Refill Chemistry check

[lyncch00]

Hi.  I could use a little reassurance with my chemistry.  I have an ozonator and use the nature2 insert.  I use dichlor once a week (one teaspoon) and mps (3 teaspoons) after each use as directed by my spa salesman.   I think it works great.   I just did a water change.   Very clean acidic well water with negligible hardness or calcium.   First I hit it with one teaspoon of dichlor.  They following day the water still had residual chlorine in it.  I added arm and hammer sodium bicarbonate to increase alkalinity.  Thats what I wanted to ask about.  The Arm and Hammers sole purpose is to raise alkalinity and ph, correct?  Now I'm using a calcium hardness increaser I got from Lowes to increase the hardness.  In retrospect I probably should have added the calcium hardness increaser before the sodium bicarbonate.    I  believe I'm going in the right direction but I wanted a little reassurance from this forum.  Thanks big time.

[sorebikr]

You'll hear from the pros shortly, but unless your tub is set into a concrete patio, you really don't need to worry about the hardness level.  And it sounds like you didn't add enough chlorine after your refill, but again, wait for the pros to weigh in.

[chem geek]

Yes, the baking soda primarily raises the Total Alkalinity (TA) and sometimes the pH depending on starting pH and how the baking soda is added.

The Calcium Hardness (CH) is only to be raised to around 120-150 ppm to help reduce foaming.  It's not needed to protect plaster surfaces since I presume your spa is acrylic/fiberglass and not plaster nor any grout in tile.

It doesn't matter which order you add these two -- baking soda and calcium hardness increaser (calcium chloride, which you can also get as Peladow or Dowflake).

[lyncch00]

thank you both.  I think Im geting the hang of this.

[Tman122]

MPS and Dichlor have a tendency to drive down PH/Alk over time as you use the tub. So you likely will have to continually drive them up. But relax and soak. Your on the right track.