Results: alk too high?

[salinda]

I tested my water just now with a PS233. My pool needs a little balancing because I went on vacation and the ph drifted. Also, I just changed my pump and I am trying to get a handle on the pool with the new flow etc.

The ph is a little low below, but only because I added acid only 1 hour prior. Please note that I have an swg.

I also have a little confusion because I thought TC=FC+CC but I get a different reading for TC from the OTO test. Maybe something is faulty or maybe I need new dpd powder....

FC 2.5
CC .5 (could be less...was VERY slightly pink before one drop of r-0871 added)
TC (oto) 1.5
pH 7.0
Alk 75
Cal 520
Cya unknown because I don't have the Reagent refilling instructions, but last reading was 55 and we have gotten no rain to dilute it since then.
Temp 82
Salt 5190 (from pool store bought test strip)

My Alkalinity has been slowly dropping since last fall. Should I add baking soda to boost it? Does that work even in a saltwater pool? Should I wait for the ph to rise and test the alkalinity again before I do anything?

What's the deal with the discrepancy in the chlorine readings?

[waste]

Salinda, if FC + CC doesen't = TC, there is a testing problem, either the reagents are no good or you are reading the results wrong (believe me, I know how hard it can be to compare the colormetric tests at times, judging the variations between the 'given' values vs. your result). If you think that the reagent might be bad, replace it.
I suspect that the alk is dropping due to airation (do the returns point up?, do you have a 'water feature' that would make the water bubble?), as your pH is 7.0. This is consistant with the alk reduction method advocated here (low pH and some airation will result in the alk steadilly dropping). Also, how low can you test with your kit, if 7.0 is the bottom, it's very possible that the pH is actually lower than 7.0. Go ahead and add the baking soda, it'll raise your alk and also drag the pH up (yes, it's fine for SWCG pools).
I hope this helps, if you have any further questions or need clarification - don't hesitate to ask. - Waste

[salinda]

My ph kit tests down to 6.8. It is definitely NOT that. It is a little oranger than 7.0, so I am calling it that....

I will try adding the baking soda....

[aylad]

The OTO test is less accurate than the dpd/fas test for chlorine....if you're testing with the dpd/fas, use those results for FC and CC.

Janet