Alkalinity rising without dosing... possible causes?

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sgrosenb

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@Randy Holmes-Farley I'm reviving this thread with a few questions. You had mentioned that sand is likely the culprit of my increasing alkalinity. And along with it, a rise in calcium. What would you expect Magnesium to do? I ask because I am seeing a trend with my Neptune Trident readings that show a steady, small increase in alkalinity and calcium, but a decline in magnesium. Would this line up with your thought process? If so, would you guess that my system would experience a decline in alkalinity and calcium if I were to remove the sand altogether? I've removed about 75% of it, but I am considering removing it all.

Also - somewhat related but random question - in a FOWLR tank without sand or corals, would you expect to see a decline in alkalinity naturally, or would it just stay level? Just curious.

Thanks as always for your insight.
 
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Dan_P

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@Randy Holmes-Farley I'm reviving this thread with a few questions. You had mentioned that sand is likely the culprit of my increasing alkalinity. And along with it, a rise in calcium. What would you expect Magnesium to do? I ask because I am seeing a trend with my Neptune Trident readings that show a steady, small increase in alkalinity and calcium, but a decline in magnesium. Would this line up with your thought process? If so, would you guess that my system would experience a decline in alkalinity and calcium if I were to remove the sand altogether? I've removed about 75% of it, but I am considering removing it all.

Also - somewhat related but random question - in a FOWLR tank without sand or corals, would you expect to see a decline in alkalinity naturally, or would it just stay level? Just curious.

Thanks as always for your insight.
My fish only system (with sand) alkalinity reliably declines (since setting up in 2014).
 

Randy Holmes-Farley

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@Randy Holmes-Farley I'm reviving this thread with a few questions. You had mentioned that sand is likely the culprit of my increasing alkalinity. And along with it, a rise in calcium. What would you expect Magnesium to do? I ask because I am seeing a trend with my Neptune Trident readings that show a steady, small increase in alkalinity and calcium, but a decline in magnesium. Would this line up with your thought process? If so, would you guess that my system would experience a decline in alkalinity and calcium if I were to remove the sand altogether? I've removed about 75% of it, but I am considering removing it all.

Also - somewhat related but random question - in a FOWLR tank without sand or corals, would you expect to see a decline in alkalinity naturally, or would it just stay level? Just curious.

Thanks as always for your insight.

I can't really see any reason for magnesium to decline in this scenario.

In most tanks alkalinity declines for several reasons:

1. Conversion of ammonia into nitrate that then leaves by water changes (or just continually rises).
2. Many small organisms that folks don't think about use calcium and alkalinity (such as snails, some worms, etc.).
3. Abiotic precipitation of calcium carbonate on heaters, pumps, etc.
 

sgrosenb

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@Randy Holmes-Farley I'm reviving this yet again. Appreciate all of your help. So I've finally gotten to the point where my alkalinity is slowly (well, more quickly lately) declining, which to me is great news. However, I am not seeing a commensurate decline in calcium or magnesium. Over the past few weeks I have been dosing 2-part, but only dosing the alkalinity portion. I have not been dosing anything associated with calcium or magnesium, which have stayed pretty steady throughout that same time.

My understanding is that calcium and alkalinity should drop in tandem. Does it sound odd to you that I am dosing alkalinity, NOT dosing calcium, but seeing no decline in calcium?

As an FYI I dose roughly 25ml into a 165 gallon tank; the 2-part alkalinity solution that says that 1mL of solution with increase alkalinity by 1.7dKH per 1 gallon.

Thanks as always for the help.
 

Randy Holmes-Farley

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How much are you saying alk is declining each day (or is being replace by the alk dosing)?

If alkalinity decline is low, the things that mess with the ratio become significant. Changing nitrate levels, for example, impact alk and not calcium. And water changes can easily maintain calcium and not alk if it is a high calcium mix.

Also, if the decline is small, you may never be able to detect the proportional calcium decline with a kit, since it will be very small.
 
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sgrosenb

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How much are you saying alk is declining each day (or is being replace by the alk dosing)?

If alkalinity decline is low, the things that mess with the ratio become significant. Changing nitrate levels, for example, impact alk and not calcium. And water changes can easily maintain calcium and not alk if it is a high calcium mix.

