Magnesium staying on the high side

PiscesPower · Jul 16, 2017

I have a 24g/7g sump mixed reef tank that is about 3.5 months old. I have been using the Red Sea Reef Care program (not strictly adhering with the trace elements) with Nopox dosing and have my Alk & Ca on dosing pump as well.

I have noticed that I have never replaced magnesium, but it stays over 1400 every week. I am using the Red Sea test kits and have had no difficulty in doing them.

I'm curious why I would see no change in my magnesium. I am using Red Sea Coral Pro salt changing about 3 gallons per week. I thought there was a similar uptake of Mag. I replace 1ml of Red Sea Calcium each day.

This week's parameters:
pH -08.26
Temp - 78.8
Ammonia 0.003
Above parameters monitored by Seneye Reef

Ca 390
Alk 8.5
Mg 1440 (Last few weeks: 1440, 1480, 1480)
Nitrate - 0
Phos - .04

I do have the start of some browny/Green hair algae on my glass so I am assuming my Nitrates/Phos are a bit higher.

Randy Holmes-Farley · Jul 16, 2017

Magnesium consumption is very slow. Max rate is about 10% of the consumption rate for calcium, and often much less. So often 1 ppm per day is about as much as you'd see, and since many mixes have very high magnesium, water changes can often offset it.

That said, the Red Sea magnesium kit often reads incorrectly high.

1MJG1 · Jul 16, 2017

Also every tank is different. I dose 20 ml magnesium/day to keep me around 1500.
Ca and KH I dose 50 mL/day to keep 420 and 9.5. I only have. 50 gal tank too. So like I said every tank is different just keep track and an eye on what parameters your tank likes best. If your getting green algae up the mg and see what happens.

PiscesPower · Jul 16, 2017

1MJG1 said:
Also every tank is different. I dose 20 ml magnesium/day to keep me around 1500.
Ca and KH I dose 50 mL/day to keep 420 and 9.5. I only have. 50 gal tank too. So like I said every tank is different just keep track and an eye on what parameters your tank likes best. If your getting green algae up the mg and see what happens.

Why do you aim for 1500?

AdamNC · Jul 16, 2017

When was the last time you really cleaned you Mag test vial. I used to be all over the map until I started cleaning the vial every time before testing, then rinsed real good with ro/di. Since then I've had no issues with the Red Sea Pro test kit.

chipmunkofdoom2 · Jul 16, 2017

Your bucket of RSCP should have a table that lists the target concentration for magnesium at different salinities (the BRS listing has a picture of the bucket if you no longer have yours). Note that at 35ppt salinity, Red Sea states the Mg will be between 1,360 and 1,420 mg/L. That's right about what your test kits are saying.

It's possible your magnesium stays consistently high because your tank uses so little of it and your salt mix contains so much. Either way, I wouldn't worry. There's nothing wrong with magnesium levels of 1,440ppm.

PiscesPower · Jul 17, 2017

AdamNC said:
When was the last time you really cleaned you Mag test vial. I used to be all over the map until I started cleaning the vial every time before testing, then rinsed real good with ro/di. Since then I've had no issues with the Red Sea Pro test kit.

I clean it every time with RO/DI after I use it.

rstrann · Jul 17, 2017

My Mg levels are around 1500 and sometimes more in my sps dom 180. Doesn't cause any issue from what I can tell.

AdamNC · Jul 17, 2017

PiscesPower said:
I clean it every time with RO/DI after I use it.

Sometimes ro/di is not enough with the haze it leaves behind. Before every test I clean out the vial with vinegar and a q-tip and then an ro/di rinse. Try to test it after a regular rinse and then try testing after the vinegar cleaning. I've found 2 way different readings this way.

Maacc · Jul 17, 2017

@Randy Holmes-Farley which mag test kit do you recommend?

Ashish Patel · Jul 17, 2017

That said, the Red Sea magnesium kit often reads incorrectly high.[/QUOTE]

I use Redsea Mg Test kit and have been reading 1440 for the past 1 month.. I suspect its high having not done many waterchanges. Which test kit is more accurate? I believe I used saliferts in the past but i bought this redsea pro kit since it was included.