I've got a 17,000 in ground vinyl pool. Around May I noticed a few black spots (looked like streaks) in the pool - I thought the pool cleaner drug something around that stained the pool. When I checked my water, my ph was really high (probably close to 8). I added muratic acid to lower ph and continued to add liquid chlorine. I haven't been religious in testing my pool and keeping levels where they should be. My CYA was coming up almost none so I added 4 lbs. The black spot has grown and spread. I did put a puck on the black spot and after leaving it on there overnight, you can see where the puck was (pic attached). My wife took water and a pic to the pool store about two weeks ago - they thought it was black algae and suggested shocking (using cal hypo), adding a couple bottles of black algaetrine and said the CYA was low so they sold us 5 lbs of stabilizer. My ph was also high again so I added more muratic to get it from 7.8 down to 7.2. We added everything and I started monitoring the ph and chlorine closer. my ph seems to keep rising. Since opening the pool in May I have added probably 2 gallons of muratic. Before adding the stabilizer they sold us, I tested and I also showed our CYA was very low - below 30.
So we've been brushing the pool 3 x a day and adding about 3 gallons of 10% liquid chlorine daily (we were out of town over the 4th so my sister in law was doing it - she didn't test the water, just added a gallon in the am, at lunch and in the pm). The spot doesn't seem to be going away - it seems like it has spread to new places. I know black algae is supposed to be very unusual in vinyl pools, but I can't figure out what it is if it isn't that. We do have a black liner.
Latest tests are:
CYA - 50
FC - 18
ph - 7.6 (ph really keeps going up and down) - when we got back in town it was around 7.4 and the next morning it was 7.8.
We have had a lot of rain this year.
The attached pics were taken last night - there is a tree reflection in the water, but hopefully you can see what the spots look like. One pic has the puck spot circled, another one is a close up of that spot.
Help appreciated -
Cory
So we've been brushing the pool 3 x a day and adding about 3 gallons of 10% liquid chlorine daily (we were out of town over the 4th so my sister in law was doing it - she didn't test the water, just added a gallon in the am, at lunch and in the pm). The spot doesn't seem to be going away - it seems like it has spread to new places. I know black algae is supposed to be very unusual in vinyl pools, but I can't figure out what it is if it isn't that. We do have a black liner.
Latest tests are:
CYA - 50
FC - 18
ph - 7.6 (ph really keeps going up and down) - when we got back in town it was around 7.4 and the next morning it was 7.8.
We have had a lot of rain this year.
The attached pics were taken last night - there is a tree reflection in the water, but hopefully you can see what the spots look like. One pic has the puck spot circled, another one is a close up of that spot.
Help appreciated -
Cory
