Chlorine tablets aren't maintaining chlorine levels

[ImNotAChemist]

Hello! I'm fairly new to pool ownership. Lots of my frantic Google searching brings me to TFP so I figured it's about time to join.
We bought a home with an Inground 10,000 gallon pool with sand filter last August. We only used it a few weeks before closing it for the season. We inherited the pool with basically no experience and all of the chemicals were off. We finally got it swimmable and had relatively no issues after the initial dropping $300 worth of chemicals in it.
This season, however, our chlorine levels will not stay up no matter what we do. We're using the same 3 inch pucks from last season. Our chlorine levels have been hovering between .2 and .4 despite using 3 pucks in the floater (overkill for our pool size) and shocking the pool at least 4 or 5 times now since the initial opening. It looks great. The water is crystal clear. We've played around with the cya and phosphates to see if those are the reason for the low chlorine, but we just got both of those in spec and it hasn't solved our chlorine issue. We also have a solar cover.

Can someone give me guidance on this? I've seen a lot of people here use liquid chlorine which I'm not opposed to, but we spent a fortune on the Leslie's tabs last season and I would like to use them if possible.

Stats:
Ph - 7.1. (this *just* dropped due to rain so I'll be treating that)
Alk- 106
Cya- 45
Fac - .48
Tac- .6
Ch-236
Tds- 500
Pho-0
Fe-0
Cu- .1

 

[Texas Splash]

Hello and welcome to TFP! My initial thoughts are you in the early stages of an algae bloom. Understand that tablets/pucks contain stabilizer, so as each one dissolves, that CYA level increase to the point that free chlorine (FC) cannot keep up. See our FC/CYA Levels. Tabs are also acidic which is why your pH level is low. In addition, even what appears to be clear water can have algae, so the FC drops very fast. You also are using a pool store for testing, chemicals, and probably some advise, all of which is not only very expensive but often times misguided. So here's what I would recommend:

1. Remove those tabs ASAP. Using our PoolMath APP, determine how much chlorine would be required to increase the FC to about 7-8 ppm. It's perfectly safe for now.
2. Get a proper test kit and test your own water. That's key. I recommend the TF-100 (link in my signature), but the Taylor K-2006C will also work.
3. After today and before you receive your own test kit, add about 1/4 gallon of liquid choline to the water each day.

Once you receive your test kit, post a full set of test results and you'll see how all of this comes together. It's very easy once you get past the initial learning curve. If you have questions, just ask. Lots of people here to assist.

 

[Oly]

Welcome to TFP, this place is a goldmine for pool and spa owners. Invest in a proper test kit for your pool it really is the foundation for proper water chemistry balance.

 

[cowboycasey]

Welcome to TFP

Save the 3 inch tabs for vacations and when you need to raise CYA... Grab a great test kit and you will be on your way to a trouble free pool

 

[ImNotAChemist]

Interesting development... I took a sample to a different pool store and now my chlorine is 7! I imagine it didn't need such aggressive shocking after all. I will be buying my own test kit! Thank you for the advice

 

[cowboycasey]

and if you go to another store it will also be different, that is how they make money of you by selling every potion under the sun except what you really need

 

[ImNotAChemist]

I literally can't wrap my head around how the chlorine can be basically non existent on one test and super high on another! Now we can't swim today I'm hella annoyed. Definitely ordering my own test kit and ditching the stores. I also did no adjustments to my ph and really don't think it's possible it went from 7.1 to 7.6 overnight, which is what the second store reported.

So I have been holding off on running my heater because of the ph, but now I guess I shouldn't use it because of the chlorine levels too? I'm not going to do anything else chemical wise until I've got my own kit.

 

[mknauss]

Now we can't swim today I'm hella annoyed.

So if you believe the FC of 7, then I suspect you believe the CYA of 45 from your first test? If so, 7 ppm FC is in the range the FC needs to be. You can swim in water with a CYA of 45 (we call that 50) up to 20 ppm FC. You will never know the difference if the water is properly managed.

 

[cowboycasey]

You can swim in you pool no issue.. if you can see the bottom and there is chlorine in it..

Your CYA is probably about 50 (I am guessing) and at 50 you can swim with your chlorine up to 20 PPM

 

[ImNotAChemist]

Oh wow I did not know that... The chlorine won't burn eyes that high? Sorry, I am a total newbie. I've been reading some here but obviously not enough we just added the cya so I know those levels should be decent but apparently someone's test is off.

 

[Texas Splash]

Your list will look this as well once you learn to test your own water. One of the few things we as home owners can still do on our own.

 

[Rich807]

Your sanity & your wallet will thank you once you switch away from the pool store merry go round.

 

[Selenap]

I maintain 5-7 ppm chlorine in my pool. Nary a problem swimming in it. I can’t smell it or pretty much tell it’s in there without testing. I’ve overindulged and brought it up to 9-10ppm and never noticed it.