Algae Battle

[SaltLife]

Hi All, In the past 2 weeks we have received over 12" of rain... rained for 4 days straight then rained everyday for the next week (eastern NC). My pool has been sparkling clear all summer but I didn't give it any attention during those 4 days. On the 5th day I checked it out and there was massive amounts of what looked like dirt in my pool in drifts the pattern of my pump flow. I vacuumed it out raised the chlorine to about 22. It rained some more and we had virtually no sun so I let it be for a couple days. Tested and the chlorine was down to 11, next day it was down to 5. Vacuumed it again (this time to waste) and bumped up the chlorine to 7. This past week I've held the chlorine at about 4 (my kids wanted to swim) and vacuumed once. I vacuumed again today, I can't slam it again until tomorrow night as we are going out of town for 4 days. How do you know when its ok to let the chlorine level drop? My pool has never turned green throughout this process. Its kinda yellow and powdery. My TA is 180 and my CYA is about 40. PH is 7.8

Sorry meant to post this in algae forum...

 

[kcindc]

SLAM=Shock Level And Maintain. You almost have the "Shock" part right, but you need to "Maintain" This means testing and adding chlorine to keep your FC at shock levels for your CYA. You haven't been testing and adding frequently enough to SLAM. At first, you might need to test and add chlorine hourly with decreasing frequency as needed to keep the FC high. While you are SLAMing you should be brushing and vacuuming your pool daily and running your pump 24/7. Also, don't raise your FC to 22, a high FC can cause your equipment to prematurely fail and it can cause your pool liner to prematurely fade.

You should continue to SLAM until you pass ALL THREE of the criteria:

1. Pool is crystal clear (like no more cloudy stuff on the bottom), and
2. You have less than 0.5 CCs, and
3. You passed the OCLT test (don't bother with this until your water is crystal clear)

Before you start, you need to get your PH to 7.2. The PH test isn't accurate when the FC is 10 or above, so get the PH down with acid, confirm that it is down and begin your SLAM.

Once you start the SLAM, you only need to test FC and CC.

Read this to SLAM: http://www.troublefreepool.com/content/125-slam-shock-level-and-maintain-shocking
Chlorine/CYA Chart: http://www.troublefreepool.com/content/128-chlorine-cya-chart-slam-shock
Pool Math to help with calculating chemical additions: http://www.troublefreepool.com/calc.html
OCLT Test: http://www.troublefreepool.com/content/136-perform-the-overnight-fc-chlorine-loss-test-oclt

Once you finish the SLAM, you should try to bring you TA down a bit which is causing your PH to rise high. Don't worry, we can help you with this once you finish your SLAM.

 

[tim5055]

kcindc is correct, what you are calling "SLAMMING" isn't what we call SLAMing at all. You should read the directions on SLAMing your pool in the How To section of Pool School and follow that procedure completely to the end.

 

[SaltLife]

Thanks for helping me out on this. Speaking of the TA, my tap water has a TA of 300 ! After 2 full months it is now down to 180.... does alkalinity have anything to do with chlorine usage? I've used about 20 gal of chlorine so far. Started out with dichlor then switched over to liquid. have put stabilizer in 3x about 12 oz at a time waiting a week then testing. Just ordered more CYA so i can keep testing.

 

[kcindc]

does alkalinity have anything to do with chlorine usage?

No, alkalinity is adjusted so that it buffers PH to keep it steady.

Started out with dichlor then switched over to liquid. have put stabilizer in 3x about 12 oz at a time waiting a week then testing. Just ordered more CYA so i can keep testing.

Are you ordering more stabilizer, or are you ordering more reagent so that you can test your CYA more? If the former, you don't need anymore stabilizer at the moment because you are SLAMing and your CYA of 40 is a good place to be for a SLAM. If the later, you don't need to keep testing for CYA unless you have a) added stablizer and want to check your new CYA level, or b) removed and replaced a lot of water. CYA doesn't get used up like chlorine and it doesn't go away when water evaporates.

Have you been able to get your PH down to 7.2?

 

[SaltLife]

it's the latter (reagents) only had 3 tests in the kit and have had a hard time getting my CYA up. Finally got it to 30 and have been bumping it along trying to get it to 50. My alkaline water is driving me nuts. I try not to add any if I can help it but I have vacuumed to waste a few times and back washed trying to clear out any algae. I also poured a couple cups of bleach into my skimmer and quickly turned off the pump to capture some of the chlorine in the sand tank and let that set for about an hour. I was bragging on how great my pool looked and how simple it was to keep up (though I've spent more in bleach than I thought I would have to). I tested nearly every day and vacuumed at least twice a week, more if we had highwinds/storms and added Chlorine and MA as needed (my ph tends to drift up every day), but alas got slack during all the rain and didn't keep the chlorine up and now I'm paying the price. I'm going to have a friend keep a check on it while I am gone. I bumped my chlorine up to 12 last night and a 10 am it was down to 4 but my water is looking much better. I also added 24 oz of MA last night and my ph was 7.4 this am. going to let my girls swim again today then hit it hard again tonight and in the morning before I leave. I am also stocked and ready to go to add borates when I get back (IF i can get my TA down, MA/aerate/MA/aerate). Ive been studying how but I may need a little clarification before I begin.

 

[kcindc]

I strongly suggest that you get your PH down to 7.2 instead of 7.4 because your PH will rise during the SLAM.

If possible, you need to test and add bleach more frequently. The algae is able to rebound when you let the FC get below shock level. With a CYA of 40, your SLAM FC target should be 16. While you are away, can you at least have someone add 1/2 jug of bleach a day to keep the algae from exploding and making all of your hard work go away? Can you put a solar cover on the pool to protect the FC? I'm afraid that you will come back to a big mess.

Also, with you CYA at 40 your non-SLAM chlorine target is 5. I try to not let my FC get below target level. I always shoot for 2 to 3 higher than my target because:

1. by the time I add more chlorine the next day, my FC levels never get below target.
2. if I miss a day of adding bleach, I don't have to worry about my FC levels getting to or below the minimum.

Don't worry about borates until you pass the 3 SLAM criteria listed in my previous post.

 

[SaltLife]

ok, I don't want to screw this up so I am asking for help once again. 10 am results PH 7.4 FC 4.2 added 2" of water today (kids were playing with the hose sprayer and forgot to turn it off ) I vacuumed to waste and brushed the heck outta the pool. 7pm test results PH 7.4 FC 4.0 CC less than 0.5 TA 150. Going on mini vacation for 4 days, but have someone to test/add chlorine for me. What should I do? Do I need to bring the FC back up to high levels?

 

[jblizzle]

What does the water look like?
Is there any visible algae?
What is your CYA?

How much Pool School have you read? Start with these:
ABCs of Water Chemistry
Recommended Pool Chemicals
How to Chlorinate Your Pool

 

[SaltLife]

KC forgive me for asking the same questions that you answered earlier today, I didn't re-read your post before my last post (way to much on my mind, way to little sleep) The pool is just a little cloudy and there is no visible algae today. I have read pool school and have a pretty good handle on the routine stuff , I use the pool math on a reg basis but as I said way too much sleep, way to little sleep. You guys have been so helpful, thank you so much.