How to LOWER Alk in freshly mixed water

[Origami]

here's another question-

what happens when you put the high alk water into the tank? does it spike the alk as I would think, but then settles back to the norm?

If so, it's not something that I would worry about as it will keep the ALK stable. This way you don't have to dose ALK to bring it up.

Have you been recording your test results weekly and then see what happens to ALK after w/c?

If it's too high, then your test results would show a gradual rise in ALK if not being consumed, but if ALK demand is moderate or high, then your results might show a flatline of ALK.

 

I would do this before dosing acid to lower the pH and ALK.

If you add high alk water to the tank, depending upon the amount that you add and the CO₂ level in the tank, alk will rise. If both the tank and the change water are in CO₂ equilibrium with the air, then alk will rise. If there is an excess of CO2 in the tank, then alk will settle somewhat lower.

 

Alkalinity is the capacity of a solution to neutralize an acid. It is the complement of pH (aka pOH). It does  not "settle back to the norm" no more than an acid settles to being a non-acid if left untouched. However, it can be consumed by CO₂ in the water (which associates with water to form carbonic acid). That's why you want to aerate the newly mixed water with ambient air initially - to bring the dissolved gasses in the solution to equilibrium. Here's how alkalinity interacts with CO₂ to create the two major ions associated with "carbonate alkalinity" (term used generally to reflect both bicarbonate and carbonate ions):

 

OH^- + CO₂ ==>> HCO₃^-  (bicarbonate alkalinity)

OH^- + HCO₃^- ++>> CO₃^-- + H₂0 (carbonate alkalinity)

 

So, you see, alkalinity comes from the OH- (hydroxide) ion interacting with CO₂. And, it can be neutralized by the H⁺ (hydrogen or hydronium - sometimes shown as H₃0+)) ion characteristic of an acid to produce water.

 

When you add an acid (with free H⁺ions), this is what happens:

 

CO₃^-- + H⁺ ==>> HCO₃^- (carbonate is oxidized to bicarbonate)

HCO₃^- + H⁺ ==>> H₂0 + CO₂ (bicarbonate is oxidized to CO₂ and water. Thus the pH depression and the need to "blow off" the extra CO₂)

 

If Mike does not want to run at a higher alk level and the salt is too high in alk, then either he would have to make smaller water changes (to minimize the alk rise and to allow consumption to remove the extra alk), neutralize the excess alkalinity, change his specific gravity, or change salts.

 

Dosing an acid to lower alkalinity is analogous to dosing a base (carbonate, bicarbonate, or even hydroxide) to raise alkalinity.

[BowieReefer84]

Ok, since the Alk was 11 and the Calc was only 380 in the freshly mixed Instant Ocean I have done the following:

 

1- Added 6ml of the diluted MA (9:1)

2- Added 7.5ml of the Bionic Calc portion of the two part.

 

This should bring me closer to my goal range of 420 Calc and 8.6 Alk.  I am going to let it mix for a while and perform some more tests.  If I can find how much of each to add when doing a 3gal water change it will be very easy to conduct water changes with same parameters as the tank.

 

If it doesn't work or seems like too much trouble I will likely switch salt mixes as a few folks have recommended already.

[BowieReefer84]

Ok, so I ended up adding 8.25ml of the 9:1 MA solution (Thanks Tom for the math/chem numbers you provided), and 11.5ml of the Calc portion of B-Ionic two part to 3 gal of IO mixed to 1.026.

 

Starting test numbers:  11alk and 380calc

 

CURRENT test numbers:  8.6alk and 420 calc

 

I am very happy with the results, and will make it a point to continue adding these two solutions to freshly mixed water.

 

I will test again in 24 hours to see if anything changes before doing the water change.

[Origami]

Ok, so I ended up adding 8.25ml of the 9:1 MA solution (Thanks Tom for the math/chem numbers you provided), and 11.5ml of the Calc portion of B-Ionic two part to 3 gal of IO mixed to 1.026.

 

Starting test numbers: 11alk and 380calc

 

CURRENT test numbers: 8.6alk and 420 calc

 

I am very happy with the results, and will make it a point to continue adding these two solutions to freshly mixed water.

 

I will test again in 24 hours to see if anything changes before doing the water change.

Cool! It worked.

 

 

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[smallreef]

Awesome! Glad to know if ever I need to touch mine...

[lnevo]

Whats the ph at now?

[BowieReefer84]

Whats the ph at now?

I will test that tonight and let you know.  It prob went down early on, but should rise back up with good aeration.

[BowieReefer84]

Whats the ph at now?

