High Magnesium & Calcium

[Fishies :)]

Hi, I've been having this issue since I started my tank in around April. It seems as though the magnesium and calcium are very high. I've tried the Salifert and Red Sea pro test kits for Magnesium, and for Calcium I've tried the API, Salifert, and Red Sea pro test kits. I've consistently measured over 500 calcium and over 1600 Magnesium. I do a 15% water change weekly and I don't dose anything currently. The salt I've been using is instant ocean sea salt, so supposedly the levels should be 400 Calcium and 1320 Magnesium. Originally I figured it wasn't a huge issue since nothing seemed to be suffering in my aquarium. I assumed the salt batch just had high levels but I just bought a new bucket of salt and I'm still getting over 500 calcium and over 1600 magnesium. So it doesn't seem likely that I got 2 faulty batches of salt in a row. It also doesn't seem likely that all 2 or 3 of the test kits I've tried are faulty, they are all well within their best before dates of 2024 as well. Yesterday I tested my RODI water before adding salt and I actually still got >500 Calcium and >1600 magnesium so I'm thinking it might just be the water here? Shouldn't my RODI filter be removing it though? Appreciate any ideas/assistance, ideally I'd like the magnesium and calcium to be lower so I can control it with a doser but I guess there are worse issues I could have.

Edit: I checked and apparently my City's water levels for Magnesium at 16.7ppm, and for Calcium is around 52 ppm. So it seems unlikely that it's the city's water supply, I may just have 3 faulty tests.. I'm considering getting a hanna checker for Calcium but I'm not sure what I can get for Magnesium that is more trustworthy than the Red Sea or Salifert tests.

 

[shwareefer]

What is your salinity and how are you measuring it?

 

[Fishies :)]

What is your salinity and how are you measuring it?

My salinity is 1.026, I'm using a refractometer that I calibrate every time I measure

 

[Spieg]

My guess would be your salt mix is high in those components.

 

[X-37B]

If your new salt makeup is showing those levels then thats where its comming from.
IO, which I use, gives me ca 420 and mag 1350 after lowering alk from 11.5 to 7.5.

 

[Fishies :)]

If your new salt makeup is showing those levels then thats where its comming from.
IO, which I use, gives me ca 420 and mag 1350 after lowering alk from 11.5 to 7.5.

I use IO, and as I said I've tested 2 IO batches (Like, 2 separate containers) and pre-salted RODI water and still got >1600 mag and >500 calcium. I am thinking it could be faulty test kits but I've used 3 calcium test kits and 2 magnesium test kits, none are expired or near expiry. I'm at a loss

Edit: My alkalinity is ~9.5 if that matters

 

[X-37B]

My guess is if the readings are accurate its Reef Crystals instead of regular.

Maybe a mixup at the factory but 2 buckets?
Maybe check lot numbers.

Reef crystals can mix close to those levels.

Also I have heard of mixing the bucket up before use leads to better levels.

I always just scoop it out of the bucket so?

 

[dwest]

It makes no sense that your RODI water has high calcium and magnesium. Take your samples of RODI and aquarium water to a fish store or other hobbyist. It seems to me that it has to be a test problem or your RODI unit is plumbed so you are collecting waste water. Do you check the TDS of the input and output RODI water?

 

[Fishies :)]

It makes no sense that your RODI water has high calcium and magnesium. Take your samples of RODI and aquarium water to a fish store or other hobbyist. It seems to me that it has to be a test problem or your RODI unit is plumbed so you are collecting waste water. Do you check the TDS of the input and output RODI water?

Will do, hopefully the LFS can figure it out, I'm banking on a string of unfortunate tests. I have never checked the TDS or output of the water

 

[Fishies :)]

Update: I think when I tested the fresh RODI water I just messed up somehow, I tested again last week and it was 0 mag/calcium. I took my aquarium water in to the fish store near me and they confirmed that the values were super high so I've got the red sea blue bucket instead, it seems like I just got 2 bad batches of IO in a row unfortunately.. Thanks for the help

 

[Tailfisher]

If your new salt makeup is showing those levels then thats where its comming from.
IO, which I use, gives me ca 420 and mag 1350 after lowering alk from 11.5 to 7.5.

What are you using g to lower alk from 11.5 to 7.5 . Just curious

 

[X-37B]

What are you using g to lower alk from 11.5 to 7.5 . Just curious

Sodium bisulfate
Just did 18 gallons.
12 for my 120 wc
6 for my 45 frag system

 

[wolfen281]

Update: I think when I tested the fresh RODI water I just messed up somehow, I tested again last week and it was 0 mag/calcium. I took my aquarium water in to the fish store near me and they confirmed that the values were super high so I've got the red sea blue bucket instead, it seems like I just got 2 bad batches of IO in a row unfortunately.. Thanks for the help

Hi- I know this is a few months old, but I just started my first tank several weeks ago and have been using Instant ocean. My Ca and Mg levels are as you described. I have to dilute the tank water 1.25X to even be able to read the levels.
I also have 2 different test kits for Mg and Ca because I thought the kits were bad, or I forgot how to titrate (for reference...I'm a lab rat and have titrated a time or 2).
Anyways...my 02. My 2 clowns are kewl with it but curious as to how corals will do.
Cheers!
Kim