Sanitizer and Oxidizing Shock

[Action]

Went to the pool store and my FC, TA, CA was 0 with high phosphates. I had people try the pool yesterday and they said the bottom was a little slippery/mushy so obviously algae was starting... just a few days ago my chlorine levels were fine. I have tabs but those are SLOW.

Anyways, with 25k gallon pool, I was sold the Sanitizer (Dichloro) and Oxidizing Shock (Potassium Peroxymonosulfate) to raise my chlorine levels.

I did some research and saw these are both shocks that serve the same purpose? I was told to scrub then add 3 lbs of the Sanitizer, then an hour later add 3 lbs of the Oxidizing Shock.

Is this correct?

 

[chem geek]

Welcome to TFP!

By CA do you mean Calcium Hardness (CH) or Cyanuric Acid (CYA)? If the CYA is truly zero, then shocking with Dichlor would be a way of adding both chlorine and CYA at the same time. However, the oxidizer is a waste of money. After you use some Dichlor (enough for around 30 ppm Free Chlorine or so, IF your CYA level is truly zero), then you would use chlorinating liquid or 6% bleach. You do not want to use too much Dichlor or Trichlor (stabilized chlorine products) or else your CYA level will get too high.

One problem is that pool store testing is notoriously poor, especially for the CYA level. So you might be better off just getting chlorinating liquid or bleach and adding it to the pool until you get a sustained Free Chlorine (FC) reading. Once you know the pool's true CYA level, you can increase it if necessary. You should get yourself a proper test kit (the TFTestkits TF-100 or the Taylor K-2006). Read the Pool School to learn more about how to properly maintain your pool.

 

[jblizzle]

Did they give you a pH number? If TA is truly zero, then your pH is in the 4.5 range ... very very low. Or as was just stated, the testing could just be really inaccurate.

Posted from my Droid with Tapatalk ... sorry if my response is short

 

[UnderWaterVanya]

My story includes a pool test (several actually) at a local store which said my pH was 7.5 but my TA was 0. I blindly (no test kit then) added a boatload of alkalinity increased (psst - baking soda in a costly container). And when I could finally test on my own my TA was 180! The store was still showing me a test w/20ppm TA!

Morale - don't trust pool tests you don't do yourself!