3 mag recipes

[salty joe]

I saw one mag recipe of 3 cups Epsom with 5 cups Mag flake, another 8 cups Epsom and another 7 1/4 cups Mag flake with 3/4 cup Epsom.

All three recipes were mixed into a gallon of water and yielded 47,000 ppm mag.

IIRC, I read the best recipe to use with a calcium reactor is the 7 1/4 cup Mag flake with 3/4 cup Epsom.

I used IO and the mag is only 1230. If my math is right, I'll need to add two gallons to raise the mag to the 1350 range in my 800 gallon system that finally has water in it.

[bertoni]

I agree that you're using the correct formula. 1230 ppm is fine, IMO, but 1350 should be okay, too. Assuming the tank has about 500 g of actual water volume, I get about 5-6 gallons to rase the level that much. I'd probably do that in two doses spread over two days, personally, just to be cautious.

[salty joe]

I say 800 gallon system because it took exactly 800 gallons worth of IO to reach 35 on the percent scale on my refractometer.

I took the 47,000 ppt in one gallon and divided by 800 and figured it would raise the mag by about 59 ppt in my system. So two gallons should put me close to 1350 ppt. I think so, anyway.

It's my understanding low mag makes calcium deposits on pumps etc. more likely. Plus it makes sense to me to maintain NSW levels when I can.

Do you see any problem putting the mag flake and Epsom straight into tank rather than mixing with water first? I don't have any creatures yet.

Thanks for confirming the right mag mix to use with a calcium reactor.

[bertoni]

The canonical average magnesium level for the ocean is about 1275 ppm, but 1350 ppm might reduce precipitation a bit. And I should have said 5-6 <b>liters</b> in my previous post. Sigh! So 2 gallons should be close enough, because I was guessing you meant an 800g tank, which would tend to have less than 800g of water.

[salty joe]

I was going by the Salifert mag test. It says NSW mag is between 1300-1500 ppm.

So I'll use a single gallon dose which should take me to just under 1300 ppm. Which is nice because it won't affect salinity as much. Thanks!

[disc1]

Do you see any problem putting the mag flake and Epsom straight into tank rather than mixing with water first? I don't have any creatures yet.


I would dissolve it in water first. It can be hard to get that much magnesium to dissolve in pure water, it might take a lot of shaking and even heating and will probably take a lot of water. Getting it to dissolve from a solid into seawater would be darn near impossible. It would definitely take a very long time.

[salty joe]

Darn, I already threw it in. I guess 'll have to wait it out. I know where the endpoint should be, I'll check in a few days. Would temporarily lowering PH help? PH is 7.96, but I expect it to go up a little as the algae scrubber kicks in.

[disc1]

Would temporarily lowering PH help? PH is 7.96, but I expect it to go up a little as the algae scrubber kicks in.

It might. Do you have any sand and/or rocks in there yet or is it just water? If there's no sand or rocks you can push the pH down below 7 and that should help a little. If you have sand or rock in there then the low pH will also start to dissolve them and that will make keeping the pH low impossible since the action of dissolving the calcium carbonate will tend to push it back up.

[salty joe]

Except for the final 50 lb. of live rock, it's scaped with aragonite and rocks.
What the heck, the mag was not ridiculous, just a little low. I hate to start throwing stuff at it-I'd rather wait it out.
I guess I'll check the mag in a few days, I'll let you guys know how much it moved up.

[bertoni]

Okay, please let us know how it worked out. :)

[salty joe]

Just checked the mag and it looks like 1275. Maybe it's all dissolved or maybe there's a little bit to go. Either way, it looks good.
Thanks you guys for helping me get the tank right!

[bertoni]

You're welcome! Magnesium sulfate and magnesium chloride should be quite in saltwater, so I think the tank will be fine.