Need to SLAM after fresh water top up every time

[Kimden]

After every fresh water top up this year I’ve had to SLAM. Made sure chlorine was adequate after adding fresh water, was 8.5 ppm last night after fresh water add in afternoon. Opened pool at 11 am 4.5 ppm chlorine, water not as crystal clear as usual. Skimmer socks also had algae in them. This is the 3rd top up so far this year and 3rd slam. What is going on? Water is house water, not well, the stuff we drink. HELP!

 

[Cwiggs]

Welcome to TFP!

What test kit are you using? You should update your signature with your pool info so we can help.

 

[Kimden]

Taylor k2006
81000 litres
Vinyl
Added it to my signature

 

[Kimden]

Welcome to TFP!

What test kit are you using? You should update your signature with your pool info so we can help.

Taylor k2006
81000 litres inground
Vinyl

 

[Cwiggs]

Can you post a full set of tests? FC,TA,CYA,pH, etc?

 

[Kimden]

Can you post a full set of tests? FC,TA,CYA,pH, etc?

Before adding fill water

fc 8.5
Ta 110
Cya 50
Ph 7.4

after adding water and testing 2 hours later
Fc 6.5
Ta 110
Cya 50
Ph 7.4

Added 1.5 litres of bleach which adds 2ppm, so Fc 8.5 before bed

NOON next day
Fc 4.5
Ta 110
Cya 50
Ph 7.4

 

[Kimden]

This is the 3rd time I’ve topped up this year, and I’ve had to slam after each time.

 

[Cwiggs]

The tests look mostly fine. FC of 4.5 around noon scares me, unless you put bleach in right then. If your FC is 4.5ppm around noon it'll probably be below 4ppm by the time the sun goes down. With a CYA of 50 you should target 6-8 and never get below 4ppm. I would really target something higher than 6-8 so you don't risk getting near 4, like you did recently.

Tell us more about your SLAM though, how long did it last, do you have pictures of the pool through the process? Did you make sure to pass the OCLT before ending the SLAM?

Also do you have anything in your pool that could hide algae, like ladders?

 

[newdude]

seriously though. You are most likely dangerously low when you fill, which tips the cloudy scales. If you run hot to start with, you have lots of safety net FC to spare.

 

[Kimden]

View attachment 350166
seriously though. You are most likely dangerously low when you fill, which tips the cloudy scales. If you run hot to start with, you have lots of safety net FC to spare.

I had 8.5 ppm of chlorine when I started to top up

 

[Kimden]

The tests look mostly fine. FC of 4.5 around noon scares me, unless you put bleach in right then. If your FC is 4.5ppm around noon it'll probably be below 4ppm by the time the sun goes down. With a CYA of 50 you should target 6-8 and never get below 4ppm. I would really target something higher than 6-8 so you don't risk getting near 4, like you did recently.

Tell us more about your SLAM though, how long did it last, do you have pictures of the pool through the process? Did you make sure to pass the OCLT before ending the SLAM?

Also do you have anything in your pool that could hide algae, like ladders?

As soon as I tested 4.5 ppm, I added 3.5l litres of bleach which is just shy of adding 5 ppm. So that would take it up to 9ish. At that point I said eff this and started my slam right away. But I’ve had to do this every time with topping up water. My chlorine was 8.5 when I started adding the water.

My question is why is my fresh water eating my chlorine? Do I need to bring to slam levels before I add my inch of fresh water?

The tests look mostly fine. FC of 4.5 around noon scares me, unless you put bleach in right then. If your FC is 4.5ppm around noon it'll probably be below 4ppm by the time the sun goes down. With a CYA of 50 you should target 6-8 and never get below 4ppm. I would really target something higher than 6-8 so you don't risk getting near 4, like you did recently.

Tell us more about your SLAM though, how long did it last, do you have pictures of the pool through the process? Did you make sure to pass the OCLT before ending the SLAM?

Also do you have anything in your pool that could hide algae, like ladders?

I added 5ppm chlorine as soon as I saw it was at 4.5 fc.

