Alk question

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Checked my KH yesterday - 6. Added the recommended dose of TM ph/kh triple buffer and got it up to 7. My ph is stable at 8.1. LFS recommended Kent Reef Builder to raise the alk but would keep the ph where it is. I was under the impression if alk was low then the ph would also be. Can anyone explain this?
 
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Ok, no expert in this but this is how I understand it...

The amount Alk is the ability to neutralise acids, if your alk is low then your pH could start swinging, due to the acids building up.

Keep in mind, when dosing Alk supplements, some could affect pH whilst increasing Alk.

I run my tank at about 8dkh and 420ppm Ca.

But hopefully Reef Maniac will post here, he is a GURU at this!
 
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Reef Carbonate™is a concentrated (4,000 meq/L) optimized blend of carbonate and bicarbonate salts designed to restore and maintain alkalinity in the reef aquarium. Calcium and carbonates are essential to all coral growth. If either becomes deficient, coral growth will cease, followed by a rapid decline in coral health. To prevent this you must provide carbonates (Reef Carbonate™) and calcium (Reef Advantage Calcium™ or Reef Complete™).
Used as directed, Reef Carbonate™ will not deplete calcium, magnesium, or strontium which usually tend to precipitate with increasing alkalinity. Reef alkalinity should be maintained at 3–5 meq/L (8–14 dKH). Alkalinity should not be allowed to fall below 2 meq/L.

Sizes: 100 mL, 250 mL, 500 mL, 2 L, 4 L, 20 L

Why It's Different
Whereas competing products simply use sodium bicarbonate, Reef Carbonate™ is made with a blend of carbonate and bicarbonate salts. This blend of salts results in Reef Carbonate™ yielding a pK of roughly 9.0 in saltwater (higher than competing products). In a closed reef system, the multitude of organics produced by reef inhabitants tends to force pH downward, but the advantage of Reef Carbonate’s™ higher pK is a stabilization of pH around 8.3-8.4. Competing products’ formulations make them incapable of such a claim, so pH will always fall below desirable levels for a reef aquarium.
 
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Whereas competing products simply use sodium bicarbonate, Reef Carbonate™ is made with a blend of carbonate and bicarbonate salts.
Advertising talk - For seawater the important buffering system involves carbonic acid (H2CO3), hydrogen bicarbonate (HCO3-), carbonate (CO32-) and hydrogen (H+). There is a balance of the components which depends on the pH and temperature of the water. So, even if you just add carbonate or bicarbonate, the product will react with the other products (ions) in the water to reach the equilibrium ratio for that pH and temperature.

My ph is stable at 8.1. LFS recommended Kent Reef Builder to raise the alk but would keep the ph where it is. I was under the impression if alk was low then the ph would also be. Can anyone explain this?
As stated above, the alkalinity is a "system" with all four (or more) ions in equilibrium - if you change on or two, the other will also change. Don't be fooled by the pH not changing immediately - the chemical reactions take time, and you would only see the end result after some time. If you say that your pH does not change at all I would suspect a faulty pH test. Just the photosynthesis occurring in our tanks alone would cause the pH to change by some 0.2 - 0.4 units between lights on and lights off...

Hennie
 
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Hennie

What's your thoughts on these add-on units for RO units ?

It apparently buffers your RO by pushing the stripped water through another chamber with aragonite.

Will it work ?
 
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Yes, I'm sure it will - have been considering adding something like this as well. Personally, though, I would just add another pre-filter chamber after the RO membrane and fill that with a good calcium reactor media - it would be cheaper in the long run, and you will be sure that you're not adding anything bad back into the water.

Hennie
 

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