Why all the sudden do I have to Buff Alkalinity and nothing else?

Mikelush78 · Nov 7, 2013

Ok so a breif History of me and my tanks...

I had a 90 gallon aquarium for 7 years and last January upgraded to a 180 gallon reef that I built into the wall. (love it) Never once did I have to buff Alk or Cal or anything else. I had only Softies and LPS. I did battle nitrates but found out I had to much sand (Nitrate Trapper and Harvester). Have fixed that with my 180.

Not I move to the 180 gallon tank and obviously add some corals, The Aquarium was fine until last month when my Alkalinity was low when i tested it (5.5 - 5.8ish)

I have to buff with Baking Soda to keep it at 8 and almost every day to every other day.... I am looking to see why I have that issue now?

I now have a Mixed Reef tank with some SPS and Montaporas and such added. I know what everyone is going to ask so here are my parameters:

Alk 5 - 8 (7 - 8 if I am buffing it)
Calcium 420 ppm
Magnisium 1400 - 1420 ppm
Temp 79
Ph 8.0 - 8.3 (depends on how Alkalinity is doing that day)
Salinity 1.024
Nitrates 5 ppm
Phosphate 0
TDS 0

I dont need to buff anything else and everything I read on the internet is if Alk is out of wack then Magnisium is off, or Calcium is way to high... Nether is the case so not sure why this is...

One thing I read that made sense so made the upgrade (made no change on Alk) was that since this tank was in the basement and does not get fresh air.. I took tubing and now I am pulling fresh air from outside for my protein skimmer to help oxygenate the water better.

Well here is my link to my Aquatic Log Web page that has all the info for my tank If you would like to see it:
http://www.aquaticlog.com/aquariums/mikelush78/1

Looking to understand the issue so I can better remedy the situation...

Pic of My tank:

ca1ore · Nov 7, 2013

SPS corals will consume both alkalinity and calcium (and magnesium to a lesser degree) so you should expect to have to add both. No mystery there. If you are adding alkalinity, then I would suggest also adding calcium. The 2-part solutions work pretty well.

Mikelush78 · Nov 7, 2013

Why would I add Calcium if I its not being depleted? Or should I add it when it starts to get depleted?

Irishdolphin · Nov 7, 2013

Tagging along as I have same problem - alk too low and other parameters normal - so very interested to understand probable causes and best solutions

Also question why you would add Alk and Calcium if the issue is that only the alk is too low - thought adding Calcium would actually put downwards pressure on the Alk levels

Mikelush78 · Nov 7, 2013

Agreed with you Irishdolpin... I am thinking of dosing with Kalwasser but its strange the need all of a sudden...

I dont want to have to but if that is my current need based on corals then that is fine.

d2mini · Nov 7, 2013

If you don't add calcium as well, you'll probably end up with an imbalance (too low calcium) eventually and then have to play catch up. I'm going through this now.

downbeach · Nov 7, 2013

The uptake of Ca and Alk, by "œstony" type coral, coralline algae, etc. in a reef system is 20 ppm Ca to 50 ppm(2.8dKH) Alk(CaCO3), which is a ratio of 2 pts Ca to 5 pts Alk (2:5). Equal doses of any two part supplements are designed to provide the same ratio's. So, they will all work but, I have found that the brand name products are going to be more expensive. I use one of the BRS (Randy's) recipes. I considered using the Dow flake, etc., but just can't get my head wrapped around the fact that something that is used in your driveway to melt snow and ice is going to be pure enough to add to an aquarium. So I buy both the Calcium Chloride and Soda Ash from BRS, although I have used A&H Baking Soda as well.

Saturated kalkwasser also contains this same ratio, @ ~ 800 ppm Ca(2pts.) to 2,000 ppm CaCO3(5pts.). It also has the added benefit of utilizing some of the CO2 in your system, which may help keep your pH in line. Even though I'm using a two part recipe, I also still use the kalk in my dosing regimen. The problem with kalk is that it's limited in its ability to keep up with a high demand due to the fact that you're limited to how much you can add to RO/DI water(2tsp.), and your evaporation rate. You can boost that to 3 tsp. with the addition of vinegar, but that also adds a carbon source, and potentially other issues.

If you're using a "reef" grade of salt mix, i.e. Reef Crystals, I'd make sure the salinity is right, by measuring it using a calibrated (@35ppt) refractometer, or metering device. This will ensure you are adding enough Ca, Alk and Mg when you do your WC's. With normal WC's mixed to a salinity of 1.026, I've never had to add Mg, using this type of salt mix.

I think it's possible that you are at a point in your systems uptake of alk and Ca, that your WC's are able to keep up with your Ca and Mg demand, but you need to supplement some alk. There is a lot less Alk in reserve in your system than there is either Ca or Mg, so you will see the changes in your alk much sooner than you will with either Ca or Mg.

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ca1ore · Nov 7, 2013

Mikelush78 said:
Why would I add Calcium if I its not being depleted? Or should I add it when it starts to get depleted?

