pool just turned green

[63john]

My 16,000 IG gunnite pool has in last few days been turning cloudy and we were hit here in SE the last 2 days two days with steady rain just stopping today. Using the just arrived TF - 100 kit I have since the rain started lite green pool water sorry no pic but looks similar to pic on pool math page. Also cant see 2 drains at 7 feet deep end. Today the pool numbers are :

FC =0
Alkalinity 120 : 2 drops R 0007 then 5 drops R 0008 turn green then 12 drops R 0009 = 120
Chlorine drop test after one heaping scoop R 0870 in 10 ml : No pink so couldn't do CC
Ph test : 5 drops R 0014 : 7.4 - 7.6
calcium H : 125 ( 10 drops R 0010 then mix, 3 drops R 0011L = lite purple no Red then 5 drops R 0012 before turn blue )
CYA test ; 30

Pool math table says

To get from 30 to 50 CYA add either 43 ounces CYA powder or 111 oz liquid stabilizer and also to boost FC from 0 to 12 add 284 oz chlorine 8.25 % bleach

Does the above sound realistic to begin a SLAM? Any comments appreciated thanks realize will take a few days to see effect and begin to clear the green. Also have some black algae spots around top pool edges which have tried to scrap off but little success.

Thank you all

 

[AimeeH]

If you're proceeding to SLAM which it clearly sounds like you need to, I wouldn't raise CYA to 50. Leaving it at 30 is going to be easier for you. I'd try lowering PH a tad wit muratic acid to 7.2 them proceed to shock level for your CYA of 30 and keep at it until you pass all three tests. Brush often

 

[63john]

Thank you AimeeH, the three tests are OCLT, CYA and the other is ? thanks ( my family roots began in near Inman SC about 25 miles from Spartanburg beautiful southern cities.)

 

[Kiss4aFrog]

Until you're done with the SLAM that 30ppm CYA is a very good number to stay at.

Three tests: CC is under .5, the water is clear and you pass the OCLT. Pump and filter 24/7 and brush till your arms fall off. At least once a day

 

[Kiss4aFrog]

A little copy paste from "Pool School" above: "SLAMing your pool is the best way to eliminate algae, sanitize your pool and get your water crystal clear. If you have algae, or the CC level is above 0.5, or the free chlorine (FC) level is zero, you should SLAM the pool. You cannot do this overnight...it often takes several days to see it completed...no shortcuts. If you are maintaining proper FC levels there is no need to SLAM (or shock) weekly, or on any other regular schedule."

The other thing is to remember it's a matter of MAINTAINING that high level of FC and not letting it drop and than raising it up again. If you maintain your FC high at the SLAM level and hold it there by testing and adding often your SLAM will go quicker and be cheaper to do. At the beginning you might need to test every hour or every other for the first few times. As the SLAM progresses you will see you can test and add less often to hold the FC at the proper level.

 

[AimeeH]

Until you're done with the SLAM that 30ppm CYA is a very good number to stay at.

Three tests: CC is under .5, the water is clear and you pass the OCLT. Pump and filter 24/7 and brush till your arms fall off. At least once a day

Well not until both arms fall off because that would put a stall in the process while trying to figure out how to brush with your feet

But in all seriousness I'm a huge advocate of brushing and then brushing some more. I've found algae in the tiniest of cracks and crevices like behind the skimmer wall plate as well as inside it. I finally got a kitchen brush and put the kids to work on some of those areas when in the pool.

Algae does not like being brushed.

 

[63john]

thanks Kiss4afrog, when you say "adding often" you are referring to "bleach or Liquid chlorine" correct ? Would it safe to add the same amount 284 ounces bleach everyday until see progress ?

 

[AimeeH]

The goal with SLAM is to keep your chlorine elevated at shock level for your CYA.

Pool School - Chlorine / CYA Chart

Until you pass all three tests as mentioned above. So you want to add liquid chlorine (bleach same thing in different concentrations) as often as necessary to keep it at shock level. Three tests.

Clear water
CC of .5 or less
Overnight chlorine loss of 1 or less.

 

[63john]

Thank you AimeeH one last Question is it better to either replace or wash the 4 filters before the SLAM begins (with all the bleach everyday going through the 16,000 gallon system and I have a spare set of 4 filters), or change or replace filters after a certain # days of the SLAM. ?

My WP was 24 two months ago at prior acid wash, now 28 or just wait till approaches 34? thanks again

 

[Swampwoman]

Hi john. Just a note for after your slam so we don't forget.

Your calcium level tested at 125, which is low for your type of pool. Recheck that after your slam and bring it to range.

Re cartridges, I'm not familiar...but always best to start at clean pressure, then backwash or clean any time pressure raises 25% and to run filter for duration of slam.

 

[63john]

Thank Swampwoman, AimeeH, and kiss4afrog todays test w TF 100 show
FC 5
CC 1 so TC 6
Calcium: 150
CYA 65 which higher than 30 on Sunday 8/13.

Pool water is loosing green complexion and after two days of 3 jugs Great value 121 oz @ 8.25%, see lighter thinner green or more clear near shallow end than Sunday. My Question occurred, "during SLAM and bleaching do I need to add CYA powder to protect bleach during SLAM?" thanks much.

 

[Mr Bruce]

Did you add CYA?

You might want to read the SLAM article a few times, I don't think you are actually SLAMing. Pool School - SLAM - Shock Level And Maintain

 

[Kiss4aFrog]

thanks Kiss4afrog, when you say "adding often" you are referring to "bleach or Liquid chlorine" correct ? Would it safe to add the same amount 284 ounces bleach everyday until see progress ?

Sorry, missed this post. NO, not safe. You need to test and then depending on your results dose with bleach accordingly.
At the beginning of a really bad green monster you might need to test and adjust hourly. As you keep testing you will see that the FC starts to hold longer and you're adding less bleach. It's a process and you have to remember that letting it drop below the SLAM value for your CYA can allow algae to start back up so you're just on a roller coaster. The most important part is to MAINTAIN that SLAM level as best you can and test as often as you can or need to. As a SLAM progresses you will see that you don't need to test and adjust as often and you can keep waiting longer and longer between tests.

Once it's clean and you're used to adding X oz of bleach each day or X +1/-1 so you already have an idea of the average daily dose it's ok to be lazy for a day or two and just dose it but during a SLAM the fastest and cheapest way is to always test and adjust according to the CYA/FC chart and Pool Math. You are only killing the algae off when you are at the high level. Once under it you're only keeping it in check or worst case low enough it's growing back and you just wasted $$$ on that bleach.