Magnesium is OUT OF CONTROL!, and low nutrients HELP!

[MV17]

I have a 40g breeder with Fiji-24 Advanced Reef Sump beneath it. I run two felt filter socks, a Z-6 Bubble Magnus skimmer running 24/7 with a relatively dry skim, and a refugium with chaeto and a grow light on for 8 hours during the day. The GHA in my tank is out of control and I can't seem to grow any coralline algae. (I am planning to get a tuxedo urchin to control the GHA even though that will further hinder the coralline algae growth even if there was any.) The tank is relatively stable as it has been up and running for over a year. I haven't tested in a while, but I did today and realized that my magnesium was out of control. I even tested my Salifert magnesium test kit and it was spot on. Do you think the high magnesium and low nutrients are affecting my algae growth? My params are below...

Temperature: 80F
pH: 8.0
Ammonia: undetectable
Nitrite: undetectable
Nitrate: undetectable
Alkalinity: 8.6
Phosphate: undetectable
Calcium: 480
Magnesium: 1680

 

[MNFish]

I would not worry about high magnesium, and nutrients are probably low because algae is consuming all of it. I would try to pick off as much algae as possible.

 

[MV17]

Ok I’ve read that high mag is bad for inverts though. I have 3 large and 4 small narcissus snails, at what point does it become fatal?

 

[Garf]

I have a 40g breeder with Fiji-24 Advanced Reef Sump beneath it. I run two felt filter socks, a Z-6 Bubble Magnus skimmer running 24/7 with a relatively dry skim, and a refugium with chaeto and a grow light on for 8 hours during the day. The GHA in my tank is out of control and I can't seem to grow any coralline algae. (I am planning to get a tuxedo urchin to control the GHA even though that will further hinder the coralline algae growth even if there was any.) The tank is relatively stable as it has been up and running for over a year. I haven't tested in a while, but I did today and realized that my magnesium was out of control. I even tested my Salifert magnesium test kit and it was spot on. Do you think the high magnesium and low nutrients are affecting my algae growth? My params are below...

Temperature: 80F
pH: 8.0
Ammonia: undetectable
Nitrite: undetectable
Nitrate: undetectable
Alkalinity: 8.6
Phosphate: undetectable
Calcium: 480
Magnesium: 1680

Perhaps your salinity is higher than you think it is.

 

[Duffer]

My mag goes high at times and has not hurt any inverts…but you are getting false readings in your nutrients especially phosphate as the algae is consuming and feeding off of it

 

[GoVols]

Your high mag is not that bad, but could slow down snails. It would have nothing to do with algae growth.

One thought:
If you look close, the algae is just on your rock work, so the rock could be leaching phosphates.

That algae on your scape, including your fudge could be sucking in your phosphates and nitrates. That could lead them to be undetectable in your water column with test kits.

 

[MV17]

Perhaps your salinity is higher than you think it is.

YEP! I just recalibrated my refractometer, turns out it was way off...the specific gravity is 1.028! Is the best course of action to slowly replace it with RODI water or should I do a large change right now?

 

[MV17]

Your high mag is not that bad, but could slow down snails. It would have nothing to do with algae growth.

One thought:
If you look close, the algae is just on your rock work, so the rock could be leaching phosphates.

That algae on your scape, including your fudge could be sucking in your phosphates and nitrates. That could lead them to be undetectable in your water column with test kits.

How do I get the rocks to stop leaching phosphates? Wait it out?

 

[Garf]

YEP! I just recalibrated my refractometer, turns out it was way off...the specific gravity is 1.028! Is the best course of action to slowly replace it with RODI water or should I do a large change right now?

I’d do it slowly over a few days. It’s about 10% of your water volume to replace with RODI.

 

[GoVols]

How do I get the rocks to stop leaching phosphates?

You can’t

Time to bring in a big cleanup grew…

Always had good experiences when buying from reef cleaners

Reef Cleaners - Clean up Crews and Macroalgae

We specialize in algae eating invertebrates, natural filtration, and algae solutions for saltwater aquariums.

www.reefcleaners.org

 

[MV17]

You can’t

Time to bring in a big cleanup grew…

Always had good experiences when buying from reef cleaners

Reef Cleaners - Clean up Crews and Macroalgae

We specialize in algae eating invertebrates, natural filtration, and algae solutions for saltwater aquariums.

www.reefcleaners.org

What would you recommend for a CUC besides the narcissus snails and the tuxedo urchin I plan to get (or should I skip the urchin)?

 

[Jekyl]

What would you recommend for a CUC besides the narcissus snails and the tuxedo urchin I plan to get (or should I skip the urchin)?

Check out reefcleaners.org for a cleaner package. Also, if using API tests it's time for an upgrade. Ammonia and nitrite tests aren't needed anymore.

 

[MV17]

Check out reefcleaners.org for a cleaner package. Also, if using API tests it's time for an upgrade. Ammonia and nitrite tests aren't needed anymore.

I use all salifert… and I will make sure to check out the packages!

 

[Jekyl]

I use all salifert… and I will make sure to check out the packages!

By far cheaper than your LFS and great for diveristy.

 

[Randy Holmes-Farley]

How do I get the rocks to stop leaching phosphates? Wait it out?

With no detectable phosphate in the water, the rocks may or may not have much phosphate on them, but there's nothing I would do.

I'd even consider adding some N and P (or more fish food) to avoid risking dinos.