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JSM
10/10/2016, 03:00 PM
My Alk is very high right now, around 14. I mix 100g of saltwater at a time and would like to know the dosage of muratic acid to add to lower it to 8...anyone have any idea? I hate to just start dosing blindly.

Thanks.

Johnseye
10/10/2016, 03:08 PM
As I mentioned in your other post, don't use muratic acid. Use white vinegar. Small amounts 15-30 ml at a time. You don't want to go right from 14 to 8 dkh. Do that over a couple days.

bertoni
10/10/2016, 07:37 PM
Vinegar will lower the alkalinity very temporarily, so I wouldn't dose it for this purpose.

For muriatic acid, adding 1/11,000 of the water volume as muriatic acid will drop alkalinity by 1 meq/l (2.8 dKH). What's your target level? To lower the dKH by 5.6 units, you'd add something like 7 ml.

The pH will drop quite a bit, but aeration will bring it back up. I wouldn't dose muriatic acid into a running system.

Johnseye
10/10/2016, 08:36 PM
Bertoni knows better than me so take his advice. I would still change the cause of the high alk, which is your salt if you're not dosing or running a reactor. I think Bertoni would agree.

Just be careful with muratic acid. They store that stuff outside at Home Depot. Wear good gloves.

bertoni
10/10/2016, 08:46 PM
I agree that changing the salt mix is a good idea. Handling muriatic acid requires care. In addition to gloves, I'd wear goggles. Acid can damage eyes very quickly. The fumes are toxic, too.

blasterman789
10/11/2016, 11:19 AM
Curious why/how Hydrochloric acid lowers alkalinity levels? Er, should I stress 'shorterm'?

Pardon my dusty chemistry which may be bad, but when you add an acid to calcium carbonate it produces a salt of calcium, gas, and carbonate, correct? Your tank contains lots of calcium carbonate in the form of substrate and live rock for that acid to react with. Example: I use vinegar and reactor media with my top off water soaking in a spare gallon jug as calcium / buffer, and if I use too much my alk will get too high.

Otherwise, I've tested many a salt mix with out of the box dKH of >14.

jason2459
10/11/2016, 11:25 AM
This will answer your questions on why short term for vinegar and muriatic acid is not short term beacuse it is not a carbon source for bacteria.
http://reefkeeping.com/issues/2005-03/rhf/

blasterman789
10/11/2016, 11:46 AM
Where does it answer it? Alk / pH / Acidity have a quasi relationship in salt water, but non-linear at best.

I can have a buttload of free hydrogen ions causing low pH, but also have dKH on the high side. Turn the C02 up all the way in your calcium reactor and watch what happens to your tank pH and alk.

Only difference is vinegar forms calcium acetate and not carbonate, correct?

JSM
10/11/2016, 01:25 PM
Not going to dose into a running system, using water change water. I ordered some Aquaforest salt but I don't really want to waste a 100g of new saltwater so I want to bring that down before I use it. Will start with the 7ml and just do a few gallons at a time for my water change so I bring it down slower. Thanks!

jason2459
10/11/2016, 01:28 PM
Not going to dose into a running system, using water change water. I ordered some Aquaforest salt but I don't really want to waste a 100g of new saltwater so I want to bring that down before I use it. Will start with the 7ml and just do a few gallons at a time for my water change so I bring it down slower. Thanks!
Which kind of Aquaforest salt?

The probiotic I got around 7dkh and their reef and sea salts I got around 8dkh on multiple batches.

JSM
10/11/2016, 06:31 PM
Not the probiotic, I'm fine with 8 dkh. Good to know though.

jason2459
10/11/2016, 06:36 PM
Not the probiotic, I'm fine with 8 dkh. Good to know though.
No problem. Just mentioning since 8 dkh saltmix was your goal. With the reefsalt being around that value you would not need to worry about muriatic acid.

bertoni
10/11/2016, 06:48 PM
Curious why/how Hydrochloric acid lowers alkalinity levels?
Hydrochloric acid releases H<sup>+</sup> ions that combine with the carbonate and bicarbonate, lowering the alkalinity permanently. Here's a sample equation:

H<sup>+</sup> + CO<sub>3</sub><sup>--</sup> ==> HCO<sub>3</sub><sup>-</sup>

from

http://www.advancedaquarist.com/2002/2/chemistry

Vinegar releases H<sup>+</sup> ions, as well, but it's an organic acid, and when the acid is consumed, the H<sup>+</sup> is consumed by the hydroxyl released:

CH<sub>3</sub>COO<sup>-</sup> + 2O<sub>2</sub> ==> CO<sub>2</sub> + H<sub>2</sub>O + OH<sup>-</sup>

from

http://reefkeeping.com/issues/2005-01/rhf/index.htm#6


Pardon my dusty chemistry which may be bad, but when you add an acid to calcium carbonate it produces a salt of calcium, gas, and carbonate, correct?
A mineral acid will break the calcium carbonate down into calcium ions, possibly some carbonate or hydroxyl ions, and might release some carbon dioxide, possibly depending on the acid. The carbonate or perhaps hydroxide would add to alkalinity, but the H<sup>+</sup> ions counter-balance that, for a zero net alkalinity change. I don't know how all mineral acids might act in detail, so I can't be more specific. A good chemist could help more.