I service a 15000 gallon pool with sand filter that was just backwashed 3 weeks ago, the filter runs 7 hours per day with water temp around 75_80, chlorine level 3, pH 7.5, stabilizer 50 and 0 phosphates yet I'm getting some green algae in the shallow end. What could be causing it? A fellow pool guy told me if the prior pool person used a lot of algaecide with copper in it that could be the reason. Your thoughts or suggestions would be appreciated. Thank you.
Why am I getting green algae
- Thread starter Wwood2016
- Start date
At a CYA of 50, your minimum FC should be 4, but I would shoot for 6.
3 is too low and you may have algae.
3 is too low and you may have algae.
Welcome to TFP.
Is this pool a public pool? TFP guidelines apply to residential pools, and public pools are usually restrained to city/town/state requirements.
With that said, you are getting algae due to improper sanitizer levels. With a CYA of 50ppm, your minimum FC level for proper sanitation would be 4ppm, with a daily FC target of 6-8ppm.
Copper based algaecides (or any algaecide for that matter) do not promote algae growth.
Please let us know if this is a public or residential pool, and if it is indoor or outdoor.
Also, a complete set of test results including FC, CC, pH, TA, CH & CYA would be extremely helpful to get an idea of the water balance.
Previous use of algaecide with copper in it would directly not lead to later algae problems. It could most certainly lead to liner/surface staining and green hair on blonde pool users, however.
That FC level is actually too low for the current CYA level. Our methods here at TFP are primarily focused on the established relationship between CYA and FC level and the proper ratio that must be maintained to keep a pool sanitized. The [FC/CYA][/FC/CYA] chart spells out those requirements. Any time the FC drops below the minimum FC level for a given CYA level, there is a chance algae can get started. For 50 ppm CYA, 4 ppm FC is the minimum.
Other considerations:
How is the pool chlorinated. Manually chlorinated pools must have slightly higher minimum FC levels as the delivery of chlorine is not as consistent as it is with a SWG chlorinated pool.
How often is the pool brushed? It must be done on the entire pool at least weekly. Pool robots and automatic cleaners can help, but there is no substitute for manual brushing.
Check out some further articles in Pool School to become familiar with the methods we teach here.
ABCs of Pool Water Chemistry
SLAM Process
That FC level is actually too low for the current CYA level. Our methods here at TFP are primarily focused on the established relationship between CYA and FC level and the proper ratio that must be maintained to keep a pool sanitized. The [FC/CYA][/FC/CYA] chart spells out those requirements. Any time the FC drops below the minimum FC level for a given CYA level, there is a chance algae can get started. For 50 ppm CYA, 4 ppm FC is the minimum.
Other considerations:
How is the pool chlorinated. Manually chlorinated pools must have slightly higher minimum FC levels as the delivery of chlorine is not as consistent as it is with a SWG chlorinated pool.
How often is the pool brushed? It must be done on the entire pool at least weekly. Pool robots and automatic cleaners can help, but there is no substitute for manual brushing.
Check out some further articles in Pool School to become familiar with the methods we teach here.
ABCs of Pool Water Chemistry
SLAM Process
This is a private residential pool without a SWG therefore it is manually chlorinated and brushed weekly. Thank you for your help