Refill - Low Ch

[SJ Hart]

Well, because of this forum, I know a lot more than I used to.... Anyway, just filled my tub (580 gallons). CH is around 30 (straight from the city water supply). So, I'm raising it to around 130-150 per the recomendations on this forum. pH is OK right now, but TA is very low (I did add a bit of alk increaser) = TA is now around 40. So, I should get my CH up and then see what happens to TA/pH? Thanks. SJ

[quantumchromodynamics]

If the tub does not contain any plaster or grout, I would keep the calcium closer to 100 to help prevent scale from forming on the heater element if the heater is electric. If the heater is a gas heater with a heat exchanger, then you can keep the calcium slightly higher at about 130.

Raise the alkalinity slowly in small increments until the pH maintains stable. Once the pH stays at a good level with minimal adjustment, then your alkalinity is at the right level.

If the tub does contain any plaster or grout, it's important to balance the Calcite Saturation Index to prevent them from being dissolved.

[SJ Hart]

Thanks. Raised the CH. TA is only around 40, but pH is stable at 7.6. I'll monitor, but my TA always seems to low.... No plaster or grout (portable Jacuzzi J480 model) - so I shouldn't be concerned with CSI? SJ

[quantumchromodynamics]

Low CSI is really only relevant to calcium based products, such as plaster or grout.

High CSI is relevant to preventing scale. It is important to not let the CSI go too high.

The best level for your alkalinity is where it keeps your pH stable.

If your pH is constantly low, then your alkalinity is too low. If your pH is constantly high, then your alkalinity is too high. If your pH is staying consistent at 7.6, then your alkalinity is just right.