Cal,all,mag,ph levels

[Startingover]

Ok, I set my tank up about 6weeks ago. 120gal/39gal sump. Cycled with 80lbs live rock. Complete cycle with nitrates at 25(after 2large water changes 42/30gal)
Parameters:
PH-7.8(considering airline tube from outside window to skimmer inlet)
Tank is in basement.
CAL-405
ALK-6.3
MAG-1260

Now, The parameters of the freshly mixed salt prior to 30 gal water change.
PH-8.5
CAL-490
ALK-8.2
MAG-1420

Tests with Salifert kits, Hanna PH/ALK testers.

What is causing, the drop in values once in my tank?
Was running gfo/carbon. Stopped the gfo today.
I have my diatom outbreak currently. Just can't understand why the parameters are so off on a new "coral less" tank??

Any help appreciated.

 

[thegrun]

You will naturally get some calcium precipitation in any tank, if you have any coraline algae growing it will lower your alkalinity and calcium and the GFO will definitely lower them.

 

[downbeach]

What are you using to measure your salinity with? If a swing arm type of hydrometer, it may be giving you both incorrect and inconsistent readings, and by extension varying amounts of Ca, Alk, Mg, etc. Are you using RO/DI water? If you're not already doing so, I would suggest using a decent refractometer that is properly calibrated using a seawater calibration solution @ 1.026(35ppt)(not plain water).

 

[Dkuhlmann]

You don't say what your salinity is, without showing what it is I'm going out on a limb and say that your two test result differences are due to different sg. Your salt mix should match pretty closely to what is on the bag or bucket for your readings of Ca/Mg/Kh etc.

I'll second the suggestion for getting a refractometer and 35pt 1.026 calibration fluid. Never use plain water to calibrate your equipment. The swing arms do work but you have to make sure there are no air bubbles on the arm. Not only that but due to different temps they can be off. It is best to use the refractometer and you can get them fairly cheap on Ebay.

 

[Startingover]

Using a refractometer for sg of 1.025.
Yes I'm using BRS value+ RODI water.
Salt is RPM salt by Fritz.
Salinity freshly mixed water was 1.030. High I know but my tank was at 1.023, so I was trying to overshoot a little to bring the rank to 1.025 which it did.
Thanks

 

[That New Guy]

If the salinity was higher in the fresh water you tested, all other parameters will also be higher. Make a new batch to the right SG and test again.

 

[Capsle]

Also make sure your refractometer is properly calibrated. Using fresh RO water it should read 0 at the bottom of the looking glass. The line should be dead on the zero Mark.


Sent from my iPhone using Tapatalk

 

[Startingover]

The refractometer was purchased from LFS in Indy and the owner calibrated it with calibration fluid. I just don't understand why the parameters in the freshly mixed water were within range, then once added to the tank they are way low?
Is it because of the diatom bloom? I just don't want to keep doing 25-30% water changes and the parameters stay the same?? I Never ran into this with my last tank.

 

[thegrun]

It is because the water had different salinity levels. If your salinity is higher in your water change water than your tank water all the parameters will also be higher.

 

[Timfish]

You need to consider the biology in your aquarium is already using the stuff. Bicarbonates, for example are critical for photosynthesis (along with phosphate).

 

[Startingover]

Thanks

Thanks

I guess I didn't think I would need to start dosing kalk or two-part this early. Thank you for all the help. I'm going to do another 30gal WC and check again. If the alk, mag, cal levels are still low I will start dosing something.