Is it possible that low magnesium is causing my problems?

Over the last 2 months my calcium has been slowly dropping (420 to 380) and my alkalinity has been slowly rising (13dKH to 18dKH). I have been dosing Reef Fusion 1 & 2 but stopped part 2 (alkalinity) about a month ago. I also do a 20% water change every 7-10 days. Neither of my tests kits (API Saltwater and Reef Master) contain a test for magnesium, so I have not been testing it. I have been doing a little reading tonight and found that magnesium plays a big role in the calcium and alkalinity balance. Could low magnesium be causing this problem.

Edit Add: my other parameters are Temp-79, Salinity-1.025, Ph-8.3, NH3-0, NO2-0, NO3-0, PO4-0

 

Yes,it does help balance cal and alk,best to get your mag to optimal levels (i run mine around 1340ish),which should be right around 3X the calcium level.Get the mag inline first then follow suit with cal and alk so they balance out.

Edit,you'll want to get that alk a little lower before you start raising the mag.I use a red sea mag test kit and use Kent tech-m when needed.

 

If ur doing water changes that often, your mag should be okay.What are your calc and alk #s?

 

Low Magensium could account for your issue
but do not start adding until you have a test kit that you can measure it with

How are you using this product? daily? weekly? and how much are you adding into how much water?
are you allowing adequate time for part 1 to distribute before adding part 2

discontinuing part 2 whilst allowing the DKH to fall was a good idea IMO, whilst continuining to add part 1 in order to bring your Calcium up a bit

ensuring you shake the bottles adequately before adding is also important, because you may not have been adding as much as you thought you had been, if it has settled out of solution

 

Unfortunately most salt mixes have mag at about 1100ppm when you need to be around 1300ppm for stability.

To the OP I would say your issue sounds like low mag. Definitely get a mag test kit post haste.

 

Last week Cal was 380 and Alk was 18. I just did a water change today and normally don't test til the day after to give the system time to equalize. I think I'll try to pick up a mag test tomorrow.

 

How old is the tank?

 

But don't most also list mag at that # with lower salinities than most ppl keep (1.023)? I keep mine around 1.026, which means the concentration will be higher.

 

I dose the fusion every 3rd day. The tank is about 8 mos old. I get my water at the LFS, they claim to use Instant Ocean but I don't know for sure, they fill my buckets in the back room. I have a RO/DI filter that I have not set up yet, that may be project #2 for tomorrow so I can mix my own.

 

Reef Crystals @ 1.021 is 1100 but at 1.026, its 1345.