Please help on what to do to balance water after algae outbreak

newbie_pool

Well-known member
Oct 30, 2013
55
Houston, TX
Pool Size
18200
Surface
Plaster
Chlorine
Liquid Chlorine
Hi,

After owning the pool for several years, I thought I know it all but apparently I got things wrong. Long story short, we've been having out of control algae due to very high CYA (129) so we did as suggested by replace more than half of our pool water with fresh water and shock while doing that. Here is my current reading:
FC - 0.09
CYA - 49
TA - 143
PH - 7.9
CH - 180
Per pool calculator, it suggests I need to add muriatic acid to bring down the ph and then aerate to bring up the ph. My questions are:
1. So I added the muriatic per suggestion to bring down ph to 7.0. What's next? How long do I have to wait before proceed to next step? 4-5 hours?
2. Then once my ph level will be at 7.0, the pool calculator suggests to add borax to bring up to 7.6 which in return help to bring down the TA level. Is this what aerate means? I never fully understand what/how to aerate the pool? Is just adding the borax enough to bring up the ph level? Of course I will have the pump to run all the time while doing this. Is this enough?
3. I also need to add shock into the pool. Right now it's 0.09. When can I do that? During/after step 1 or step 2 above? Can I add now? I'm so terrified of algae that I'm afraid if I don't have enough chlorine, the algae will grow back.
4. When can I increase the CH level? After all the steps?

Is this enough to help killing the algae? Do I also need some algae killing chemical on top of these? Sorry for the long post but I feel so defeated with my pool at this moment.
 
Last edited:

IceShadow

Gold Supporter
TFP Guide
Jun 8, 2019
3,717
Milwaukee, WI
Pool Size
20000
Surface
Vinyl
Chlorine
Liquid Chlorine
First and foremost, how are you testing? The values you give aren't something that comes from a dropper kit, so I'm suspecting they're from a pool store - that may or may not be accurate. So our first recommendation will be to get your own test kit, either a Taylor K2006c or a TFT-100. Answering what I can:

1) 30 minutes with the pump on is typically enough to let muriatic acid mix thoroughly in a pool.

2) Don't add borax, as that will raise your pH and slightly raise your TA. You may not need to worry about your TA - it will go down with additions of muriatic acid, which you'll be adding to lower your pH as it raises over time.

3) Advice on this will depend on your chem levels which is hard to trust when they're from a questionable source. I would advise adding enough liquid chlorine to add 5ppm of FC daily, order a good test kit, and when the kit arrives, run a full battery of tests for us to help from. :) The only chemical you need to kill algae is chlorine, but without reliable test numbers, you'll be flying blind on how much to add.
 

newbie_pool

Well-known member
Oct 30, 2013
55
Houston, TX
Pool Size
18200
Surface
Plaster
Chlorine
Liquid Chlorine
First and foremost, how are you testing? The values you give aren't something that comes from a dropper kit, so I'm suspecting they're from a pool store - that may or may not be accurate. So our first recommendation will be to get your own test kit, either a Taylor K2006c or a TFT-100. Answering what I can:

1) 30 minutes with the pump on is typically enough to let muriatic acid mix thoroughly in a pool.

2) Don't add borax, as that will raise your pH and slightly raise your TA. You may not need to worry about your TA - it will go down with additions of muriatic acid, which you'll be adding to lower your pH as it raises over time.

3) Advice on this will depend on your chem levels which is hard to trust when they're from a questionable source. I would advise adding enough liquid chlorine to add 5ppm of FC daily, order a good test kit, and when the kit arrives, run a full battery of tests for us to help from. :) The only chemical you need to kill algae is chlorine, but without reliable test numbers, you'll be flying blind on how much to add.
Thanks for quick response. So I do have K2006c kit here at home and the values above are indeed from the pool store. I didn't think they are not as accurate. Let me test using my Taylor kit and will update with the new values. I know my FC level is low, can I shock now?
 

newbie_pool

Well-known member
Oct 30, 2013
55
Houston, TX
Pool Size
18200
Surface
Plaster
Chlorine
Liquid Chlorine
Here is new values using Taylor kit:
FC - 0
CYA - 55
TA - 120
PH - 7.0

So my PH is now at 7.0 since I added the muriatic acid. What is next? Should I follow the SLAM process to shock now? Do I need to raise PH?
 

ajw22

Gold Supporter
TFP Guide
Jul 21, 2013
35,275
Northern NJ
Pool Size
35000
Surface
Plaster
Chlorine
Salt Water Generator
SWG Type
Pentair Intellichlor IC-60
Your CYA is 60. You cannot guess at values in between the lines since the scale is logarithmic, not linear. If the dot disappears between 60 and 50 we round up and call it 60.

Your SLAM FC will be 24.

You do not need to raise your pH.

Follow the SLAM Process
 

IceShadow

Gold Supporter
TFP Guide
Jun 8, 2019
3,717
Milwaukee, WI
Pool Size
20000
Surface
Vinyl
Chlorine
Liquid Chlorine
What he said. Your pH will naturally rise with your TA at 120. You're good to proceed straight to SLAM. Test as often as you can, at least 3 times a day (before work, after work, before bed) and if you can, once every couple of hours, bring the FC back to the SLAM level, and keep it going until you're crystal clear, have no overnight loss, and no signs of algae. :)
 

newbie_pool

Well-known member
Oct 30, 2013
55
Houston, TX
Pool Size
18200
Surface
Plaster
Chlorine
Liquid Chlorine
Your CYA is 60. You cannot guess at values in between the lines since the scale is logarithmic, not linear. If the dot disappears between 60 and 50 we round up and call it 60.

Your SLAM FC will be 24.

You do not need to raise your pH.

Follow the SLAM Process
Thanks, so I guess I can ignore this?
  • Check and adjust the PH to between 7.2 and 7.5. The PH test isn’t reliable during SLAMing so make sure to take care of this before you start.
 

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newbie_pool

Well-known member
Oct 30, 2013
55
Houston, TX
Pool Size
18200
Surface
Plaster
Chlorine
Liquid Chlorine
Thanks all as this is truly helpful. I know you guys told me to not too trustful with the pool store. However, I just spent $$ on buying the shocks from Leslie (being pressure at that time). Can I use those bags? Would that raise my CYA than it should?

Or to be safe, stick with liquid chlorine? My previous issue was over use the Clorox tablets which caused the CYA built up over years.
 

ajw22

Gold Supporter
TFP Guide
Jul 21, 2013
35,275
Northern NJ
Pool Size
35000
Surface
Plaster
Chlorine
Salt Water Generator
SWG Type
Pentair Intellichlor IC-60
Liquid chlorine is the thing to use during the SLAM Process. You can manage your FC levels more precisely.

I suspect using those Clorox tablets also added copper to your pool. Did your pool store test for metals and copper?
 

IceShadow

Gold Supporter
TFP Guide
Jun 8, 2019
3,717
Milwaukee, WI
Pool Size
20000
Surface
Vinyl
Chlorine
Liquid Chlorine
Calcium Hypchlorate - Cal Hypo. They will add calcium. What's the calcium level of your fill water? I'm always hesitant to tell anyone in Texas they can do anything that adds more calcium >.>