Discussion in 'Reef Aquarium Discussion' started by Jeremy Lain, Feb 8, 2018.
Hello, magnesium low in reef tank. Test says 1160 ppm. What to do to bring it up?
What kit and what salt mix and salinity?
I am using an red sea reef foundation pro test kit for testing magnesium and an api test kit for all the other water perameters. I am going to attach a picture of my water perameters. I am using instant ocean sea salt.
The only way I could keep calcium and dkh on the right levels was to bring my salinity down to 1.019. I have read that it needs to be higher but it's not working for me with the peraeters needed.
Thats because your mag is so low. Bring it up slowly by using a magnesium supplement, restest the pther two parameters. They should also come up. Instant ocean has lower mag then some others. Reef crystals has an elevated magnesium number. Get your mag up amd the other two are easier to keep at stable levels. Get you SG up to 35ppm slowly now as well. Over a few days.
There are a number of possible inconsistencies here: salinity measurement seems like it may be off, low salinity, and a possibly faulty magnesium kit.
Lowering salinity below normal is not the way to bring a parameter (other than salinity) into line because it drops everything.
That said, I doubt the salinity is accurate if calcium and magnesium are still that high. They would be much lower with IO at that salinity.
The salinity is the reason you magnesium is too low (well, one reason, anyway). That kit is also faulty in many peoples hands.
1160 ppm at a sg of 1.019 will have a magnesium level of 1611 ppm at 35 ppt (sg = 1.0264).
there are supplements you can use to help bring it up. Good magnesium levels make it easier to keep ca up for the most part.
I think your salinity meter is way off. In 1.019 I doubt your corals will survive in such a low sailinity.
Testing procedure for Reef tanks:
4. Calcium and Magnesium
So please take a sample of your water to a reefer in your neighbourhood and test your salinity first.
Agree with all other posters. Salinity is a combination of all components in the water including calcium, magnesium, strontium, etc, etc. Low salinity means lower values for all the above. Randy makes a good point that if salinity is truly 1.019 then calcium would typically be lower so I suspect testing error is playing out here too. The API Calcium test kit is not very accurate compared to other quality tests.
Verify salinity first. Then get it up to a proper level slowly so as to not stress your livestock, then retest magnesium. I would NOT add magnesium supplements until you do the above. I suspect your magnesium level is okay as is.
Can you help me understand how you got this calculation? "1160 ppm at a sg of 1.019 will have a magnesium level of 1611 ppm at 35 ppt (sg = 1.0264)"? Is there some way they are connected together to equal certain levels? I mean like if one is low are the others affected? The Calcium, DKH, Magnesium, and Possibly PH?
When you raise salinity by allowing evaporating or adding salt mix, you boost everything in the water (not pH, it isn't controlled that way).
Concentrations are about linear with the specific gravity (ignoring the leading 1) or the salinity in ppt.
So, for example, if magnesium is at 1160 ppm at a specific gravity of 1.019 and you allow the water to evaporate down to a specific gravity of 1.0264, the magnesium will rise by a factor of 26.4/19 (the values from the specific gravity change) = 1.39.
So 1.39 x 1160 = 1612 ppm
The answer is similar if you top off with salt water to replace evaporation and let the salinity rise in the tank.
They are not tightly and directly connected the way some reefers think, but calcium carbonate can preciptiate from seawater, and that can happen if you push up alk, or calcium, or pH. When that happens, both calcium and alk can decline. Magnesium deters the precipitation.
This has more:
A Simplified Guide to the Relationship Between Calcium, Alkalinity, Magnesium and pH by Randy Holmes-Farley - Reefkeeping.com
Years ago i was sure i was having a Ca problem the test kit i was using ended up being expired like a year, i think i bought it expired and never noticed. Double check kit? Maybe a bad batch of salt mix idk.
My water keeps evaporating. Do you think this might be happening because the wrong parameters are in the tank,(Calcium, DKH, Magnesium)?
I recommend you get s.g. up to 1.025 then retest.
And use the dr Randy holmes-farley diy 2 part methods. see: http://reefkeeping.com/issues/2006-02/rhf/index.php
but that's just me and my .02
That was a cool article! Thank you.
My ph is at 7.8 like you said and calcium 420 alkalinity 8.75 and magnesium 1260. So I will be learning more about how to raise ph. Do you know if this will help with coralline algae growth?
SeaChem Magnesium is very potent and fairly inexpensive. For PH drop, increase surface agitation for better gas exchange, and run alternating light schedules for the sump and tank. Add small amounts of buffer or sodium hydroxide or soda ash to raise PH.
For the SeaChem Mg. You dissolve 1 tsp. per 20g of water every two weeks once you have it up to 1350-1450. I switched to it from Brightwell due to cost. I was going through a large bottle of Brightwell Mg. a week and fighting to keep mine above 1200. Two doses with SeaChem Mg. and my 75g hit 1450 and has been stable there by adding it to my top off container. Since raising it the coraline in my tank has taken off like crazy.
are you testing pH just before lights out? Ph will rise lights on and decrease lights out. Due to algae consuming co2. To my what is important is the just before light out. If at normal or high levels that indicates the co2 is being fully consumed by the algae. My PH used to be 8.4 light on then drop to 7.9 lights out. Eventually I bumped up alk with baking soda and the drop was much less.
I just tested it this morning and it is at 7.8 with the lights on? Do you think I should bring the alkalinity up a little bit and see if it helps?
what is it just before lights out?.
you could also bump up alk to 10dkh with baking soda to see if that helps.
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