Salt Mix Low Calcium / magnesium

[tdburchett]

I recently got a new box of RPM Reef Pro Mix, which I have always used. After a few water changes, I noticed my calcium and magnesium falling faster than expected, so I tested the newly mixed saltwater. I mix at 35 ppt (validated with a weekly calibrated refractometer) using a heater and a mixing pump. The advertised parameters are 8-9 dKH, 400-450 ppm Calcium, 1300-1400 ppm magnesium. The water actually mixes to 8.9 dKH (ok), 350 ppm calcium (very low) and 1140 ppm magnesium (very low). Anyone ever experienced this before? Is it a bad batch of salt, or could I be doing anything wrong with the mixing? I brought the magnesium and calcium up to proper levels with Brightwell Calcion and Magnesion, and plan to use the water for water changes until I figure out the salt mix issue. Any experienced folks see any issue with that? Thank you all.

 

[Randy Holmes-Farley]

There's no mixing issue that leaves alk normal but gives low calcium and magnesium. To precipitate only 20 ppm of calcium takes up 2.8 dKH of alk.

 

[tdburchett]

There's no mixing issue that leaves alk normal but gives low calcium and magnesium. To precipitate only 20 ppm of calcium takes up 2.8 dKH of alk.

Thanks! So probably a bad batch of salt?

 

[Randy Holmes-Farley]

Thanks! So probably a bad batch of salt?

Bad salt or bad tests. Can't tell which.

 

[tdburchett]

Bad salt or bad tests. Can't tell which.

Thanks. I’m thinking bad salt- the Salifert tests showed the exact increase I expected after fixing the parameters with the Brightwell products based on their dosing instructions. Looks like I need new salt!

 

[AFHokie]

Little late but yes, I had this same issue.

I started my tank with RPM and Ca Mg were great but Alk in freshly made water was consistently around 6. I emailed back and forth with Fritz and they sent me a new bag free of charge. This one tested Alk right on around 9 but Ca and Mg were super low. If I remember correctly it was around your values, low 3's for Ca and 11 something for Mg. In fact on the Ca test (salifert) I only made it a drop or two before it would change colors. I tested this a few times over a few small batches. Even dumped and mixed all the salt to be sure.

Even though Fritz had awesome customer service dealing with the first bag I decided to just leave the replacement be and not pursue it. I ended up getting a cheap bag of IO and just dose it up a little bit to hit the Ca and Mg numbers want.

Still debating what to do after my bag of IO is gone....stick with it and dial in my dosing or find another salt.

 

[tdburchett]

Little late but yes, I had this same issue.

I started my tank with RPM and Ca Mg were great but Alk in freshly made water was consistently around 6. I emailed back and forth with Fritz and they sent me a new bag free of charge. This one tested Alk right on around 9 but Ca and Mg were super low. If I remember correctly it was around your values, low 3's for Ca and 11 something for Mg. In fact on the Ca test (salifert) I only made it a drop or two before it would change colors. I tested this a few times over a few small batches. Even dumped and mixed all the salt to be sure.

Even though Fritz had awesome customer service dealing with the first bag I decided to just leave the replacement be and not pursue it. I ended up getting a cheap bag of IO and just dose it up a little bit to hit the Ca and Mg numbers want.

Still debating what to do after my bag of IO is gone....stick with it and dial in my dosing or find another salt.

I ended up thoroughly re-mixing the bag of salt and got better parameters. That said, I decided to swap to Tropic Marin Pro instead since it is supposed to be much more uniform. Since TM Pro has lower Alk, I have been slowly lowering it before swapping. I will start to swap this weekend when I do my water change, so fingers crossed the transition goes smoothly.

 

[AFHokie]

I ended up thoroughly re-mixing the bag of salt and got better parameters. That said, I decided to swap to Tropic Marin Pro instead since it is supposed to be much more uniform. Since TM Pro has lower Alk, I have been slowly lowering it before swapping. I will start to swap this weekend when I do my water change, so fingers crossed the transition goes smoothly.

Good luck. I still have that bag of RPM so I might give mixing another shot.

 

[tdburchett]

Good luck. I still have that bag of RPM so I might give mixing another shot.

Well, I may not be switching to TM Pro after all. My first batch mixed up with 6.5 dKH alc and 1200 ppm mag, both really low (calcium was ok at 420 ppm). My worst batch of RPM had numbers like that, and I had expected much better with TM Pro given its good press on BRS. Doing some thinking about if I actually want to just stick with RPM given TM apparently isn’t all it was cracked up to be.