The 2-part additives are designed to replenish alk and Ca in the ratio they are consumed by corals, so (in theory) dosing one without the other will create an imbalance.

Irishdolphin · Nov 7, 2013

ca1ore said:
The 2-part additives are designed to replenish alk and Ca in the ratio they are consumed by corals, so (in theory) dosing one without the other will create an imbalance.

True, but surely if you already have an imbalance, using a 2-part will just maintain that imbalance. i.e. you need to get into balance first by adding the alk and then once you achieve balance you start 2-part dosing to maintain that balance

MellowReefer · Nov 7, 2013

Are you using seachem reef salt by any chance? I have to dose twice as much alk as cal because their mix is way higher in cal and mag than alk. But I have no sps, only lps.

Mikelush78 · Nov 12, 2013

Reef Crystals

ColtonMeng · Nov 12, 2013

I'd check your test kits. If your kits are expired / older, or just a bad batch, it is possible that your magnesium is lower than normal and dropping your alkalinity out of solution.

Just my $0.02

PS - if this is the case, be careful and go slow when adding more magnesium. it is possible that any insoluble carbonate in the tank can go back into solution once the magnesium is raised, I believe.

Colton

ColtonMeng · Nov 12, 2013

Also, as far as the chemistry of sodium carbonate versus sodium bicarbonate goes, it's important to note that sodium bicarbonate buffers differently than sodium carbonate. While both can be utilized to raise alkalinity levels, I've found it more convenient to use bicarbonate because it will give you levels around 8.3 at 77Â°F when dosing in small quantity. Do keep in mind however that bicarbonate can drop your pH levels initially, then buffer to 8.3. Sodium carbonate will just raise and raise and raise.

See the below- sorry for referencing another forum.

"So what do these things mean to us? When adding sodium BICARBONATE to the system, if there were no other ions, the pH would only be 8.2, not a lot to affect a pH of 8.1 much to start with. If there are significant amounts of organic acids in the water column, they will quickly react with the bicarbonate ion to form the neutral form of that acid and release carbon dioxide gas into the water column. This results in a rapid drop of the pH of the water column due to the formation of carbonic acid and a depletion of the buffer capacity of the solution, not what we might expect when adding baking soda. However, in the presence of adequate amounts of calcium, and the presence of carbonate ions, the pH would be maintained, and bicarbonate is conserved rather than consumed to maintain alkalinity/buffer of the water column. This is why most reef buffer builders contain 8 parts sodium bicarbonate and 1 part sodium carbonate The high pH of the carbonate helps offset the resulting release of carbon dioxide which leads to the formation of carbonic acid in seawater reactions. Sodium Bicarbonate by itself is so slightly alkaline that it fails to turn phenolphthalein indicator red. Sodium Carbonate, on the other hand, turns phenolphthalein dark red due to it's extensive ionization in water. In addition, the carbonate is now available to replenish the bicarbonate ion in the water column, further conserving alkalinity of our seawater.

"If you want to see the chemistry for this, I will be glad to follow up on this for you. The upshot is, Sodium bicarbonate, by itself in most closed systems conditions, will initially drop pH, but usually not below 8.0 or 7.9. Once the existing acids are consumed in seawater, the pH will equilibrate at around 8.2 if you continue to add enough sodium bicarbonate and there are no plants consuming CO2. The idea of having a large reserve of bicarbonate ions is to preserve the pH at or around 8.2 (pH of natural seawater). If you are going to add sodium bicarbonate, it would be best to add a mixture of sodium bicarbonate and sodium carbonate to improve your buffer and pH. I would also recommend mixing the solution with enough water to dissolve the mixture prior to adding it to your water column."

Reference:
http://www.thereeftank.com/forums/f6/sodium-bicarbonate-lowering-ph-why-6931.html

disc1 · Nov 12, 2013

Methinks that the person quoted in the post above has a very limited grasp on chemical equilibria.

You can dose either form of carbonate or bicarbonate. The pH effect will be quite temporary and after things go back to equilibrium you will be in exactly the same place no matter which of the two forms you initially dosed.

ajcanale · Nov 12, 2013

Have you increased your GFO usage? Changing it more often, amount used at once... etc.

ColtonMeng · Nov 13, 2013

disc1 said:
The pH effect will be quite temporary and after things go back to equilibrium you will be in exactly the same place no matter which of the two forms you initially dosed.

well of course

that is why people dose regardless. I was merely commenting that I've found it more helpful to dose bicarbonate than carbonate (or a mixture of the two).

If you have something dropping your pH levels constantly, you're going to have a reduced alkalinity, regardless of what you are dosing. alkalinity is only your tanks ability to withstand pH changes.

Colton

Hodge1995 · Nov 13, 2013

I have been dosing alk for a year and never needed to dose calcium. I use a high calcium salt mix is my only theory why. If you dose both and don't need to you will create an imbalance as well just dose what is needed.

Why all the sudden do I have to Buff Alkalinity and nothing else?

Mikelush78

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