KH=1

[brianw3185]

I have a 36 BF reef with just a few corals right now, but to make sure that my aquarium was ready for additions, I started to test for Mg (Salifert), Ca(Salifert), and KH (API). (NO3= <<5, PO4 = 0, RI = 1.025, pH = 8.2, these parameters have been rock steady). My initial Mg was 1150, Ca was 365, and KH was 7. Over four days, I tried to bring the Mg up by using Seachem Reef Advantage Mg, dosing first day, testing second day, dose third day, testing fourth day. The Mg went up to 1235 on day 2, and has come down to settle at 1200 without any further additions (yet). Then I added Seachem Reef Advantage Ca slowly, and have brought the Ca from 365 to 380, ok so far.
Now my KH is at 0 using the API test kit, which I have been using all along. What the heck happened to my tank?
I must note that my coralline has taken off, rocks that didn't have any for 18 mos are growing merrily, which I am grateful to see. I don't know if that has anything to do with my chemistry or not.
If the KH really is 0 or 1, why are my inhabitants still alive?
Biggest question for me is how to raise the KH if necessary, but more importantly how to get and keep the system in balance after the proper parameter range has been reached by all three Mg, Ca, KH?
Thanks for helping. PS My degree is in Chemistry, so I have half an operational aquaintance with these types of systems, you can get technical if you need to. Really appreciate the help.

 

[rkpetersen]

It's very hard to get that low. Could be test kit error. API is not great. Consider getting a Hanna checker.
If it's confirmed, could be due to uptake by coralline algae. Still seems unlikely.
Another possibility is massive abiotic calcium carbonate precipitation.
Check pumps, sump floor and walls, heaters, etc for white precipitate.
It can also precipitate in sand, making the sand hard, like limestone.
Many products available to raise alk, even just sodium bicarbonate or sodium carbonate.
If your system is really using that much alk biologically, it may be time to get a doser.
Once things are in line, a doser can keep it there without wide swings or a lot of work for you.

 

[MTBake]

No way can it be 0. It's gotta be an error. Make sure you have the correct bottles for the test and aren't using a calcium reagent bottle by mistake. Check the salinity and the calibration of whatever you use to test salinity.