Chlorine levels after bout with mustard algae

Apr 7, 2010
23
Hey Guys and Girls,

Quick question. Just got done battling with mustard algae. I have a 15K gallon pool, underground, with de filter, running filter 24 hrs. Thursday, I brushed the entire pool, added 16 ounces of black algae killer, and 4 1lb. bags of shock. Friday, approximately 18 hours after initial treatment, I checked the FC level and it was at about 5 ppm. Vacuumed the majority of the now gray algae to waste, backwashed filter thoroughly, brushed the entire pool again, and added 2 more lbs. of shock. Saturday, checked FC level and it was above 5 ppm. Brushed again and turned on polaris for good measure. Sunday, brushed pool again and added clarifier for good measure. Everything looks good, water clear, no debris on the floor or sides, no sign of algae, AK is at 120 and Ph is at 7.5. Now my question: I checked the FC level today and it is at 2-3 ppm, but my TC is still at about 5 ppm. What do I do to get the FC equal to the TC? I'm not sure I should shock it more since the TC is already at 5 ppm. Maybe add chlorine free sanitizer?
 
You may have just gotten lucky. I'd go buy a lottery ticket if I was you. Without knowing the CYA level, there's really no way to determine what the minimum FC should be, nor what the sustained "shock level" needs to be to eliminate that CC. Have you read Pool School?
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Hey Richard, I read pool school about two years ago. I haven't really had many problems with my pool since I got it with the house three years ago. So, there is no way to know how to bring my CC down without knowing CYA? Hey frustratedmom, active ingredient is copper. It works on both black and yellow algae.
 
Read Pool School again, time for "summer school refresher...." lol

I have killed every form of algae with just chlorine.

I detest copper in pools, sorry I'm a bit biased ;-P

What kind of surface is your pool? Copper can cause staining (and green hair.)

What is the active ingredient in the 6 bags of "shock" you added? If it was Dichlor, you added CYA...

Assuming the "conditioner" was 100% Cyanuric Acid (some brands aren't) your CYA level is approximately 30 (if the level was zero when you added it)

There really would be no point in adding "non-chlorine sanitizer" at this point. Some simply increase the CC reading, and simply put sunlight and Free chlorine oxidize CCs. Assuming you are shocking to the proper level (with liquid chlorine....)

Edit: What are you testing with? Or are you relying on Leslie's?
 
Vinyl surface. I'm using power powder plus from leslies that has calcium hypochlorite. My pool tester is the DPD from leslies. I believe it was above zero when I added the conditioner. I went looking for the print out, but I can't find the darn thing now. Thanks for your replies. At this point, should I just let it go to see if it equalizes?
 
No, I wouldn't just let it go. With the DPD test how do you know if you have EVER reached the correct shock level? It only goes up to a FC of 5, and with the "dilution method" 10. If your CYA is 30, proper shock level is 12. You need the FAS-DPD test.
 
It is impossible for the chlorine to be at the same level for that many days without adding any. The sun will always consume some. Likely it is just too high for your kit to measure accurately enough.
 

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Weird, but I checked the CH level this morning and both FC and TC are measuring between 3 ppm. I guess it's okay now? Blizzle, I meant it wasn't being consumed by the algae like before. I previously added two 1 lb. bags of shock and by the next day I had 0 CH reading. Now it's holding the CH.
 
What is your CYA level? A FC of 3 may not be high enough to prevent algae from starting ... assuming that you actually completed the shock process given you do not have the ability to test accurately enough.
 
Not sure, but when I opened the pool a month ago I added 4lbs. of leslies conditioner. I should have been enough to bring it to acceptable range based on leslies test. Side note, I've been using phosfree for about 2 weeks. Is this better than using algaecide or should it be used in conjunction with?
 
I'm still new here, but it really seems like you need to head over to Pool School and do some reading. You also need to get a good test kit so you can see what is going on with your pool.

There is no point just throwing chemicals into the pool without understanding why. Trust me, I was the same way when I came to this site. Since then, I have "seen the light."
Follow the procedures in Pool School and you'll be in great shape in no time. :whoot:
 
PhosFree is a complete waste of money. And pool store recommended levels are different than ours and their testing is not good. You have to pick who you are going to listen to so everyone is not wasting their time.
 
I'm pretty well versed with the pool chems. Mustard algae is a pain and a whole different monster. I don't have a FAS-DPD tester, so I have to go to leslies for that. I don't typically have problems with my pool. It seems my chlorine has stabilized and it seems the mustard algae is gone. Leslies has a guarantee on the phosfree to be algae-free, but they said I can use this in place of regular algaecide. They said I can return it if it doesn't work, which I might do.
 
Leslies does NOT use a FAS-DPD test ... they likely use the DPD which is not accurate enough ... plus taking the time to travel there alters the chemical make-up in the water.

Both PhosFree and Algaecide are not needed if you maintain adequate chlorine that depends on your CYA level. If you want to spend the extra money, that is your choice. It is becoming pretty clear that you are not interested in following the methods we teach.
 
Not that at all, blizzle. Just looking for advice from others that know. I guess I will try to return the phosfree. I bought it against my better judgment. I'm not going to be able to get a fas-dpd tester by today, so I will have to take it to leslies to get tested. Have to go there to return the phosfree anyway. Anyway, thanks for the responses.
 
mrice20hd,

You can take care of your pool the Leslie's way; phosfree, algacide, and what ever else they want to sell you, or you can abandon Leslies and learn to take care of your pool with the methods taught here.

It will take some research on your part, but in the long run you will have a pool that is in better condition than any pool that is maintained with the pool store method.

Start over in Pool School and never look back.
 

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