PH was at 8.0 in mixing container.  Tank is running at like 8.2-8.3.  I have a C02 scrubber hooked to skimmer intake to boost PH.  The tank is in a sealed off basement.

 

Water change now done.

[BowieReefer84]

Tom,  the quote:

 

"When dripping vinegar it is best to not dilute it too much or store the diluted vinegar too long since diluted vinegar can be broken down by bacteria in the dispensing vessel reducing the amount of carbon dosed. Dilution and delivery the same day is fine, but a 10% vinegar plus 90% water solution is not likely stable over the course of a week or two."

 

taken from http://reefkeeping.com/joomla/index.php/current-issue/article/116-vinegar-dosing-methodology-for-the-marine-aquarium

 

Leads me to believe the stored solution of MA with water won't hold up.  My most recent waterchange proved this.  It took a decent amount more MA solution to lower the Alk to 8.0.  So, from now on I am just going to use a little less than 1ml straight MA instead of 8ml of the solution I mixed up.

[Origami]

Tom,  the quote:

 

"When dripping vinegar it is best to not dilute it too much or store the diluted vinegar too long since diluted vinegar can be broken down by bacteria in the dispensing vessel reducing the amount of carbon dosed. Dilution and delivery the same day is fine, but a 10% vinegar plus 90% water solution is not likely stable over the course of a week or two."

 

taken from http://reefkeeping.com/joomla/index.php/current-issue/article/116-vinegar-dosing-methodology-for-the-marine-aquarium

 

Leads me to believe the stored solution of MA with water won't hold up.  My most recent waterchange proved this.  It took a decent amount more MA solution to lower the Alk to 8.0.  So, from now on I am just going to use a little less than 1ml straight MA instead of 8ml of the solution I mixed up.

Not at all. The acetate ion (HCOOH-)  is bio-available and is consumed by bacteria as a cabon source. (I know, I had a slimy top off container at one point when dosing vinegar this way.)

 

Muriatic acid is also known as hydrochloric acid. It strongly dissociates into a hydrogen (or hydronium) ion and a chloride ion. Neither are "bacteria food."

 

Remember, over 60% of your "raw" muriatic acid is still water. All you've done in diluting it is to add more of the same. It's acidity should hold up just fine if stored properly.

[Origami]

Mike, did you allow your saltwater to stabilize (aerate) before attempting adjustments?

 

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[BowieReefer84]

Mike, did you allow your saltwater to stabilize (aerate) before attempting adjustments?

 

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Yes, for about 24 hours.  I haven't tossed that mix yet.  I will use it again next weekend and see how many ml it takes, and report back.  I swear it seemed like I added about 12ml this time instead of 8ml like last time to reach the same end result.

[wangspeed]

What percent of water are you changing out?  I doubt it's worth to trouble of bringing the alk back down.  Just use it in 10% WC, and reduce dosing til you're out of this salt.  There is nothing wrong with 7.6 alk either.  That's closer to NSW, and is appropriate for a low nutrient tank.

 

I know you've already done it, but I would not use MA to bring alk down.  You are starting to play with fire.

 

In the long run, you should switch to a salt that mixes up like NSW.  Red Sea blue bucket, Seachem Reef Salt, etc, and rely on dosing to stabilize.

[BowieReefer84]

What percent of water are you changing out?  I doubt it's worth to trouble of bringing the alk back down.  Just use it in 10% WC, and reduce dosing til you're out of this salt.  There is nothing wrong with 7.6 alk either.  That's closer to NSW, and is appropriate for a low nutrient tank.

 

I know you've already done it, but I would not use MA to bring alk down.  You are starting to play with fire.

 

In the long run, you should switch to a salt that mixes up like NSW.  Red Sea blue bucket, Seachem Reef Salt, etc, and rely on dosing to stabilize.

Yea, switching salts would be easier.  I hear good things about both salts you mentioned as well.  The thing was I didn't realize Instant Ocean mixed to such a high Alk.  I'm doing 15% a week.  What salt do you use?  I see in your sig you run a zeo tank.

[wangspeed]

Yea, switching salts would be easier. I hear good things about both salts you mentioned as well. The thing was I didn't realize Instant Ocean mixed to such a high Alk. I'm doing 15% a week. What salt do you use? I see in your sig you run a zeo tank.

I run the Red Sea blue bucket. Usually a special order around here but the price is reasonable. The seachem can be had on Amazon for even less but you'll need to offset the alk reading on it since there is so much borate. IIRC it throws the reading off by +1. Double check that if you go SCRS though. I really like that both companies are transparent about what they contain and the specs they should mix to.

 

I wouldn't sweat 15% WC with higher alk. You shouldn't budge the overall alk very much.

 

 

--

Warren