Battling with Algae

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dandan74

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Aug 12, 2008
6
My pool started showing algea growth on the wall and the bottom. I shocked it a couple of times using bleach and never able to completely get rid of it. Maybe I didn't shocked it high enough.
I restarted the battle yesterday. I poured 10 gal of 6% bleach into my 14000g paster pool. I guess the FC level was fairly high already though I didn't know how much. I constantly shocked it a couple of times using liquid chorline and bleach last week. I tested the water last night:
FC: 33
CC: 6
PH: unknown (forgot to test it before shock0
CH: 450
CYA: 60

I tried to test it this morning but it didn't worked out something.
Got some feedback from the forum and re-tested this afternoon:
FC: 30
CC:0.5
CH:450

Am I doing the right thing? According to the CYA chart, 30 is encough to kill the algea.
But I can still see algae on the wall and steps. I tried to blush really hard but it seems that algae is hiding in the corners here and there. Also, the wall is a bit rough due to the age of the pool (30 years). What should I do now besides keeping the FC high? Will the FC eventually kill all the algea even if I couldn't get to them with brushing? Is my CH too high?
 
Re: Battling with Algea

Hi there. Okay let me start off by asking that you update your profile (go to User Control Panel) and put your pool equipment and specs in your signature, that way you don't have to retype them and we don't have to search for specifics. :whip:

Your shock level for a CYA of 60 is 18. So shocking to 30 and above :shock: is for Mustard and/or Black algae. Routinely shocking for extended periods at that kind of level could damage some pool surfaces, especially if your other numbers are not balanced. You could create a corrosive situation. So you should try to know what your dealing with and then handle it appropriately, but always know all your test results before you start dumping in chems.

Over time, if you maintain shock level and if you brush constantly with an appropriate brush (for a plaster pool), you will defeat the algae and the stains left behind will fade. For Black Algae, which is especially tough to deal with.... it's got this tough outer shell that protects the inside from chlorine. With a plaster pool and an old surface, you may have to consider resurfacing or acid washing, but I don't know much about that or if it would apply to your situation.

But with persistent tough algae, like Black Algae, You HAVE to keep brushing at it to remove the "heads" so that the chlorine can get to the inside and kill it. So just shocking now and then will not get rid of it. Also, it's never a good idea to just dump in 10-15 gallons of bleach without testing first. You could cause serious damage to your pool, just a note of caution for the future.

Can you describe your water and the algae? Is it green looking, black looking dots the size of a pencil eraser? Smallish, black looking algae is probably black algae. Mustard tends to grow in the shady side and up the walls, looks tan or light brown in color and can brush away but return in the same spot, even when the chlorine is at a good level, that's why the shock level for Mustard is higher than regular shock level. That's also why running with a higher level of FC chlorine for an extended period is necessary to keep it from returning. Every situation can be unique.

Lastly, if you test routinely, and keep your water in balance, you should rarely if ever have to shock. Keeping the minimum amount of FC at all times, in a properly balanced pool, will prevent algae from happening in the first place. So keep reading Pool School and familiarize yourself with the articles there especially about defeating algae.

Good luck, we're here to help.
 
Re: Battling with Algea

Dan,

The guy who is the genius behind all the BBB principles taught here used to say this all the time....(don't be offended)

"Your pool did not get the way it looks overnight. Do not expect to change it back overnight"

That's when I first learned that clearing an algae laden pool is a process....not an event. That process can vary quite a bit but a lot of it depends on how judicious the pool owner is at testing and applying chlorine in a timely manner.

Use Jason's Pool calculator (in my sig) to calculate your dosages more carefully and keep your FC at the recommended level and the algae will clear....it'll take some time.

There is a wealth of information in Pool School that will answer most of your questions. We'll help clarify all of them as you go.
 
Re: Battling with Algea

The water is clear. The only visible algae is on the surface of the wall/bottom where it becomes a bit rough due to the age. I brushed pretty hard but never seemed to get rid of it. The color is green. I thought the reason was that my shock level was not high enough. That's why I try to make it right this time. I will try to update the profile tonight. Another question:
According to the CYA chart in your signature, the shock level of CYA 60 is 24. How did you come up with 18?
 
Re: Battling with Algea

I was looking at the Pool Calculator recommendation, sorry for the confusion. You can go ahead and shock to 24, won't hurt anything. But the key to getting rid of that kind of persistent algae in corners, etc. is brushing... the FC of 18 will also work, maybe slower? But you have to keep brushing, with a really good brush. I think Stainless? But I hope we can verify that (EVAN?)....since your plaster is old.

Also what is your filter run time? Sometimes you can have a lack of circulation....all the chlorine in that area of the corners, or wherever, can be consumed, leaving pockets of 0 FC. By keeping the circulation and shock level consistent it can kill the algae better. That's why we recommend running the filter 24/7 when dealing with algae and brush, brush, brush!
 
Re: Battling with Algea

Something stuck to the walls that is green and that doesn't come off with brushing nor fade or discolor at high chlorine levels? This sounds like maybe this is a metal stain, not algae (if it were black, then it could be black algae, but green algae doesn't usually stick that strongly to pool surfaces and will usually bleach out to light gray at high chlorine levels). Why do you think this is algae? You could be right that it's algae if it's mostly in corners you can't reach easily and where the circulation may be poor. It's just odd that it doesn't bleach out -- the chlorophyll in green algae is rather easily bleached by chlorine to no longer be green. Perhaps it's formed a very strong biofilm.
 
Re: Battling with Algea

Thanks Richard!

Richard is right, if routine shocking/brushing isn't getting rid of it.....when you have a chance you can take a chlorine tablet or puck, if you have any, and rub it on the "algae" firmly with your fingers, and if they fade then they are organic. If they don't fade, try taking a vitamin C tablet and rubbing it on the green stain...if they fade, they are metal stains and you will have to try to remove them using the absorbic acid treatment.
 
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