturday morning were:
FC 5.0
CC 0.0
pH 7.7
TA 90
CYA 40
I added liquid chlorine to raise the FC level to 16 (after reading some more, I realized I should've lowered my pH first). I brushed and vacuumed to filter on Saturday and restested/added chlorine every 1 to 2 hours to keep up FC. I did an OCLT Sat night/Sun morning, but obviously messed up the Sat night test because I had 13.5 Sat night and 15.0 on Sat morning ... I blame drop counting fatigue on the Saturday night test.
On Sunday, I continued to test and keep FC up at 16, and brushed and vacuumed again. Performed the OCLT test, this time testing twice on Sunday night - 16 FC, and twice this morning - 15.5 FC and 0.0 CC. So I think I passed the chlorine loss test.
However, looking at the hot spot in my pool this morning, I can vaguely see the discoloration starting again.
Could this be mustard algae? With the little chlorine loss and no CCs, I'm at a loss. Starting this week, we've started to have a lot of leaves fall in the pool, so I'm constantly emptying skimmer baskets and skimming the pool. But if from the leaves, I wouldn't expect the discoloration to keep forming in the exact same spot.
Any advice?
Thanks in advance.
