How to figure out theoretical CYA level from tablets

[rj2222]

Hi everybody. Hope there's some math and chem wizards out there who can help. I have a 16'x48" AGP, but this year it seems like i can't get the chlorine to stay in the pool, so my buddy gave me two HTH 3" tablets that have CYA in it (the container he took them out of had an orange lid).

I know the container says that size tablet is for 10,000 gallons, and i think mine is between 5-6k gallons. So i'm wondering in theory, how many of those 3" tablets would get me to the right CYA levels before i can switch back to the non-CYA ones.

I know there's a lot of factors that affect CYA, but i'm just wondering in theory here. He only gave me two tablets because neither of us were sure how to proceed, but we figured those would at least put some CYA in the pool to help. Wanted to put the first one in tonight, but wanted to get some help here first before i drop it in.

 

[jblizzle]

Use the Effects of Adding Chlorine section of PoolMath to calculate what each 8oz (likely) tablet of trichlor will add to your pool.

How many you can use depends on what your current CYA level is.

If you can not keep chlorine in the pool, then you likely need to follow the ShockLevelAndMAINTAIN Process

 

[chem geek]

There is also the general rule that for every 10 ppm Free Chlorine (FC) added by Trichlor, it also increases Cyanuric Acid (CYA) by 6 ppm. This rule is independent of pool size or Trichlor concentration.

 

[rj2222]

I guess I should have said "can't keep chlorine in the pool as well as it should be due to the lack of cya". All my other levels are acceptable so far, and obviously I have no CYA in it yet.

I know the tablets container say they are for 10,000 gallons and should last a week for the chlorine part, so with my size pool I know the tablets are almost twice the size of what I need, but I'm not going to roll with these all summer since I only have two haha. Not sure how that changes the general rule for me.

Off to try the PoolMath calculator!

 

[rj2222]

I'm not doing very well at this PoolMath calculator. I went to the bottom and figured out my pool is 6,000 gallons, so then I went back to the top to put that in the gallons thing. I then did my Suggested Goal Levels back at the bottom, then went back up to the top to Calculate. But nothing appears to change.

Maybe I'm better off nailing down the general rule for my size pool haha

 

[jblizzle]

You have to input your NOW numbers from your testing and the TARGET numbers to what level you want. The goals just provide suggestions.

 

[rj2222]

Totally makes sense now. I was wondering why it said now and target for what I thought was referencing the gallons right below it haha

- - - Updated - - -

OK, so according to this for the CYA,

Add 32oz by weight or 33oz by volume of stabilizer or add 83oz of liquid stabilizer.

and according to the Affects of Adding Chlorine part, it says 32oz of trichlor will raise CYA by 22.

So if i'm following along right, now I need to figure out how many ounces each one of those 3" tablets contains, then divide that into 32 to see how many of those tablets I can use?

 

[jblizzle]

Most are around 8oz. Don't add stabilizer and use Trichlor unless you account for the CYA from both.

 

[PAGirl]

I believe the thing you want to experiment with is further down the page...... The last section.

 

[anonapersona]

Use Pool Math and find what 16 oz of trichlor (2 tablets) gives you for CYA.