Strange Starting Parameters on New Tank?

[Chris918]

Hey guys.

If this would be better answered in the "New to the hobby" section please let me know and I will move it. This is about the chemistry of my tank however.
Currently the tank is empty. The tank has been set up for several months. I am at the point where I believe it is fully cycled and the rock fully cured. I plan to have this be my first tank with corals and I have my two part from BRS ready for dosing, but I am getting some unexpected pre-dose results from my Red Sea kit.

Results:
Ca: 485 ppm
Alkalinity: 13.4 dKH
Mg: 1240 ppm

Further tests: (API)
Ammonia/Ammonium: 0 ppm
Nitrite: 0 ppm
Nitrate: 5-10 ppm
pH: 7.9

Specific Gravity: 1.025
Temperature: Constant 78 degrees.

I use Instant Ocean salt mix (not reef crystals),
This tank's water was set up with an RO system with a newly installed DI Resin, but I wasn't getting down to 0 TDS. It was closer to 5-7, which I also saw as strange. I let it run for 2 hours to get this reading and the system was less than a month old, but I admit it was cheap. I have since replaced it with BRS 150 GPD 6 stage RO/DI and I get 0 TDS on that every time and love it.
The tank was started with live sand, pukani rock, and some additional dry rock from a LFS.

So what do you guys recommend? Does this seem strange to you? I thought such a high alkalinity would mean a high pH. I have also never dosed the tank so unless the salt mix has all these elements in it I am at a loss for that and such high readings.

Should I do a total water change with the brand new 0 TDS RO/DI water, wait a week and then test again?

I greatly appreciate your guys' time in reading this and I look forward to any advice you have for me.

Thanks!

Chris

 

[vhuang168]

I would calibrate the refractometer to make sure you are actually at 1.025. A higher SG will account for the higher levels of alk n ca.


Sent from my iPhone using Tapatalk

 

[Chris918]

The refractometer is only 2 months old. Would it really need to be calibrated already? Seems so soon. Still I'm not crazy for thinking these levels are abnormal it seems lol

 

[vhuang168]

You should have calibrated before you even used it the 1st time.


Sent from my iPhone using Tapatalk

 

[Chris918]

I certainly did. I calibrated it with the solution that came with it. I have a hydrometer that's fairly new I could get a second reading with that I suppose. Have to wait until I'm home unfortunately.

 

[bertoni]

Sometimes, batches of salt products seem to be a bit off, and sometimes the salt settles badly during shipment. Those numbers are a bit strange, but they should be safe enough. You could try mixing the dry salt a bit before making any more saltwater, but it might not help.

 

[Chris918]

Okay hopefully all is okay. I did a 90% change with my new RODI machine's water and that will get rid of the nitrates too I'll test in a few days and see what I get.