help me understand my chemistry

[kharmaguru]

I'm not a great tester or maintainer. I'm definitely reactive instead of proactive. My tank is LPS/softie and over the last couple months I have noticed less extension and things generally looking less thrilled to be here. I as a response upped my water changes and generally there is a short lived "happiness" after each one.

Coincidentally I always wanted to know what my PAR levels were and so I had grabbed a Seneye Reef to do some testing. Since it has the 1 month slide I figured I may as well use it. I soaked the slide as required for 48hrs and when put in to service it showed my pH as swinging from 7.55 - 7.73 each night/day. This definitely seemed wrong, considering my auto top up has always been kalkwasser, so I didn't freak out and try to correct it. My only pH test kit was a literally 30yr old API high range kit from my African Cichlid days and it said 8.2. All my test kits were expired so I got new salifert pH, Alk, Ca, Mg and got to testing. This is the result after repeating each test to confirm:

sg 1.023
pH 8.2
dKH 9.3
Ca 360
Mg 930

My conclusion is that the xfactor here is the magnesium? It being low is keeping the calcium down? Or are those numbers in line with that specific gravity (which I am going to start bringing up with my water changes)? Interesting that a 30yr old test kit gave the correct pH reading.

 

[Vinny Kreyling]

Mg has a lot to do with Ca stabilization so bring it up.
Try for 400 or over on Ca.

 

[bertoni]

I would check some freshly-mixed saltwater. 930 ppm for magnesium is quite low, and could indicate a problem with the salt mix or the test kit. The SG is low, as well, and I'd raise it to 1.0264 over a week or so. Topping off with part saltwater should be fine. I'd also get a second opinion on that test equipment before doing much, though. Measurement errors are very common with hobbyist equipment.

 

[kharmaguru]

Thanks for the replies.

I use Instant Ocean. I happened to have a bucket mixed to 1.025 brewing so I tested as you suggested. Mg = 1080. Will have to get another Mg test kit to verify.

 

[awais98]

Regular IO is always low in mag


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[bertoni]

I think IO should be okay for magnesium these days. An older formulation ran around 1100 ppm. Has that changed again?

 

[Vinny Kreyling]

IIRC I git slightly under 1100 on my last check too.

 

[bertoni]

Oh, sigh, that's discouraging.