Max Manesium Dosing per day

pinocchio · Dec 6, 2023

I recently tested my Mg and am very low. I’m needing to add close to 1000ml (raising about 500ppm) to my 90 gallon tank and wondering what the most I can add a day SAFELY. If I just raise it by 10ppm a day it will take forever. What is the max I can raise it? How often?

FUNGI · Dec 6, 2023

I read somewhere 20ppm, however, I am in the same boat as you and I dose max 20ml for a 120G using SeaChem mag. Try using this:

Magnesium Dosing Calculator

www.saltwateraquarium.com

or

Magnesium Supplement Calculator - Bulk Reef Supply

Bulk Reef Supply - Saltwater Aquarium Supplies for Reef Tanks

www.bulkreefsupply.com

FUNGI · Dec 6, 2023

and I think the the bottle should say max daily dose

rtparty · Dec 6, 2023

I would be shocked to find that you are truly 500ppm short. Magnesium simply isn’t used up in our systems that quickly

FUNGI · Dec 6, 2023

rtparty said:
I would be shocked to find that you are truly 500ppm short. Magnesium simply isn’t used up in our systems that quickly

I would have thought the same until I tested.....I was at 1080ppm.....

pinocchio · Dec 6, 2023

Testing with salifert tester, testing twice after a water change, I am at 960. I was told to shoot for 1400.

rtparty · Dec 6, 2023

FUNGI said:
I would have thought the same until I tested.....I was at 1080ppm.....

Just say NO to magnesium testing: RMM is born

OK, this thread has been many years in the making, and I'm posting it here since folks in the chem forum are probably already tired of all the threads relating to problematic magnesium testing. I'm going to propose a method, let's call it the Randy Magnesium Method, or RMM for short. All good...

www.reef2reef.com

You would have to have crazy coralline growth and be doing zero water changes for quite a while. Magnesium test kits are one of the most unreliable and inaccurate testing kits we have

pinocchio · Dec 6, 2023

rtparty said:
Just say NO to magnesium testing: RMM is born

OK, this thread has been many years in the making, and I'm posting it here since folks in the chem forum are probably already tired of all the threads relating to problematic magnesium testing. I'm going to propose a method, let's call it the Randy Magnesium Method, or RMM for short. All good...

www.reef2reef.com

You would have to have crazy coralline growth and be doing zero water changes for quite a while. Magnesium test kits are one of the most unreliable and inaccurate testing kits we have

I had been neglecting water changes for a couple months since other parameters were seeming fine.

rtparty · Dec 6, 2023

pinocchio said:
I had been neglecting water changes for a couple months since other parameters were seeming fine.

If we assume your tank is super high demand and uses 1ppm magnesium per 10ppm calcium, you would have had to gone through 2,500 to 5,000ppm of calcium in the last couple months.

How old is your tank and how packed with coral?

pinocchio · Dec 6, 2023

rtparty said:
If we assume your tank is super high demand and uses 1ppm magnesium per 10ppm calcium, you would have had to gone through 2,500 to 5,000ppm of calcium in the last couple months.

How old is your tank and how packed with coral?

For reference my other parameters as of today are:

Calcium- 360
Phos- .09
Alk - 9.3
Nitrate - 9.1

Only corals in tank are 3 different types of zoas, about 50-60 polyps total. 1 framer with 2 heads, and a dying frogspawn which was 5 heads, but has been dying slowly and is done to 2 heads which is why I am trying to find out what’s going on.

Tank is about 1 year old.

rtparty · Dec 6, 2023

pinocchio said:
For reference my other parameters as of today are:

Calcium- 360
Phos- .09
Alk - 9.3
Nitrate - 9.1

Only corals in tank are 3 different types of zoas, about 50-60 polyps total. 1 framer with 2 heads, and a dying frogspawn which was 5 heads, but has been dying slowly and is done to 2 heads which is why I am trying to find out what’s going on.

Tank is about 1 year old.

I would start with a couple decent water changes to get levels back up. Then test again and have your levels double checked by a store or local hobbyist if you can

Randy Holmes-Farley · Dec 7, 2023

Try your mag test on new salt water and double check salinity measurements before doing a very extreme thing like raising magnesium by 500 ppm. IMO, it is unlikely to be that low for the reasons rtparty indicated.

pinocchio · Dec 7, 2023

rtparty said:
I would start with a couple decent water changes to get levels back up. Then test again and have your levels double checked by a store or local hobbyist if you can

How frequent should these decent water changes be?

Seansea · Dec 7, 2023

My tank goes thru mag about 20 ppm every 7 days or so. And have since day 1 on this tank at a full year now. Use salifert as well and have checked with icp and its spot on. I do have good corraline growth but think its something to do with my algae scrubber.

When using salifert i put the vial up to the window and make sure the color turns to true blue. Dont go with that grey thing the directions suggest. As far as raising i think 30 ppm per day is safe to do. Get it to around 1250 then can go a little slower.

What salt are you using? Reef crystals is wildly inconsistent on mag. Ive had it as high as 1400 and as low as 1050 on different buckets. Test each new bucket. If i have a bucket thats low i add mag in for my water change.

Euphelia will def suffer when mag gets low. Mine were shrunk in and now that my mag stays around 1400-1450 and they are doing much better.

Randy Holmes-Farley · Dec 7, 2023

pinocchio said:
How frequent should these decent water changes be?

None, unless you determine your kit shows much higher magnesium in the new salt water.

Randy Holmes-Farley · Dec 7, 2023

Seansea said:
My tank goes thru mag about 20 ppm every 7 days or so.

Which is reasonable if you also have very high alk and calcium additions (4 dKH per day, 28 ppm calcum per day).

If you do not, then that is not accurate, and it is certainly cannot be the case in a tank like the OP has, where there are no ongoing calcium and alk additions.

The ONLY way magnesium is depleted is by codeposition into calcium carboante, and the magnesium is never more than about 1/10th of the calcium uptake, often much lower.

kevgib67 · Dec 7, 2023

Randy Holmes-Farley said:
Try your mag test on new salt water and double check salinity measurements before doing a very extreme thing like raising magnesium by 500 ppm. IMO, it is unlikely to be that low for the reasons rtparty indicated.

I agree, I use the same test kit and my magnesium was running low. I use Fritz RPM which states magnesium should mix to 1350. I tested a fresh batch and it was right on, 1350. I then began to dose magnesium.