FC of 3 with CYA over 200-why no algae?

[Flbeachluvr]

I posted previously about my brother in law who follows the traditional pool $tore methods. A few months ago he let me test his water with my Taylor kit and his CYA was 200+ (diluted test) and at that time his FC was a whopping 31 (brown on the OTO test). He will not drain his pool (his pool, his choice) but did back down on the pucks.

I recently retested his water for him and still got the CYA at 200+ but his FC was only 3. My question is, why doesn't he have algae? I thought that his minimum FC based on his high CYA would be in the neighborhood of 15. He does "shock" his pool every weekend with liquid chlorine from the pool $tore. Maybe that's just enough to keep the algae at bay?

Just trying to understand for my own knowledge.

 

[ping]

The extra chlorine does help some and he is following more or less what some pool service companies do. The CYA level is higher than most service companies levels and if the pool ever does develop an algae bloom then it will be very difficult to clear. So far he must be lucky that his pool is very low in nutrients for the algae to grow and/or he is using a phosphate remover.

Just because a pool looks clear doesn't mean it is safe to swim in. With that high of CYA and low levels of FC I sure wouldn't swim in it.

 

[mikemass]

He probably has the faint beginnings of it every weekend. And then before it gets a chance to really take hold he annihilates it with his Liquid Chlorine Shock-a palozza. Sounds like a bomb ticking however.

 

[Flbeachluvr]

Ok, then, that makes sense. Sometimes I think I see faint greenish patches on the bottom of his pool but then they're gone after his shock and brush weekend routine.

 

[domct203]

Ok, then, that makes sense. Sometimes I think I see faint greenish patches on the bottom of his pool but then they're gone after his shock and brush weekend routine.

While it may no longer be visible, the algae (and probably bacteria as well) is still in the water, hence why it shows back up needing to be brushed.

As mentioned, just one slip of a busy weekend without his 'shocking' and that pool will most likely turn green very quickly.

Dom

 

[Flbeachluvr]

Just because a pool looks clear doesn't mean it is safe to swim in. With that high of CYA and low levels of FC I sure wouldn't swim in it.

Believe me, I don't! His lives right next door so I can just use my own TFP managed pool .

 

[aftrshok99]

he annihilates it with his Liquid Chlorine Shock-a palozza.

almost spit my coffee out!!!

 

[Donldson]

I know a guy who manages to pay for a yearly trip to Vegas with his slot machine winnings, sure doesn't mean I am going to him for financial advice. Same with pools. If someone has a pool that they barely take care of but always remains clear I would envy them but sure wouldn't follow their lead.

 

[JoyfulNoise]

What's his CC levels? Does he use any supplemental algaecide products? What kind of stabilized shock is he using? Does he use multipurpose tablets with copper in it?

One thing to remember is that algae is very slow growing compared to bacteria (colony doubling time for algae is about 4-8hrs depending on the species, 30-45mins for bacteria). So water tends to look dull and "off" for a while before it turns green. Green water is really an end-stage algae growth problem.

Finally algae is very susceptible to chloramines. Monochloramine kills algae at a fairly decent rate and some algaecide products (EDTA containing algaecides) are based on the in-situ formation of monochloramine. If his CCs are higher or if he is using stabilized chlorine products with copper in them, then that could easily allow him to ride at lower FC levels.

 

[Flbeachluvr]

What's his CC levels? Does he use any supplemental algaecide products? What kind of stabilized shock is he using? Does he use multipurpose tablets with copper in it?

One thing to remember is that algae is very slow growing compared to bacteria (colony doubling time for algae is about 4-8hrs depending on the species, 30-45mins for bacteria). So water tends to look dull and "off" for a while before it turns green. Green water is really an end-stage algae growth problem.

Finally algae is very susceptible to chloramines. Monochloramine kills algae at a fairly decent rate and some algaecide products (EDTA containing algaecides) are based on the in-situ formation of monochloramine. If his CCs are higher or if he is using stabilized chlorine products with copper in them, then that could easily allow him to ride at lower FC levels.

I don't know what he uses except for liquid chlorine from the pool store and pucks in a floater (not sure what kind though). He also sometimes uses bags of "shock". When I tested his CC I got zero both times. My curiosity was just piqued as to how he has been able to keep the pool looking (at least on the surface) as good as it does for the two years we have lived next to them.

 

[welbo]

I don't know what he uses except for liquid chlorine from the pool store and pucks in a floater (not sure what kind though). He also sometimes uses bags of "shock". When I tested his CC I got zero both times. My curiosity was just piqued as to how he has been able to keep the pool looking (at least on the surface) as good as it does for the two years we have lived next to them.

I know what you are feeling. Being new to TFP, I have some of the same thoughts. My pool looked fine last year, treating with dichlor powder and tri-chlor pucks. I only messed with every few days and sometimes longer.
I doubt the pool was continuously and properly sanitized. Rain probably had a lot to do with why the pool survived the season without a bloom. Plus I don't have any trees or a source of much organic matter that fell in the pool.
I like KNOWING the pool is sanitized. And KNOWING is half the battle.