Brand new to SWG. Low FC. High TA. Problems with algae

jenjy

New member
Jul 15, 2021
4
Southern Oregon
Hi there!

Found this site last week and now I feel like I might have a shot at understanding my pool!

Just received my TF pro test kit and completed the weekly testing checklist.

My numbers are:
FC: 1.5
CC: .5
so, TC: 2

Calcium: 440 ppm
TA: 280
CYA: 70

20k gallon pool
Intellichlor IC20 set at 2% sanitizer output
3,000 ppm salt

We had the pool installed two years ago, and used chlorine tabs and liquid chlorine until a month or so ago. I have been using a pool service company but still feel like I am chasing a constant algae problem. I am assuming this is because I have low chlorine? I have been completely ignorant of my system up to this point as I received no training and felt completely overwhelmed...hence the pool service company. I am tired of spending a fortune and still having stress. This site is amazing. Thanks in advance.
 

JohnT

Admin
Mod Squad
TFP Expert
Apr 4, 2007
10,031
SW Indiana
Pool Size
21000
Surface
Vinyl
Chlorine
Liquid Chlorine
This FC/CYA Chart will tell you where your FC should be. For 70ppm CYA you you should be aiming for 5ppm FC and never less than 3ppm. If your water is currently clear, you can just turn the SWCG percentage up. Not sure you are really at 2% though. Try something like 70% and see what happens. If the water is green, a SLAM Process is probably warranted.
 

jenjy

New member
Jul 15, 2021
4
Southern Oregon
Water is currently clear. Turned the SWGC up to 80% (had the option of 60 or 80). How long should I wait before I test FC again? Is it "normal" to keep the percentage in the higher range?
 

Newdude

Gold Supporter
TFP Guide
Jun 16, 2019
10,371
NY
Hey Jenjy and Welcome !!! Here is where we shamelessly plug for you to fill out your signature. When you ask questions like ‘what’s a good swg %?’, we need to know your gallons, your equipment, sometimes the finish material, etc.

Go to the ‘hamburger’ menu in the upper left and select on the user icon, then profile. List everything you can on the page. To see anybody else’s as an example, turn the phone sideways if you are on mobile and it comes up under their post for easy reference. (Mine doesn’t have details, still waiting to build).
 

Liz315

Bronze Supporter
Jul 12, 2020
222
NJ
Pool Size
15000
Surface
Plaster
Chlorine
Salt Water Generator
SWG Type
Pentair Intellichlor IC-40
I’d set your FC to 5-7 with 5 being your absolute lowest. You are gonna need to manually add chlorine to the pool to bring it up that high to start. A salt system only is meant to maintain and replace what you loose each day. Your salt system at a ichlor20 is undersized you would be better with a ichlor40 because you want it double the gallons of your pool. With your current salt system your gonna have to run at 100% with your pump running for a long time plus most likely still supplement with liquid chlorine to keep it up possibly each day but definitely prior to a party.
Are you sure your TA is 280 that’s extremely high, check PH also and what your salt system salt requirements are 3,000 might not be enough.
 
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chiefwej

LifeTime Supporter
TFP Guide
Jun 12, 2011
3,721
Tucson
You have a 20k rated SWG and a 20k pool. SWG manufacturers generally rate the output based on it running 24/7 set at 100%. That is the reason we recommend a unit that is rated 2 to 3 times the volume of the pool. Salt generators are ok at maintaining the chlorine level, but for raising it quickly you should use liquid chlorine (also labeled as “liquid shock”. I have a 60k rated SWG and this time of year it’s running set at 60%, 8-10 hrs a day.
 

Newdude

Gold Supporter
TFP Guide
Jun 16, 2019
10,371
NY
+1 on the TA. We get a lot of high results at first. Those test bottles pick up some kinda static charge that affects the drop sizes in shipping. Squeeze ever so gently so that gravity makes the drop, with the bottle perfectly upside down, and wipe the tile between drops. After several tests you don’t have to wipe anymore. Try it again taking care to do it slowly and thoroughly. :)
 

jenjy

New member
Jul 15, 2021
4
Southern Oregon
You have a 20k rated SWG and a 20k pool. SWG manufacturers generally rate the output based on it running 24/7 set at 100%. That is the reason we recommend a unit that is rated 2 to 3 times the volume of the pool. Salt generators are ok at maintaining the chlorine level, but for raising it quickly you should use liquid chlorine (also labeled as “liquid shock”. I have a 60k rated SWG and this time of year it’s running set at 60%, 8-10 hrs a day.
Yes. I watched a TFP video and learned that this week. What should I do at this point? Bring the chlorine level up, run the SWG at 100% and expect the unit to burn out quicker than a unit twice the size?
 

jenjy

New member
Jul 15, 2021
4
Southern Oregon
You have a 20k rated SWG and a 20k pool. SWG manufacturers generally rate the output based on it running 24/7 set at 100%. That is the reason we recommend a unit that is rated 2 to 3 times the volume of the pool. Salt generators are ok at maintaining the chlorine level, but for raising it quickly you should use liquid chlorine (also labeled as “liquid shock”. I have a 60k rated SWG and this time of year it’s running set at 60%, 8-10 hrs a day.
Yes. I watched a TFP video and learned that this week. What should I do at this point? Bring the chlorine level up, run the SWG at 100% and expect the unit to burn out quicker than a unit twice the size?
+1 on the TA. We get a lot of high results at first. Those test bottles pick up some kinda static charge that affects the drop sizes in shipping. Squeeze ever so gently so that gravity makes the drop, with the bottle perfectly upside down, and wipe the tile between drops. After several tests you don’t have to wipe anymore. Try it again taking care to do it slowly and thoroughly. :)
Good to know! I hope that is the reason for the elevated TA. Thanks.
 

Newdude

Gold Supporter
TFP Guide
Jun 16, 2019
10,371
NY
Bring the chlorine level up
Yes
run the SWG at 100%
Also yes
expect the unit to burn out quicker than a unit twice the size
not so fast……. In Oregon you’ll have WAY less UV demand than the hot climates. It will do much better for you than it would for most.
Your season is also several months shorter so you have that going for you as well.
 

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Liz315

Bronze Supporter
Jul 12, 2020
222
NJ
Pool Size
15000
Surface
Plaster
Chlorine
Salt Water Generator
SWG Type
Pentair Intellichlor IC-40
Yes, not sure about the burn out being a major concern it won’t be crazy quick, but when it does go just get a much bigger unit. Check TA, PH and what ppm your salt system needs to be at because if it’s too low the system won’t generate any chlorine.
 
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