New to the Hobby, can't get Alk down.....

[Chukwagin]

Hi everyone, I'm very new to this, pulling my hair out here. I have a 16 g tank,

PH 8.2
Calcium 440
Salinity 1.025
Ammonia, Nitrates, Phospates 0
Alkalinity 14-15
Magnesium - just ordered test, have no idea.

I've had this problem for about two weeks or more. LFS recommended adding Vitamin C to lower Alkalinity, I have done two water changes in last two weeks. Alkalinity goes down to 12-13 and then right back up to 14-15 the next day. My corals are happy and growing, but I don't like my Alkalinity so high, what can I do to get it down? I change my water almost every 17 days, and recently once a week the last two weeks trying to get it down to normal levels. LFS recently recommended dosing Magnesium, they didn't have a test kit on hand. Help.....

 

[Reefing Madness]

Ok, you can change salts to Instant Ocean, as it mixes out low in the elements.
But in the meantime you can lower it using Muriatic Acid, if its bothering you that much.
ALK can be lowered using Muriatic Acid and a medicinal syringe.
High alkalinity
The "acidity" (that being essentially negative alkalinity) of muriatic acid straight from the bottle is about 11,000 meq/L.

So adding 1/11,000 of the water volume as this acid will drop alkalinity by 1 meq/l (2.8 dKH).

You want a drop of 13-7 = 6 dKH, or 2.1 times that amount, so you'd add 1/5,100th of the water volume.

13 gallons ~ 49 L

1/5100 of 49 L = 9.6 mL

So I'd add 5 ml and stir well for a few minutes and see what alkalinity you get. Then dose again assuming it seems on the right track.

You'll need to aerate well after adding the acid to blow off the excess CO2 and bring up the pH.
Quote taken from Randal Holmes-Farley

 

[Chukwagin]

Ok, you can change salts to Instant Ocean, as it mixes out low in the elements.
But in the meantime you can lower it using Muriatic Acid, if its bothering you that much.
ALK can be lowered using Muriatic Acid and a medicinal syringe.
High alkalinity
The "acidity" (that being essentially negative alkalinity) of muriatic acid straight from the bottle is about 11,000 meq/L.

So adding 1/11,000 of the water volume as this acid will drop alkalinity by 1 meq/l (2.8 dKH).

You want a drop of 13-7 = 6 dKH, or 2.1 times that amount, so you'd add 1/5,100th of the water volume.

13 gallons ~ 49 L

1/5100 of 49 L = 9.6 mL

So I'd add 5 ml and stir well for a few minutes and see what alkalinity you get. Then dose again assuming it seems on the right track.

You'll need to aerate well after adding the acid to blow off the excess CO2 and bring up the pH.
Quote taken from Randal Holmes-Farley

Thanks for the reply! I will try that