I have 25ft round ABG vinyl pool. I have had it for 40 years. Discovered TFP about 15 years ago, saved much money and great water with few problems. Every year about this time I get what I call green dust algae. It is not slimy, but like a green dust on the bottom and around the cove area. I never have let the FC drop below 5 this season and the CYA has been 35-40, all other numbers very good. In the past, I would SLAM and the problem was gone. So I used LB to bring FC to 13 to 15 and kept it there for a week. I forgot to mention that the CC was 0.5 and then to 0 soon after the start of the SLAM. I have been running the sand filter24/7 since. The FC only drops 2ppm overnight. The green dust remains. I also took out my pool ladder for 3 days to make it easier to vacuum and brush. I am going to order a DE substitute from Amazon to add to my sand filter to see if this will clear the water and get rid of the green dust. I think the product is called Jack's Magic Filter Fiber. Any thoughts or suggestions?
Green dust algae
- Thread starter banjomarsh
- Start date
Me again, I check my pH with a meter instead of drop test, is the meter reading accurate during SLAM? Does not seem to be affected by the high FC levels.
- Jul 17, 2019
- 3,731
- Pool Size
- 13000
- Surface
- Plaster
- Chlorine
- Salt Water Generator
- SWG Type
- Pentair Intellichlor IC-40
The meter is not impacted by FC>10 like the drop test. With that said, your pH should have no bearing on cloudiness or algae. Since you are mentioning green dust and are losing >1 FC overnight, I'm almost positive you have active algae somewhere.
- How are you testing your water and how confident are you in the 40 CYA number?
- If 40 CYA is accurate, 16 is your SLAM FC
- I would be looking for hidden algae in the stairs, skimmers, light, drain, cover, etc.
- How are you testing your water and how confident are you in the 40 CYA number?
- If 40 CYA is accurate, 16 is your SLAM FC
- I would be looking for hidden algae in the stairs, skimmers, light, drain, cover, etc.
Very confident in the numbers, use the big test kit with new components (TL-100). The CYA number is subjective as you well know, but I am sure it is 40 or less. I may SLAM again because the water is not sparkling clear as usual. The back pressure on the filter only went up about a # after a week of constant running is why I will try the filter aid when it is delivered.
Pictures?
It might be mustard algae, which requires a mustard protocol.
www.troublefreepool.com
It might be mustard algae, which requires a mustard protocol.
Mustard Algae
Today We are going to show you how you can get rid of mustard algae in your pool. By following the steps in this guide and with no expensive chemicals.
www.troublefreepool.com
I believe you are correct, mustard algae fits the symptoms of my problem. I hope I can find some more Liquid Shock to SLAM with, the local places have been out.
- May 3, 2014
- 58,771
- Pool Size
- 6000
- Surface
- Fiberglass
- Chlorine
- Salt Water Generator
- SWG Type
- Pentair Intellichlor IC-40
Yes Menards, checking there today (Sat). FC at 16 to 18 for 48 hrs with CYA at 35-40. (just barely can see the black dot @ 40). Much improved but not sparkly clear.
Update on Green Dust. It was mustard algae. SLAMed again for 2 days @ 17 to 18 FC. Better but still not clear. Added a product from Amzon called Jack's Magic Filter Fiber to the 150# sand filter, 12hrs later back to sparkly clear. Backwashed filter as pressure was up 5#s. Green water came out. Conclusion: sand filter alone will not catch the mustard. The mustard algae is green in color even when SLAMed to death. Grandkids and myself swam in pool even at these high levels of Free Cl2(no CC) with no complaints or ill effects and no chlorine odor at all. Thanks for all suggestions and God bless.
