Do I have algea

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D

debuda

Bronze Supporter
May 16, 2019
107
Los Angeles
I'm not sure if we have an algea problem. We have a pool finish that makes the water look slightly green to begin with and I think it looks more green than usual. The water is completely clear.

Pool chlorine has been desolving really quickly though which is making me think there is algae.

I tested chlorine yesterday got an reading of .5 and added recommended dosage to bring level up to 4. This was 5 pm yesterday. This am it's at 2.5.
I have a swg running at 100% as well.

My numbers yesterday...
21000 gallon plaster with swg
FC .5
TC 0
pH 7.2
CYA Between 50 and 60
CH 310
TA 90
SALT 3200

Should I Slam? Never done it before as this is the first season with pool.

Thanks for you help!
 
Since you suspect algae and have a much higher chlorine demand than usual (supporting the algae theory), I would recommend SLAMing. Call your CYA 60, as we always round up, so your SLAM target is 24 FC.

Do you have one of the recommended test kits? If not, you will need one to test the higher values of FC required to SLAM. Also, post back here if you have any other questions about the process, we're happy to help :)
 
Just an update...
I didn't SLAM yet because I've been waiting for a block of time where I can devote to it. I am thinking to do it this week.
The water is still clear although we are using the SWG 10 hours at 100% and it's not keeping up. I've been adding about 1-2 qt's of chlorine every other day.

Todays numbers...
pH - 7.4
FC - 2.5
CC .5
CYA 60

I brought the chlorine up to 7.5

Do you think if I added more CYA it would stabilize or should I just go for the SLAM and then see if I need to add more CYA?
 
Do not add more CYA. That will simply increase your SLAM level FC.

Why wait on SLAM? If you can test and add chlorine in the morning, after work, and before bed, you are good to go. If someone could add some chlorine at noon, you are golden.
 
Read through the SLAM post and it seemed pretty involved (frequent brushing). I have been pushing it off because of that and kids are swimming daily for their PE :)

Guess I will have to just do it...

Given that the pool is clear I was just going to use the overnight test to determine when I'm done SLAMing. Any other way to determine when it's ready to get back to normal?
 
The three criteria. Crystal clear, CC under 1, FC loss of 1 or under with OCLT.

Kids can swim during SLAM. Just keep FC at or just below SLAM level. Brushing once a day is good but sounds like you do not have active algae on the pool surface?
 
Good to know kids can swim - Thought I have to wait due to high chlorine content.
I do have a few stains that I have noticed. One is for sure not algae - I noticed it after leaves were left to sit for too long. Not sure about the others though.

Took a few pictures...
The long skinny dark one is on a wall and the round one is the one I noticed with the leaves. Hoping they go away with the SLAM as well.
 

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If they are still there after the SLAM, try some crushed up vitamin C in a thin sock. Might be iron.
 
I have been SLAM'ing the pool - Adding a TON of chlorine brought chlorine up to 24ppm based on pool math.
Sunday night was first night. OCLT started at 24 and ended at 14 in the AM. Couldn't believe the drop. Yesterday brought back up to 24 and OCLT this AM was 19.5. Definitely getting better. I checked mid day today and was 21.5.
I have been running my SWG during the daytime and turning it off 30 prior to testing for the OCLT to conserve a little bit of chlorine...I hope I don't have to make another trip. I can't believe how much cholorine I've been running through.

Quick question - I've been leaving the solar cover on. Does it matter if it's on or off?
 
The solar cover being on will trap the CC. Best to remove it during the day when the sun shines on the pool.
 
Day 3 chlorine demand is dropping...this mornings test was 21ppm so a drop of 3ppm overnight. I am hopeful that I will pass the test tonight. Water has defenitely become "crystal clear" even though I thought it was clear before I began. So cool to see the progression!

I added a little more chlorine this morning to bring it up to 28ppm thinking that it will help clear it out a little faster...hopefully not too bad for equipment and pool surfaces.

One more question about the solar cover...will I see increased algae growth with cover on? Are there any precautions to take (like higher chlorine level)?
 
You may want to brush the solar cover while the FC is at SLAM level, or take it out of the pool and clean it. Since it's one of your pool surfaces there could be algae on the cover. Brushing breaks up the biofilm and allows the FC to kill the algae.

No need to raise FC above SLAM level. This is one of those cases where more is not always better. Having FC 4 above SLAM for a short period of time is not likely to hurt anything, but the higher your FC, the less it's protected by CYA so you will loose FC faster to the sun. There is no evidence I've seen that going above SLAM kills algae any faster, you will likely just loose more FC to the sun.

Stick to the SLAM process and have lots of POP (pool owner patience) and you will pass your SLAM soon :)
 
aeh0603 said:
You may want to brush the solar cover while the FC is at SLAM level, or take it out of the pool and clean it. Since it's one of your pool surfaces there could be algae on the cover. Brushing breaks up the biofilm and allows the FC to kill the algae.

No need to raise FC above SLAM level. This is one of those cases where more is not always better. Having FC 4 above SLAM for a short period of time is not likely to hurt anything, but the higher your FC, the less it's protected by CYA so you will loose FC faster to the sun. There is no evidence I've seen that going above SLAM kills algae any faster, you will likely just loose more FC to the sun.

Stick to the SLAM process and have lots of POP (pool owner patience) and you will pass your SLAM soon :)
Click to expand...

Ha! I think i have a case of POI (pool owner impatience).
You are so right about the chlorine loss. All the extra chlorine has dissipated already.
I thought about brushing the cover but too much work. I've deliberately brushed it against the coping when rolling with the hope that it will remove any film. Since I've been making progress I am going to try to stick with the nighttime covering and if I dont see improvement in might just get rid of it.
I'm hoping I'll pass the oclt tomorrow...
 
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