All for Reef only raising Alk

[Rick's Reefing Adventures]

Hey,

About three months ago, I started dosing AFR because water changes alone could no longer keep up with the demands of my tank. Once I got the parameters stable, I stopped doing water changes altogether. Everything seemed fine, so after a few weeks I reduced my testing to just Alkalinity, Nitrate, and Phosphate.

I have a 25G Euphyllia-dominant tank, and recently I’ve noticed reduced polyp extension. After running a full set of tests, I discovered that my Magnesium had dropped to 1220 ppm and Calcium to 380 ppm—both significantly lower than their previous levels (Magnesium ~1400 ppm and Calcium 460–480 ppm). Alkalinity has remained stable throughout.

Does anyone have tips or suggestions? I’ve just manually dosed Magnesium (added 50 ppm for now) and I’m hoping that helps.

 

[gbroadbridge]

Hey,

About three months ago, I started dosing AFR because water changes alone could no longer keep up with the demands of my tank. Once I got the parameters stable, I stopped doing water changes altogether. Everything seemed fine, so after a few weeks I reduced my testing to just Alkalinity, Nitrate, and Phosphate.

I have a 25G Euphyllia-dominant tank, and recently I’ve noticed reduced polyp extension. After running a full set of tests, I discovered that my Magnesium had dropped to 1220 ppm and Calcium to 380 ppm—both significantly lower than their previous levels (Magnesium ~1400 ppm and Calcium 460–480 ppm). Alkalinity has remained stable throughout.

Does anyone have tips or suggestions? I’ve just manually dosed Magnesium (added 50 ppm for now) and I’m hoping that helps.

If your calcium demand is not adequately maintained by AFR simply manually adjust periodically using Calcium Chloride.

Same for Magnesium using Magnesium Chloride, however keep in mind that Magnesium tests are notoriously inaccurate.

 

[Rick's Reefing Adventures]

If your calcium demand is not adequately maintained by AFR simply manually adjust periodically using Calcium Chloride.

Same for Magnesium using Magnesium Chloride, however keep in mind that Magnesium tests are notoriously inaccurate.

If I need to dose 2 of 3 elements seperately that kind of defeats the purpose of AFR haha. If that’s the case I’ll switch to 3 part or something like that. Sadly I just bought a new bottle…

Magnesium tests might not be very accurate, but a 1400 to 1220 dip is too big of a difference IMO.

 

[gbroadbridge]

If I need to dose 2 of 3 elements seperately that kind of defeats the purpose of AFR haha. If that’s the case I’ll switch to 3 part or something like that. Sadly I just bought a new bottle…

Magnesium tests might not be very accurate, but a 1400 to 1220 dip is too big of a difference IMO.

I would think topping up Ca and Mg once every month or two is simpler than running a 3 head doser and maintaining 3 sets of solutions.

Keep in mind as well that coral will thrive over quite a wide range for both as they are not as critical as Alkalinity.

I use AFR on my nano, test Ca every couple of months and adjust if necessary.
I don't bother about testing or adjusting Magnesium

For my large tank, I use a 3 part as AFR is too expensive.

 

[Randy Holmes-Farley Verified Community Expert]

There’s no chance that if AFR alone is maintaining alk, that it won’t maintain calcium against coral consumption unless water changes with a mix not matching the tank are messing with demand ratios.

But like any balanced additive, if you raise alk by 2.8 dKH with AFR, the calcium rise is quite small, only 20 ppm.

As mentioned above, boosting calcium with calcium chloride is a fine plan to
Boost calcium, when needed. AFR alone is not a good way to raise calcium because alk will rise too much.

 

[gbroadbridge]

the calcium rise is quite small, only 20 dKH.

^^^^^
20 ppm :)

 

[Randy Holmes-Farley Verified Community Expert]

^^^^^
20 ppm :)

lol, yes

 

[rishma]

Randy covered it. All the required calcium and magnesium are dosed with the alk in AFR. There is actually a slight excess of calcium, it’s very common for calcium levels to rise slightly over time.

2 things- salinity and test error.

Salinity: if your salinity is low, your calcium and magnesium will be low. Do some searches on salinity in this forum. You’ll find many commercial calibration solutions are wrong, leading to wrong measurements from refractometers. You can make an accurate DIY calibration solution with table salt or Tropic Marin hydrometers are generally considered reliable.

Test error: I find Calcium at home tests to be problematic so I don’t do them anymore. I test a couple times a year with ICP. Magnesium tests are notoriously inaccurate so Randy doesn’t recommend testing at home at all and many of us do not.

 

[LunaReefs]

Randy covered it. All the required calcium and magnesium are dosed with the alk in AFR. There is actually a slight excess of calcium, it’s very common for calcium levels to rise slightly over time.

2 things- salinity and test error.

Salinity: if your salinity is low, your calcium and magnesium will be low. Do some searches on salinity in this forum. You’ll find many commercial calibration solutions are wrong, leading to wrong measurements from refractometers. You can make an accurate DIY calibration solution with table salt or Tropic Marin hydrometers are generally considered reliable.

Test error: I find Calcium at home tests to be problematic so I don’t do them anymore. I test a couple times a year with ICP. Magnesium tests are notoriously inaccurate so Randy doesn’t recommend testing at home at all and many of us do not.

Been using the Milwaukee from day one. I don't trust anything else.

 

[rishma]

Been using the Milwaukee from day one. I don't trust anything else.

I assume you are referring to milwauakee salinity calibration fluids? Probably ok but based on reading here I’ve lost confidence in hobby calibration fluids. I blame @Randy Holmes-Farley

 

[Randy Holmes-Farley Verified Community Expert]

I accept that blame. lol