Low alk on freshly mixed saltwater

[philmck]

Randy,
I mixed my first batch of Tropic Marin Pro this morning. Powerhead has been running in tub all day. Salt mixewd with RO/DI. Salinity measures at 1.026 with both refractometer and glass hydrometer. So I go test the alkalinity this afternoon: Three tests 5.7, 6.1 and 6.3 dkh with Salifert test kit.

The salt mix was prepared in the basement temp= 60ish degrees. Do you think that this is a CO2 saturation issue? Is the salifert titration temp dependant?

I don't usually test for alkalinity on fresh batches of salt mix, but with the switch to the new salt I though I would see if the extra money was worth it. Bad batch or wait a while?

thank you in advance,
Phil

 

[Randy Holmes-Farley]

CO2 has no impact on alkalinity. I don't know why this batch might read low, except the obvious of testing error or a "bad" batch. I'm not sure how high TM usually is, but that isn't all that low. Not much below NSW.
You can boost it with a little baking soda if you want:

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