My chemicals are off

[G&SRay]

Hello,
I am a new pool owner and have been testing my water on a weekly basis. Last week my readings were
FC: 2.0
CC: 0
TA: 90
pH: 8.0
CH: 200
CYA: 55
Temp: 60F

To bring down the pH I added muriatic acid, I believe the pool math calculator said somewhere around 36 oz. I also added one puck of trichlor the clorox brand that doesn't have the "blue" in it.

Today my readings were
FC: 1.8
CC: 0
pH: 8.0
TA: 90
CH: 190-200 it was slightly blue at 19 drops and had a nice hue at 20 drops.
CYA: 60
Temp: 57F

Today the pool math calculator is telling me to add more muriatic acid, 35 oz, and to add baking soda.
So why am I supposed to add acid and baking soda? I would be adding an acid and a base which would put me somewhere around square one right? This just doesn't make sense to me.
I will also be adding another puck of the clorox trichlor to try and bump up the chlorine.
And of course I will be addressing the calcium hardness.
This pool was completed and filled mid December of 2017. I use the Taylor FAS-DPD test kit. The filter is a Jandy running at 150 gal/min, the pump is a Jandy flo pro with a HP of 75. We run the filter 6 hours a day during daylight hours. We are located in the Sacramento Ca area. Pool is in ground with a plaster/peppble finish, size is 21,500.

Thank you for any direction given.

 

[triptyx]

To start, you can save reagent for the FAS/DPD by using a 10mL water sample and dividing the drops by 2 to get your FC levels.

I'm assuming by the tablet adds that you don't have a SWG (saltwater chlorine generator). If you don't, you should stop using trichlor pucks and use bleach or liquid chlorine - your CYA is already at the high end of what we'd recommend and every tablet you use is making that number go higher.

What is your target TA? I'd assume it's higher than 90 if Pool Math is asking you to add baking soda. There's nothing wrong with a TA of 90, setting your target to 90 will remove the suggestion to add baking soda.

 

[Texas Splash]

Something else to consider .... I think your CH numbers might be a bit off. If I multiply 19 drop x 25 I get 475. So your CH is probably a bit higher than you think which effects your CSI position. Are you using a speedstir?

I would have no reservations with the acid bring the pH down to about 7.4-7.5, and if the TA drops a little that is fine as well. Your TA has room to go lower which might help the pH stay more stable. Of course that new plaster is still curing, so pH will always be on the rise until it fully cures.

As noted above, bump that FC ASAP, but with bleach only. Regular bleach is your pool's friend now.

 

[Jimrahbe]

Ray,

The entire TFP pool maintenance process is centered around maintaining the correct FC level in relationship to your CYA level... See this chart... [FC/CYA][/FC/CYA]

Notice in the chart that when you have a CYA of 60, you should maintain a very minimum FC level of 5 and it normally should be between 7 and 9...

The higher your CYA the higher the FC needs to be to prevent algae...

Adding more 3" tablets, just keeps increasing your CYA... That is why Trip is telling you to stop using the chlorinated tablets...

Maintaining your pH is much more important than your TA level.. as long as your pH is ok and your TA is above 50, then I would not change a thing...

Thanks for posting,

Jim R.

 

[G&SRay]

Thank you all for the advice.
Correct, I do not have a SWG so I will stop using the pucks and go grab bleach. I didn't know that a higher CYA can cause algae growth. I have a lot to learn.
My taylor pamphlet that came with the kit gives 2 ranges for TA one is 80-100 and the other is 100-120. I thought 100 would be a good safe spot.
Also the Taylor kit instructs to multiply CH drops by 10 to get CH ppm so that's where I got 190-200. At 19 drops the sample was a faint blue where 20 drops gave a slightly more vibrant blue.
About how long does it take for plaster to be fully cured? The pool has been full of water for almost two months.
Thank you for clarifying the importance of pH over TA, I thought the TA had to be corrected before pH could be balanced.

 

[Jimrahbe]

Ray,

New plaster will cause your pH to increase for up to a year... This is most obvious when the pool is new, and then steadily decreases over time...

Water features, like spa spillovers, or waterfalls, will also cause your pH to increase.

High CYA by itself will not cause algae, but as the CYA increases it makes your FC less effective, which allows algae to start growing...

Thanks,

Jim R.

 

[jseyfert3]

Something else to consider .... I think your CH numbers might be a bit off. If I multiply 19 drop x 25 I get 475. So your CH is probably a bit higher than you think which effects your CSI position. Are you using a speedstir?

You can do it with a 10 mL sample and each drop is 25 ppm or you can do it with a 25 mL sample and each drop is 10 ppm.

The Taylor instructions say to use the 25 mL sample, at the end it says "if high TA/CH is expected, use 10 mL sample and multiply drops in step 2 by 25 instead of 10." It doesn't clarify what's considered high though, which may be confusing for a new user.

 

[Meadow]

@OP...our pool was resurfaced and filled mid December last year. I insisted in conducting my own startup and glad I did. The Pool School article here is a better overview but my PB agree with NPC startup card for liability reasons. I would suggest for you to bump your FC asap using plain bleach only and leave the CH alone at 200. Based on your geographical location, your CH will climb on its own at fast rate to almost double, a year from now by means of evaporation and fill. Good luck...