Low to almost zero free chlorine

[kmandeville]

Hi,

I haven't been rigorously testing my water for a couple weeks. The pool water seemed clear so I didn't worry. Today, we noticed patches of greenish algae forming in a new spots on the floor of the above ground pool. So we vacuumed it up (last vacuumed just 5 days ago and those patches didn't exist. I also noticed it seems like there's just more "stuff" floating in the water, not on the surface. I have the Intex skimmer hooked up which requires you to put a restricter valve on the other outflow valve, so the surface is getting cleaned but below the surface, not as much)

I have the intex 12 or 14" sand filter but I lowered it a week ago to running only 5-6 hours instead of the 8-10 I was running the small cartridge filter that came with the pool.

I use stabilized chlorine tablets in a floater and right now there are 3 tabs in there (1 still large, the others have dissolved a good amount already). Here are my test results from today:

Free chlorine: very low to non existent (water never seemed to turn pink)
Combined Chlorine: about 1 ppm
pH: <= 7.0
CYA: 40+ish (hard to tell how much the black dot should disappear)

So my question(s) is/are, what should I do now? Clearly the chlorine tablets aren't working like they should be. Should I switch to liquid chlorine? And if so how much and how do I apply it in an above ground Intex style pool?

Should I shock the pool? I have granulated shock.

I already plan to start running the filter longer again, clearly 5 hours isn't enough

Thoughts?

 

[CrystalRiver]

To deal with the algae you have, you can either SLAM or drain, scrub, and refill. Read the articles on SLAMming and on how to handle small/seasonal pools.

Edit, I couldn't see your signature before and assumed small because you said Intex. You need to SLAM.

 

[kmandeville]

So I can't just increase the chlorine level or how I'm adding chlorine? Have to do the SLAM? Sounded complicated. I'll look it up

 

[JJ_Tex]

SLAM is basically elevating your chlorine level and keeping it there for several days or even weeks so it can kill everything.

One common misconception that many people have is that their filter will remove and prevent algae. The filter removes Dead Algae, but it is the chlorine that does the heavy lifting here in killing and sanitizing, so chlorine should be your main focus.

 

[kmandeville]

Thanks. Will give this a try. I turned off my pool filter timer so it will run continuously. I bought a couple gallons of liquid chlorine. I still had 2 bags of granulated shock so I started with those, just put those in now to hopefully raise my level up to about 20 (based on chart with CYA around 40) and will check it later tonight, then tomorrow morning and plan to add more as needed. Wish me luck.

 

[tim5055]

So I can't just increase the chlorine level or how I'm adding chlorine? Have to do the SLAM? Sounded complicated. I'll look it up

Here are the articles you need=

SLAM - Shock Level and Maintain

We’ve all had to deal with a green pool. Clear algae from your pool with a SLAM! Read here to use shock level and maintain to clear your pool.

www.troublefreepool.com

Perform the Overnight FC Loss Test (OCLT)

The Overnight Chlorine Loss Test tells if the SLAM is finished or if you need to start a SLAM. This article says how to do the OCLT.

www.troublefreepool.com

Please stop using solid forms of chlorine, all that is doing is raising your CYA. For the SLAM you want liquid.

SLAM - Shock Level and Maintain

We’ve all had to deal with a green pool. Clear algae from your pool with a SLAM! Read here to use shock level and maintain to clear your pool.

www.troublefreepool.com

Perform the Overnight FC Loss Test (OCLT)

The Overnight Chlorine Loss Test tells if the SLAM is finished or if you need to start a SLAM. This article says how to do the OCLT.

www.troublefreepool.com

 

[tim5055]

Thanks. Will give this a try. I turned off my pool filter timer so it will run continuously. I bought a couple gallons of liquid chlorine. I still had 2 bags of granulated shock so I started with those, just put those in now to hopefully raise my level up to about 20 (based on chart with CYA around 40) and will check it later tonight, then tomorrow morning and plan to add more as needed. Wish me luck.

Those bags of shock are probably Dichlor and each one of them just raised your CYA by 6, so you are at 50 instead of 40 now.

 

[kmandeville]

Is this dichlor? I can't tell.

 

[mknauss]

Calcium Hypochlorite. Chlorine and Calcium. Does not add CYA ---

 

[kmandeville]

Phew. Thank you!

 

[tim5055]

Phew. Thank you!

Gotta be careful. I made an educated guess and missed. Sorry...

We try to teach people not to put anything in the water unless they know what it will do to the water.

 

[kmandeville]

I hear ya. I thought that if it had stabilizer it would have said it on the package.

Question: For a 10,000 gallon pool, how much liquid chlorine do I add to raise the FC to at least close to 20? And do I just pour it in near the water return slowly?

 

[kmandeville]

Sorry, I checked the bottle for the amount. Can't delete my last comment for some reason

 

[tim5055]

I hear ya. I thought that if it had stabilizer it would have said it on the package

The problem is that the stabilizer/CYA is part of the chemical composition of the products Trichlor (most tabs) and Dichlor (most granular "shock" products.

Lets look at their real names...

Trichlor is really "Trichloroisocyanuric acid"; notice the "cyanuric" hidden in there

Dichlor is really "Dichloroisocyanuric acid", again, notice the hidden "cyanuric" in there.

These are the things that many of the "professionals" at pool stores have no idea about or want to ignore.

 

[poolnoobgrandma]

Is this dichlor? I can't tell. View attachment 152074

I got a bunch of this when things started shutting down in March and liquid chlorine was hard to find. We have used it from time to time to supplement the SWG as the days got longer, sunnier, and hotter, and have had no ill effects. NOTE: our CH is not super high, so the calcium is not a problem for us. YMMV.