Alkalinity rising?

[pdiehm]

My tank has been running a zeovit system for a while and we all know the recommended parameters of 7.0 to 7.5 alkalinity.

I am using the Red Sea salt in the blue bucket, mixed at 1.0235 has an alkalinity of 7.7. This was confirmed by me as I tested it using the Hanna dKh at 7.8 and Red Sea test at 8.0.

Started to make water at this salinity 3 weeks ago and 45 gallons have been changed out of 120.

My Alkalinty has gone from 8.1 to 8.3 to 8.7 to 9.0 (today). Red Sea Alk test came up at 9.3. Salinity is at 1.025.

So what am I missing? My corals are growing. Pretty colorful. No alkalinity burns. Yet instead of alkalinity being used, it seems it's being increased somehow.

 

[SPS_]

Are you dosing anything in the tank? Or trying to adjust ph ?

 

[pdiehm]

Not dosing anything. My pH is a constant 8.1-8.3.

 

[SPS_]

Not to be rude, but are you reading the test backwards? The titrant used. Maybe someone more knowledgeable will chime in.

 

[pdiehm]

It's hard to read the digital Hanna dKh test wrong. 9.0

I think since I am so lightly stocked I may stop water changes for a few weeks and see what happens.

I also wonder if my pH probe needs to be recalibrated (apex)

 

[twilliard]

I would study the salt a little deeper.

 

[pdiehm]

Last test of new salt mix:

1.024
7.7
420 calcium
1320 magnesium.

Pretty much inline with what is on the label.

Will order some calibration fluid for my apex ph probe and maybe use the lab grade that I have instead of the regular.

 

[pdiehm]

I think I may have found the problem. My digital refractometer wasn't calibrated right...I don't think.

My tank tested out at 1.016, which I know isn't right. I recalibrated and retested. Came out at 1.026, which is odd because I have been "making" it at 1.024 the last few changes. So it shouldn't be 1.026, probably in the 1.0245 range. According to Red Sea at 1.026, the range is 8.7-9.1.

Will keep tabs on it.

 

[Randy Holmes-Farley Verified Community Expert]

OK, good luck!

 

[GainesvilleReef]

My digital refractometer needs to be re-calibrated every time you use per the instructions. It's easy to do with RODI water. I check it against calibration fluid and it's spot on every time. The one thing that is important about all refractometers is to keep them clean. I clean my unit with RODI after every use.

 

[pdiehm]

My digital refractometer needs to be re-calibrated every time you use per the instructions. It's easy to do with RODI water. I check it against calibration fluid and it's spot on every time. The one thing that is important about all refractometers is to keep them clean. I clean my unit with RODI after every use.

Yeah. The thing I don't do is really clean it after use, but if you calibrate with 1.000 (RODI) isn't that the same thing as cleaning it?


Now that I am done coaching baseball, I can stay more on top of this. Don't get me wrong...everything looks great and growing. Just seems odd that as things grow, my alkalinity is climbing

 

[GainesvilleReef]

If it has dried salts from the last reading it can screw up you calibration. It only takes 2 seconds to do.

 

[pdiehm]

9.3. Starting to see some corals closing up.

Not entirely sure how I can fix the alkalinity without screwing with the salinity too much. You would think the 2 15g changes at 1.024/7.7/410/1320 would have made some what of a difference but it hasn't. My salinity has actually gone up, my Alk has gone up, but the calcium and magnesium have come down.

 

[Randy Holmes-Farley Verified Community Expert]

What is 9.3? The alk in dKH? That's certainly fine.

 

[pdiehm]

Even for an ULNS?

 

[Randy Holmes-Farley Verified Community Expert]

Might be a bit high for ULNS. I didn't see numbers, but I should have noticed the zeovit.

You can lower the alk with a mineral acid if you want.

 

[pdiehm]

Was told to wait a few weeks for a water change and let it come down naturally. I am so lightly stocked (10 corals or so, and 3 fish) that I should be ok

 

[Randy Holmes-Farley Verified Community Expert]

OK, good luck!