I’m wonder why my fresh water is eating my chlorine every time I add it? Should I bring to slam level before adding fresh water from now on? It’s really frustrating because otherwise pool has been impeccable.

no ladders or anything to hide algae. It’s only because of this freshwater top up.

 

[newdude]

So fresh water / rain can usually only affect you by the appropriate percentage. One inch of either will only drop the average depth pool by 2% or so. Unnoticeable for most providing they mix and the untreated water doesn’t sit on top getting stagnant.

You appear to have an issue and anytime you think there may be an issue, an Overnight Chlorine Loss Test is needed to rule out algae.

 

[Cwiggs]

The next time you are ready to fill I would do an OCLT before you fill to verify there is no algae in your pool before you fill. If there is no algae and your FC is above target, and never falls below the min then I'd assume you have an issue with your fill water. If you fill water has algae, that's a more concerning problem I think.

 

[newdude]

If you fill water has algae, that's a more concerning problem I think

This one has been bothering me all afternoon as I went about my day. It’s not impossible to have issues with drinking water, but to be so bad it can chew through 20k gallons of treated water, and highly treated at that (8.5 ppm) ?

I would not even be showering in it until this is proven one way or the other. @Kimden, I can’t believe I’m actually wishing algae on a fellow member, but I really think you’d be better off if it’s the pool. Plus we can help fix that

 

[Kimden]

As soon as I tested 4.5 ppm, I added 3.5l litres of bleach which is just shy of adding 5 ppm. So that would take it up to 9ish. At that point I said eff this and started my slam right away. But I’ve had to do this every time with topping up water. My chlorine was 8.5 when I started adding the water.

My question is why is my fresh water eating my chlorine? Do I need to bring to slam levels before I add my inch of fresh water?

I added 5ppm chlorine as soon as I saw it was at 4.5 fc.

I’m wonder why my fresh water is eating my chlorine every time I add it? Should I bring to slam level before adding fresh water from now on? It’s really frustrating because otherwise pool has been impeccable.

no ladders or anything to hide algae. It’s only because of this freshwater top up.

Oops double replied

The next time you are ready to fill I would do an OCLT before you fill to verify there is no algae in your pool before you fill. If there is no algae and your FC is above target, and never falls below the min then I'd assume you have an issue with your fill water. If you fill water has algae, that's a more concerning problem I think.

I was at 8.5 ppm June 24th at 6pm
7.5 ppm June 25 at 1 pm
right there is an OCLT that passed

I’m totally stumped, my water is city drinking water. Could I have a hose problem? Algae in my garden hose?

The next time you are ready to fill I would do an OCLT before you fill to verify there is no algae in your pool before you fill. If there is no algae and your FC is above target, and never falls below the min then I'd assume you have an issue with your fill water. If you fill water has algae, that's a more concerning problem I think.

 

[newdude]

Could I have a hose problem? Algae in my garden hose

It would have to be BAD. It's totally possible though. Fill it with a gallon of bleach and tape/Cap the ends. Swish it around real good and let it sit for a while. Swish it a few more times before rinsing

 

[AK-]

I’m totally stumped, my water is city drinking water. Could I have a hose problem? Algae in my garden hose?

Is your garden hose transparent or translucent?
Algae does not grow without sun.

I like experiments… so I’d fill a clean large bucket with 42 liters of water from you hose and add 1ml of 7.5% Bleach (that will be 2ppm FC). Keep the bucket protected from the sun and heat. Test the FC about 2 hours later. If you lost FC than you fill water is the issue.

 

[AK-]

Do you now how your water is treated?

Ammonia seems to have some use in water treatment in some places and it is known to “devour” chlorine.

 

[jseyfert3]

Have you tested your tap water for FC/CC?

 

[Kimden]

Do you now how your water is treated?

Ammonia seems to have some use in water treatment in some places and it is known to “devour” chlorine.

Looks like there is ammonia added. I never had this problem last year, that’s why I stumped. It’s a new thing this season.