Slow growing green algae despite good numbers!

aegeansoulja

Member
Aug 20, 2020
12
Tarzana, CA
Hi all,

I have been fighting green algae accumulation and proper LSI balance in our pool all summer without success. Any help would be appreciated!
  • The pool water is not green, but green algae is slowly growing on the pool sides despite good FC levels and slamming.
  • I started in mid July (prior to measurements below) by shocking with chlorine and the algae was removed.
  • Then I sought to balance the water by bringing the pH down to recommended levels (I was shooting for 7.6). The algae came back.

I live in the San Fernando Valley in California - temperatures are very high - we've been over 100 all week and the pool water temp is often 82+ Fahrenheit.

My System:
Salt Water Generator system = Solaxx PureChlor 40k --> manufacturer recommended salt levels = 3500-4500 (this is higher than other brands)
Pool Gallons = 8,750
Surface = plaster
Pool has a spa section
New Filter Cartridges - Spring 2020
Pool vacuum= Barracuda MX8 Elite
Normal pool filter duration daily = 7 hours
  • During Shocking: 24 hours (this has been 3rd day of shocking with highest output of SWG)
  • Note: I normally don't shock with the SWG, rather use granules, but have been unable to get to Leslie's Pool Supply so used the SWG.
Water Balance:
  • pH is constantly pushing above 8.
  • Over the month of July and August I have been battling this with Muriatic Acid, but it simply shoots up quickly in a day to 8 without maintenance.
  • I have dumped over 6 gallons of MA into the pool over this time!
Current Fight vs Algae:
In process of shocking, but the algae does not seem to die! I scrub the algae off today. I have also been reading this site regarding LSI, does anyone have any experience with this?:
Pool Dosing and LSI Calculator by Orenda

Here are my measurements over the last month using Taylor 2006-c kit:
Measured DateSalt FCCCTCpHCYATACalcium HardnessAction Description
Saturday, July 18, 2020​
4,200
5.0​
0.4​
5.4​
8.2​
50​
190.0​
290.0​
Tested 11 am. pH and total alkalinity are too high, can cause algae. Stabilizer is low for saltwater pool.
1) Add stabilizer to increase CYA to 65
2) Add 5 Cups Muriatic Acid (over 2 days) to bring down ph
3) Retest Conditions on Wednesday
Sunday, July 19, 2020​
4,200
4.4​
0.4​
4.8​
8.2​
50​
160.0​
290.0​
Added 6 Cups of Muriatic Acid in pm. Added ~1/3 of gallon of stabilizer in am. Turned Salt Cell production to 3/8 (was on 4/8)
Monday, July 20, 2020​
--
4.0​
0.2​
4.2​
8.2​
50​
160.0​
--tested at 10 am. No pH movement from acid yesterday, added another 6 cups today. No increase in CYA despite 1/3 gallon added yesterday. Retest tomorrow.
Monday, July 20, 2020​
--
4.8​
----
8.0​
------
Tuesday, July 21, 2020​
--
4.8​
----
8.0​
------
Wednesday, July 22, 2020​
--
4.4​
----
8.0​
--
150.0​
--Tested @ 8:30 am. Adding another 6 cups of muriatic acid.
Thursday, July 23, 2020​
--
4.6​
----
8.0​
------Tested @ 9:00 am. Added another 6 cups of muriatic acid, then another 6 in late afternoon. Kept pump running til 10 pm.
Friday, July 24, 2020​
--
8.0​
----
7.4​
--
140.0​
--Tested @ 8:45 am and ph was still between 7.8 or 8.0, added a half gallon of MA. Tested again at 10:30 am and ph at 7.4 and TA at 140. will test again in eve (7.8 ish). FC high as left pump running in evening. Turned salt cell to 2/8
Saturday, July 25, 2020​
--
7.0​
0​
7.0​
7.8​
52​
130.0​
270.0​
After 9 am testing, added 6 more cups MA. Will retest ph and FC tomorrow.
Sunday, July 26, 2020​
--
7.2​
0​
7.2​
7.6​
------Added 9 cups of MA in the morning and tested at 2 pm - only down to 7.6! Nuts. Added 2/3 gallon of stabilizer. The pool still has algae grown and the FC is at 7.2. Craziness. Added another half gallon of MA at 2:30 pm!
Monday, July 27, 2020​
--
6.8​
0​
6.8​
7.6​
75​
140.0​
--Tested at 8:30 am. Looking better! Will add 3 more cups MA, add the Perfect Weekly and see if ths algae comes down. CYA is now at recommended levels for Salt Water generator and pH SEEMS to be getting stable. TA is in the upper range of normal. Let's see how this plays out!
Tuesday, July 28, 2020​
--
6.8​
0​
6.8​
7.7​
--
120.0​
280.0​
Saturday, August 1, 2020​
--
13.00​
0​
13.00​
7.7​
--
100.0​
290.0​
Added Perfect Weekly. Scrubbed the algae off the walls of the pool on Sunday.
Monday, August 3, 2020​
4,200
9.8​
0.2​
10​
8.0​
75​
100.0​
280.0​
pH sky rocketed to 8 missing a day for acid. Put in a half gallon of MA. Concerns as algae seems better, but it still present. May need to shock with ChlorBrite. May have to start watching TA from dropping too much lower. The acid is reducing the TA
Tuesday, August 4, 2020​
--------
7.7​
------Letting it ride today and will test pH tomorrow
Thursday, August 6, 2020​
--------
8.0​
--
90.0​
--pH shot up to 8 again after 1 day without acid treatment. Will put in 3 cups MA today. TA is starting to come down with all the acid treatment. Need to start thinking about how to raise that without raising pH.
Saturday, August 8, 2020​
--
11.0​
0.2​
11.2​
7.7​
--
90.0​
290​
Thursday, August 13, 2020​
--
7.5​
0​
0​
7.8​
--
90.0​
--On a schedule of 3 Cups MA every other day (Mon, Wed). Has maintained around 7.8 pH. Algae still accumulating slowly and requires brushing weekly.
Tuesday, August 18, 2020​
4,000
16.5​
----
8.2​
--
90.0​
310​
Left pump on all night on SuperChlor setting to try and get rid of the algae. FC was high, but not high enough to kill. Shooting for 30 FC
Wednesday, August 19, 2020​
--
22.5​
----
8.4​
------Left pump on all night on SuperChlor setting to try and get rid of the algae. Added a half gallon of MA.
Thursday, August 20, 2020​
31.5​
8.0​
SuperChlor now at shock levels. Algae still present. Scrubbed algae off the sides. Added another half gallon of MA.
 

