What Should Fc Be Just Before Using?

[lpad]

I am wondering what FC level I should aim for the water to have right before we use it? We have an ozonater. Do you usually aim to add chlorine before use *and* after use? Or should I increase the amount of chlorine added afterwards so that I don't have to add anymore the next day just before we use it?

Secondly, I've noticed that over the course of a few weeks (3 ish) my TA is creeping up a bit. It started in the 50-60 range and now it's a solid 70 according to my Taylor kit. pH has crept up a little also (from about 7.5 to about 7.7).

I have been using the dichlor then bleach method. We stopped adding dichlor on 12/10 and switched to bleach then. All this creep has been after we switched to the bleach. Because we stopped using dichlor almost a month ago, I was planning on adding one dose of dichlor soon (per the recommendations because CYa drops each month). I'm figuring that this will drop the pH back into the 7.5-7.6 range but I don't know if it affects TA at all. Thoughts?

Oh, and we have already had to have our heater replaced on our month old D1 nautilus. We have had problems with the breaker tripping ever since we hooked the tub up. It happened with increased frequency until by Monday it tripped continually and wouldn't even turn on. Finally the problem was isolated as the heater (they say it must have leaked some moisture even though they couldn't see anything). hope this is NOT a sign of things to come. Anyways it is fixed as of now and we have been enjoying the tub for the past month.

[chem geek]

Most people using either the Dichlor-only or the Dichlor-then-bleach method add enough sanitizer after their soak so that they have a small residual before their next soak, usually at least 1 ppm FC. Some people try and maintain a higher FC level at all times, but then end up soaking with more sanitizer and usually smell it (or the disinfection by-products such as monochloramine) as a result. The latter approach is technically more sanitary, but probably not worth it as long as you make sure that 1) the FC level doesn't ever get below 1 ppm except during the time (usually an hour or less) that you soak and 2) your CYA level doesn't get too high so stays near 30 ppm.

I can understand the pH rising over time and the TA will rise with it a little, but the larger TA rise you are seeing is unexplained after you switched to bleach (assuming you didn't add any Spa Up or Alkalinity Up chemicals such as sodium carbonate or sodium bicarbonate or added any Dichlor). Perhaps you had some evaporation and refill since the fill water will add whatever is in it (typically TA and CH) to your tub. How much do you end up filling up your tub to make up for evaporation (if you do that at all)?

Adding around 5-6 ppm FC of Dichlor and then having that chlorine get used up will lower the pH by around 0.15 units (assuming you have 50 ppm Borates in the water). You could also use some additional dry acid to lower the pH and TA. At the higher TA level, the pH may rise more quickly so lowering it (and pH) with some acid will get ahead of that.