Also, if the decline is small, you may never be able to detect the proportional calcium decline with a kit, since it will be very small.
Thanks @Randy Holmes-Farley more recently the decline has been more noticeable (at least to me) - roughly 0.25 DKH each day. Is that a small enough amount to a) have other variables throw off the ratio (e.g. Nitrate) and b) no detect due to testing variability? Or is 0.25 dKH / day enough that I should be seeing calcium decline by a meaningful amount over a week or two?
 

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So of this is caused by sand, what would you do if you weren’t able to remove the sand? My ALK has been slowly rising and I can’t figure out why since I don’t dose anything, but I have multiple wrasses that sleep in the sand so I can’t remove it.
many other suggestions? :-/
 

sagedrake690

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To combat rising alk, dose tannic acid. It is dose dependant. The more you sue the faster it will drop and the loger you leave it in the filter the more it will affect the water. It reduces alk.
 

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It turns water yellow to dark brown depending on how much you use and will lower ph slightly and correct alk. To stop the alk drop change the filter. It will all be pulled out with time but you need to change the filter. Making water yellow reduces it by 1-2 a day. Dark brown is 3-5 a day. Slight yellow tint is 1< a day.
 

sgrosenb

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yea that doesn’t seem like a permanent solution or even a short term one that I’d be will to do.
I dont know what to do if you can't take out the source of the alkalinity rise other than using acid (i used Seachem acid buffer for a while in my water change water to lower and maintain alk). I believe @Randy Holmes-Farley mentioned this was the best way to do it. Question for you - do you know what your pH is? I had the same problem as you (rising alkalinity) and solved it by removing my sand. My understanding is that sometimes the pH in the sand can get low enough to break it down and cause alk to rise (I'm no where near a chemist and I could be wrong, but I think that's how it works). So it got me wondering why my sand was breaking down and increasing alkalinity in my tank, but it was so uncommon in other tanks. I later found that my pH was much lower than I had thought due to a faulty probe. Not sure if this explains it, but it might be worth checking. If I'm way off here I'll let the chemists and pros correct me and steer you in a better direction.
 

GlassMunky

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I dont know what to do if you can't take out the source of the alkalinity rise other than using acid (i used Seachem acid buffer for a while in my water change water to lower and maintain alk). I believe @Randy Holmes-Farley mentioned this was the best way to do it. Question for you - do you know what your pH is? I had the same problem as you (rising alkalinity) and solved it by removing my sand. My understanding is that sometimes the pH in the sand can get low enough to break it down and cause alk to rise (I'm no where near a chemist and I could be wrong, but I think that's how it works). So it got me wondering why my sand was breaking down and increasing alkalinity in my tank, but it was so uncommon in other tanks. I later found that my pH was much lower than I had thought due to a faulty probe. Not sure if this explains it, but it might be worth checking. If I'm way off here I'll let the chemists and pros correct me and steer you in a better direction.
Tank PH is between 8.0 and 8.3 daily swing.
 

GlassMunky

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I dont know what to do if you can't take out the source of the alkalinity rise other than using acid (i used Seachem acid buffer for a while in my water change water to lower and maintain alk). I believe @Randy Holmes-Farley mentioned this was the best way to do it. Question for you - do you know what your pH is? I had the same problem as you (rising alkalinity) and solved it by removing my sand. My understanding is that sometimes the pH in the sand can get low enough to break it down and cause alk to rise (I'm no where near a chemist and I could be wrong, but I think that's how it works). So it got me wondering why my sand was breaking down and increasing alkalinity in my tank, but it was so uncommon in other tanks. I later found that my pH was much lower than I had thought due to a faulty probe. Not sure if this explains it, but it might be worth checking. If I'm way off here I'll let the chemists and pros correct me and steer you in a better direction.
Also doing water changes with artificially lowered ALK doesn’t seem like a great solution either as if then have to do almost constant changes just to keep things from going up, which is expensive and a waste of salt.
 

sagedrake690

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I've had crustaceans survive this process. An emerald crab and a mantis shrimp. it does make sense though if you have anaerobic conditions it will over time turn sand into its base components by becoming acidic. Under the right conditions even the rocks can release minerals. The tannic acid DOES remove the source of the alkalinity and it binds to the acid and gets trapped in the filter. That's why your filter gets shot after dosing tannins. I need to dose baking soda to my FW tannin river tank because it gets so soft over time. I would find a way to stir up that sand. Large nessarius snails and sand stars do great for aeration.
 