mknauss

Mod Squad
TFP Expert
Bronze Supporter
May 3, 2014
34,741
Laughlin, NV
Welcome to the forum!
You need to follow the SLAM Process. From your data, today you reached a SLAM level FC. Now you just need to maintain it. The pH test is invalid at FC above 10 ppm.
Use liquid chlorine to maintain the FC level of 31 ppm for your 80 CYA. We recommend you turn off the SWCG as it is difficult to monitor the progression of the SLAM Process with it adding chlorine.
Take a read through the SLAM Process article and let us know your questions.
I suggest you read ABC's of Pool Water Chemistry.
 

Texas Splash

Mod Squad
TFP Expert
LifeTime Supporter
That's quite a first post. Wow. :) Hats-off for tracking everything so well. Welcome to TFP! :wave:

full
 

aegeansoulja

Member
Aug 20, 2020
12
Tarzana, CA
That's quite a first post. Wow. :) Hats-off for tracking everything so well. Welcome to TFP! :wave:

full
haha...love the Ned Stark meme. Been going my own way for a while and it's been frustrating not being able to kill this stuff off. I will follow the slam process over the next few days and see if I see improvement. It's been over 31 FC for over 24 hours and still have green spots.
 

aegeansoulja

Member
Aug 20, 2020
12
Tarzana, CA
Welcome to the forum!
You need to follow the SLAM Process. From your data, today you reached a SLAM level FC. Now you just need to maintain it. The pH test is invalid at FC above 10 ppm.
Use liquid chlorine to maintain the FC level of 31 ppm for your 80 CYA. We recommend you turn off the SWCG as it is difficult to monitor the progression of the SLAM Process with it adding chlorine.
Take a read through the SLAM Process article and let us know your questions.
I suggest you read ABC's of Pool Water Chemistry.
Thank you - I will follow the SLAM protocols and keep this thread posted.
 

aegeansoulja

Member
Aug 20, 2020
12
Tarzana, CA
UPDATE: I've held 31 FC for 4 days and my overnight FC loss was 0 this morning and CC measurement was 0 as well. Pool looks clear. I have scrubbed the pool vigorously each day, but there are spots where I can still see a little green (on the edges) that won't rub out, regardless of how hard I scrub. Will see if the SLAM is successful as will start running the normal process and bring the FC back down to normal levels.
 

aegeansoulja

Member
Aug 20, 2020
12
Tarzana, CA
ct any potential hiding spots for algae. For some pools it's a ladder or hollow steps. For others it may be behind a light (niche) or under a drain cover. You might look carefully around that waterfall as well.
Thanks that is helpful. The intake for the skimmer had a bunch of algae coating and some in the light fixture casings. There are a couple of spots that still seem to have a bit of green/brown on the concrete, but it simply doesn't come off regardless how hard I scrub. Not sure if that is algae or just sand/dirt from the beautiful LA air. My overnight loss was 0 and have held FC at 31 for 4 days, will see if that did the trick.
 
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kellyfair

Gold Supporter
Bronze Supporter
Jun 29, 2016
3,212
Tampa, FL
Are you able to scrape any of that off with a fingernail?

Remember, there are three criteria for ending SLAM - CC of 0.5 or less, pass OCLT, and no visible algae.
 

JamesW

TFP Expert
Mar 2, 2011
22,049
That might be iron. Try putting a vitamin C tab on a spot.

Iron and algae can look similar. If you have both, it can be confusing.
 

aegeansoulja

Member
Aug 20, 2020
12
Tarzana, CA
Are you able to scrape any of that off with a fingernail?

Remember, there are three criteria for ending SLAM - CC of 0.5 or less, pass OCLT, and no visible algae.
I was able to get the most of it off the skimmer intake (tile). The places on concrete I've scrubbed and scrubbed. it's like sandpaper so the fingernail doesn't do anything. How does this Crud survive at 31 FC for 4 days?! I'll continue SLAMing for another day/night. ugh.
 

aegeansoulja

Member
Aug 20, 2020
12
Tarzana, CA
Thanks for the tip! I have scrubbed a vitamin c tab on it and left it to dissolve and will report back.
In one area it seemed to clear it up, in another didn't do anything. I kept SLAMing yesterday after intense scrubbing and all night. No FC loss and no CC. One thing I did not do is clean the filters. Is that an absolute must do?
 

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