Algae came back again

Rapmon23

New member
May 21, 2022
3
Phoenix, AZ
Pool Size
15000
Hello, I have about a 15,000 gallon Pebble Tec play pool, water is clear however I noticed green algae on the steps and walls. Test results as follows:
FC: 1.35
TC: 1.35
pH: 8.1
TA: 71* adjusted due to effect of CyA
CH: 379
CyA: 207
Iron: 0
Copper: 0.1
Phosphates: 1081
TDS: 3200

I was advised to brush the pool, put 1 quart muriatic acid in with pump running (I also have a robot vacuum), then an hour later put 4 bags power powder plus 73 shock. I did this and for several days no longer had any algae and the water was clear. Note: I float 3 to 4 chlorine tablets. However, today (about a week after the first algae outbreak) I noticed green algae again.

After looking at the FC:CyA chart on here I understand due to my high CyA levels, I need to drain/refill but since it's already reaching 100+ degrees in Phoenix I should not do so due to risk of damaging the pool.

What should I do? Is there any way to drain/refill or do I have to wait until after summer?

Would a phosphate remover help? I've read mixed reviews on those.

Any help is greatly appreciated!
 

Bperry

Gold Supporter
Aug 20, 2020
1,847
Knoxville, TN
Pool Size
27000
Surface
Plaster
Chlorine
Salt Water Generator
SWG Type
CircuPool RJ-60
Hello, I have about a 15,000 gallon Pebble Tec play pool, water is clear however I noticed green algae on the steps and walls. Test results as follows:
FC: 1.35
TC: 1.35
pH: 8.1
TA: 71* adjusted due to effect of CyA
CH: 379
CyA: 207
Iron: 0
Copper: 0.1
Phosphates: 1081
TDS: 3200

I was advised to brush the pool, put 1 quart muriatic acid in with pump running (I also have a robot vacuum), then an hour later put 4 bags power powder plus 73 shock. I did this and for several days no longer had any algae and the water was clear. Note: I float 3 to 4 chlorine tablets. However, today (about a week after the first algae outbreak) I noticed green algae again.

After looking at the FC:CyA chart on here I understand due to my high CyA levels, I need to drain/refill but since it's already reaching 100+ degrees in Phoenix I should not do so due to risk of damaging the pool.

What should I do? Is there any way to drain/refill or do I have to wait until after summer?

Would a phosphate remover help? I've read mixed reviews on those.

Any help is greatly appreciated!
You need to switch to using liquid chlorine instead of those tablets and powdered shock.

Do you have your own test kit? If not, you would need to get one as you can’t trust pool store testing to be accurate. Maybe you don’t actually need to drain (but if you’ve been using pucks for a long time your CYA might actually be that high).

The TF-100 (tftestkits.net) or the Taylor K2006C (amazon) are the only two test kits TFP recommends.
 
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Rapmon23

New member
May 21, 2022
3
Phoenix, AZ
Pool Size
15000
Thank you for the info and the quick reply! I will get one of those test kits--I've been getting by with strips (have only had the pool for about a year so far) and these latest results were from the pool store.

Also, that makes sense I should use liquid chlorine which doesn't contain CyA instead of the tablets which are raising my CyA level. I've been hesitant to switch because the tablets seem much more convenient. What is wrong with that powdered shock? I'm pretty sure it is not stabilized.
 

Mdragger88

Bronze Supporter
TFP Guide
Jun 1, 2018
5,818
Hernando, Ms
Pool Size
26000
Surface
Vinyl
Chlorine
Salt Water Generator
SWG Type
Intex Krystal Clear
Phosphates aren’t your problem -
Not following the FC/CYA Chart is.
At cya levels above 100ppm it is almost impossible to eradicate algae & it’s extremely impractical to maintain adequate fc levels.

You will very likely need to exchange some water to get that down so u stand a chance in the fight & can do the SLAM Process.
When u get your kit in you will need to do the diluted cya test if the 1st test reads 90ppm or above. Step 8👇
Then u will have a true idea of really how much water you need to exchange.
Here’s some info on safe draining methods so u can be ready once u have reliable data. 👇

You need to determine how you will chlorinate your pool daily going forward After you get this cleared up or you will be in the same boat again before long if u continue with the stabilized tabs & products.
Cal hypo doesn’t add cya but it adds calcium which also builds up & can only be removed by exchanging water.
Liquid chlorine or a salt water chlorine generator are recommended.
Here’s some info on that👇
To keep things from getting any worse until u can really tackle it when your kit comes u can add a gallon of liquid chlorine daily. Pour it slowly in front of a running return & brush the area.
 

compren

Member
Apr 9, 2019
11
Spring, TX
You're probably gonna have to suck it up and drain some of that pool. Either that or stick a hose in it running for 24-48 hours to get some fresh water in there. CYA just renders your chlorine ineffective. I learned the hard way as well.

As an FYI, I use a combination of pucks and liquid chlorine. In the summer, for my pool (23,000 gals), I use 4-6 cups of liquid chlorine daily, and 2 pucks installed at the beginning of each week in my chlorinator. I use the pucks just in case I forget to add chlorine. My CYA climbs, but it climbs slow enough that it doesn't become an issue. In the winter, I switch to 4 cups daily of liquid chlorine, zero pucks. Sometimes I can get away with just twice a week liquid chlorine in the winter and still maintain a clean, sparkling, pool.
 

Rapmon23

New member
May 21, 2022
3
Phoenix, AZ
Pool Size
15000
Appreciate all of your help!

I've ordered the test kit, and am looking into buying a submersible pump to do the water exchange per the article you linked to hopefully avoid any damage to the pool. Then going forward I will use liquid chlorine. Thank you all!
 
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Bperry

Gold Supporter
Aug 20, 2020
1,847
Knoxville, TN
Pool Size
27000
Surface
Plaster
Chlorine
Salt Water Generator
SWG Type
CircuPool RJ-60
Appreciate all of your help!

I've ordered the test kit, and am looking into buying a submersible pump to do the water exchange per the article you linked to hopefully avoid any damage to the pool. Then going forward I will use liquid chlorine. Thank you all!
Take a look at the salt-water-chlorine-generator (SWCG). After a while lugging those chlorine Jug’s around gets kinda old and so the generator is nice that it adds it for you.
 
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