Wacky parameters, please help!

[ACBlinky]

I have NO idea what's going on in our tank, I'm hoping someone can give me some chemistry help.
Our current parameters are:

SG 1.025 (refractometer)
NH3/NO2/NO3 0
PO4 0.8 (Hanna checker)
KH 12.9 (Hanna checker)
Ca 593 (Hanna checker, did test twice)
Mg 1400 (Red Sea titration test)

I have noticed some of the corals looking less than completely happy, which is why I did the tests today.

I did a 20% water change a week ago, with Reef Crystals salt. I knew that Ca and alk were running high, so I haven't dosed ANYTHING and now... the numbers are higher. How is this possible?

I know that alk, Ca and Mg work together; I figured if Ca and alk were too high, Mg would be low, but it's fine. So... what can I do to bring things back to normal?

 

[Toddrtrex]

Test your water change water -- before you put it in the tank -- and see what numbers you have, the salt could be the issue.

As for the phosphates, are you using RO/DI water?

 

[ACBlinky]

Phosphates are my fault, I'm spot feeding dendros, duncans, a big sun coral colony, along with photosynthetic LPS corals that are slightly bleached (due, I'm assuming, to the whacked out parameters), and I absolutely overfeed frozen foods. There's very little algae in the display -- only film algae on some rocks and the back wall; the chaeto and caulerpa in the sump grow like stink, but I guess they can't keep up with it. The PO4 doesn't seem to be hurting anything, in that our one established SPS coral is growing well, there's very little microalgae (I actually spot feed the turbo snails and urchin or they'd starve). FWIW I am using tap water, but our tap water has very nice parameters. I haven't tested it for a bit, but usually the PO4 is negligible, NO3 is near zero.

RC salt lists its parameters on the side, basically ideal Ca, alk and Mg at 1.026 and our SG is lower than that, but I can absolutely mix some up and test to see what I get.

I guess what I'm asking is a) how on earth are all three of these parameters (alk, Ca and Mg) ALL that high, without precipitating out, and how do I get them back where they should be without shocking anything?

 

[rbp 4 135]

I was using RC for awhile my self and was getting perameters not to far off of what you are seeing, @ 1.026 per refractometer and hygrometer (both calibrated). I have since switched back to Red Sea salt.

 

[shovelrider]

Test the new salt mix and compare the numbers on the side of the bucket. Sometimes batches are off...