Alk driving me nuts.

DomC · May 4, 2014

I can't figure out why when I do a water change my alk drops. I tested my tank before water change and came back at 7.5 then I tested freshly mixed water and tested at 9.5. I wait and hour then tested DT and came back at 6.53. I can't for the life of me figure out why it drops so much. I just started dosing soda ash to help. I went with soda ash since my oh is at 7.8 to 8.0.
If anyone has any input to help me figure out why is drops and how to go about dosing.
Here's a few other parameters
Mag 1350
Calcium 460
Salinity 1.70253
Nitrite 0
Phosphate .01

Mainly have SPS

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mike007 · May 4, 2014

You need to alk. level where you want It and then quit dosing for 3 days and then retest to see what your tank Is consuming. Divide results by 3 and that will tell you your daily consumption. Then you can go to the brs reef calculator to determine how much to dose each day to keep stable. Are you sure your test results are accurate 1.70 salinity is way too high.

redfishbluefish · May 4, 2014

That salt number can't be right.....got to believe that 7 snuck in there somehow.

I'd let you calc number come down a bit. High calc will drive down alk.