Should I slam the pool again.

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A

amati5

Well-known member
Sep 13, 2011
233
So Cal
My pool is clear but I see what seems like black algae on the steps of my pebble tec pool and it's getting worse. My FC won't maintain and keep dropping down to zero after I add bleach or super chlorinate. My CYA is somewhere 70-80 and PH is within range. I had this problem about a month ago. I slammed the pool and got rid of the black algae and FC maintained for couple of weeks but now the problem is back.

I understand that it might be the algae that consumed the FC and last time when I slammed the pool, may be I didn't slam enough to kill all the black algae and it's back and killing the FC. Does it sound like a good assumption?

Also, I use Pool Solutions CYA because I found a good deal on the 25 lbs container, and the dot test shows a good number. My question is, if the dot test shows good number, does it absolutely mean that my CYA is good? I don't know how the test works but just worry that may be the test can be fooled by whatever chemical they have in there.

Thx
 
amati5 said:
My pool is clear but I see what seems like black algae on the steps of my pebble tec pool and it's getting worse. My FC won't maintain and keep dropping down to zero after I add bleach or super chlorinate. My CYA is somewhere 70-80 and PH is within range. I had this problem about a month ago. I slammed the pool and got rid of the black algae and FC maintained for couple of weeks but now the problem is back.

I understand that it might be the algae that consumed the FC and last time when I slammed the pool, may be I didn't slam enough to kill all the black algae and it's back and killing the FC. Does it sound like a good assumption?

Also, I use Pool Solutions CYA because I found a good deal on the 25 lbs container, and the dot test shows a good number. My question is, if the dot test shows good number, does it absolutely mean that my CYA is good? I don't know how the test works but just worry that may be the test can be fooled by whatever chemical they have in there.

Thx
Click to expand...
If you have algae returning it is because you either did not meet all three criteria needed to complete a SLAM, or you are letting your FC levels drop below the recommended minimum for your CYA. I'm willing to bet it is a combination of both.

What test kit are you using? What target FC are you trying to maintain?

Why is your CYA so high? Do you have a SWG?

Dom
 
pabeader said:
I believe the Aquarite is shorthand for an Aquarite SWG.
Click to expand...

Yes, I have SWG. I haven't got a chance to even raised the FC to proper level with CYA, yet except after that one time I slammed the pool with 2 gallon of bleach and the FC level went above the reading chart ( of the basic test kit). I am using the TF-50 kit.
 
domct203 said:
Are you saying your SLAM only used 2 gallons of bleach in your 35,000 gallon pool?

http://www.troublefreepool.com/content/125-slam-shock-level-and-maintain-shockingl

Dom
Click to expand...

Ha ha, just found out about that, too. I forgot to mention but I also used 1 package of dichlor, not sure how much FC it added. So based on the calculator, to raise from 0 to 31 ppm of FC for 35k gallong pool, I need 10 gallons of 10% or 12 gallons of 8.25% (bleach). That isn't too much, is it? When I did the 2 gallon and 1 package of dichlor , FC level looked really high.

Also, not very clear when the pool school mentions I need to get level at least couple of times. Does that mean raise it to 31, let it drop and raise again in several days? I definitely don't have to keep it at 31 for several days, do I?

Thx for your help.
 
amati5 said:
Ha ha, just found out about that, too. I forgot to mention but I also used 1 package of dichlor, not sure how much FC it added. So based on the calculator, to raise from 0 to 31 ppm of FC for 35k gallong pool, I need 10 gallons of 10% or 12 gallons of 8.25% (bleach). That isn't too much, is it? When I did the 2 gallon and 1 package of dichlor , FC level looked really high.

Also, not very clear when the pool school mentions I need to get level at least couple of times. Does that mean raise it to 31, let it drop and raise again in several days? I definitely don't have to keep it at 31 for several days, do I?

Thx for your help.
Click to expand...
Please read or re-read
Pool School - SLAM - Shock Level And Maintain

A SLAM definitely DOES mean that you have to keep FC at the shock level continuously (or as continuously as you can manage given other life commitments) around the clock, for as long as it takes.

Also, what do you mean about FC level looking "really high"? Did you use your FAS-DPD test to actually measure FC? Or did you just use an OTO test and see a stronger yellow than the highest value on the color block?
 
Just OTO test. Will use my TF test kit to test. This is the first time I have to slam the pool in 15 yrs.

While at the store to buy chlorine, I had them check the cya and it was at 40. I know their test is not reliable but I have to retest with my kit again.

I read that black algae came from the ocean. My son used the pool water to rinse his wet suit. Could this be the reason?
 

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The solution is to SLAM you pool. Don't worry where it came from, eradicate it. You are going to need lots of chlorine and extra FAS-DPD reagents so stock up now. TFTestkits.net

Stop using any form of solid chlorine, that Dichlor just drives up your CYA even higher.

Post a full set of test results. Please,let us see real numbers, not "within range"

Turn the SWG off, adjust the pH to 7.2 and set,the SLAM started.
 
Latest test

Cya, 70
Fc, 28
Ph, 7.6
Cc,0
Salt is high, consistent with pool store, 3750. Wonder if this is part of the reason for low Fc before slam.

Black algae seem to slowly disappear as expected. I brushed the area every few hours since I stayed home today. Will do another test tomorrow and add more chlorine as needed.
 
amati5 said:
Latest test

Cya, 70
Fc, 28
Ph, 7.6
Cc,0
Salt is high, consistent with pool store, 3750. Wonder if this is part of the reason for low Fc before slam.

Black algae seem to slowly disappear as expected. I brushed the area every few hours since I stayed home today. Will do another test tomorrow and add more chlorine as needed.
Click to expand...
If the SWG is happy with that salt level you should be fine. Lets stick to the SLAM to rule out organics & "reboot" the pool.

Remember, it's all about Maintain. Don't worry about overshooting your shock FC target a bit to make up for the loss before you can test/add again. I would have put it 2-4ppm higher before going to bed.

Also, check/add FC more than once a day, do it as much as possible, no sooner than 1 hour but not less than twice a day.

You are not done until you meet all three criteria:

1) Water is clear
2) CC =<0.5ppm
3) OCLT pass (<1.0ppm loss)

You'll be amazed at how clear your pool will become.

Dom
 
I guess adding one gallon of bleach should be more than enough to raise 2-4 ppm. My pool has always been clear. Just the black algae on the steps and chlorine kept dropping down to zero. I guess I was using some cheap algaecide and it didn't do anything to black algae.

Just curirous, why shut the SWG off?

Thx
 
amati5 said:
I guess adding one gallon of bleach should be more than enough to raise 2-4 ppm. My pool has always been clear. Just the black algae on the steps and chlorine kept dropping down to zero. I guess I was using some cheap algaecide and it didn't do anything to black algae.

Just curirous, why shut the SWG off?

Thx
Click to expand...
Why are you "guessing" on the chlorine addition? Use Pool Math and it will tell you exactly how much to add, then test to confirm.

Dom
 

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