GlassMunky

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I've had crustaceans survive this process. An emerald crab and a mantis shrimp. it does make sense though if you have anaerobic conditions it will over time turn sand into its base components by becoming acidic. Under the right conditions even the rocks can release minerals. The tannic acid DOES remove the source of the alkalinity and it binds to the acid and gets trapped in the filter. That's why your filter gets shot after dosing tannins. I need to dose baking soda to my FW tannin river tank because it gets so soft over time. I would find a way to stir up that sand. Large nessarius snails and sand stars do great for aeration.
The tank has nasarius snails, a sand sifting startfish and a leopard wrasse that digs and sleeps in the sand. I would think this would keep it aerated, but maybe not.

Other than manually turning all the sand over myself I’m not really sure what could be done if that’s the thing.
 
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GlassMunky

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The tank has nasarius snails, a sand sifting startfish and a leopard wrasse that digs and sleeps in the sand. I would think this would keep it aerated, but maybe not.

Other than manually turning all the sand over myself I’m not really sure what could be done if that’s the thing.
The rocks themselves also sit directly on the glass and there’s caves that the fish can enter on one side of the tank and exit on the other. So there’s nothing under them to crest an anaerobic spot there either.
 

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The tank has nasarius snails, a sand sifting startfish and a leopard wrasse that digs and sleeps in the sand. I would think this would keep it aerated, but maybe not.

Other than manually turning all the sand over myself I’m not really sure what could be done if that’s the thing.
And in nature there always will be this release of minerals. This is how the ocean maintains nutrients. Breakdown of solid minerals in acidic anaerobic conditions is natural. Just make sure you have plenty of plants to combat it. The hydrogen sulfide smells like sewage or rotten eggs. This is usually an inch down in the sand flats. Just dig on the beach and the dirt underneath is acidic and stinky. If the alk is going up then acids are destroying the shell and calcium particles in the sand making them water soluble. A lot of sand and shell contains calcium and sodium bicarbonate. In the water the tannins will attract the bicarbonate and bind it to the carbon in the filter. Thats why 1/4 tsp in a 50 gal will turn a pillows of filter media into brown goo.
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So my refugium has this weird design that makes it a filter too. I made water tight pieces from insulation foam and the filter is rolled polyester spider webbing. It stretches nice and you sprinkle carbon on it and roll it up. Thats a new filter. That old one is 2 days after a tannin dosing. I got my alk to 13 now! Dropped 3 in 2 days. Got a mantis shrimp in there. It was given to me by a shop owner. It was a hitchhiker and a chiragra mantis so he just told me to please take it. Its survived 2 dosings. It actually has been quite active since I dosed. It didn't like the high alk but I had nowhere for it. The shop owner said he was gonna feed it to something if I didnt take it. Hes still kickkin!
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sagedrake690

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tannins go to about 6 in on. In water they make it

However, the tannins, which are the substances which "tint" the water, cannot "overcome" the calcium and magnesium ions, and drive down the pH significantly in water with high levels of these ions present. It simply is putting more materials into the water (which are often detectible by TDS meters in aquariums).
 

GlassMunky

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Yes none of this really helpful.
I’m not dosing my tank full of tannins and turning it into a black water tank. That’s silly.
that’s not how reef tanks run
 

Randy Holmes-Farley

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To combat rising alk, dose tannic acid. It is dose dependant. The more you sue the faster it will drop and the loger you leave it in the filter the more it will affect the water. It reduces alk.

Seems an odd solution that I would not recommend as there are far simpler and cleaner methods. Tannic acid will bind trace metals and impact bioavailability, will potentially yellow the water, and may ultimately be metabolized, releasing some or all of the alkalinity back.

If one really wants to lower alkalinity in a running reef tank without doign water changes with a low alk mix, one way is to do them with a super low alk mix that you make yourself, or by very, very slowly adding a mineral acid to the tank. Sodium bisulfate (like Seachem acid buffer) or hydrochloric acid will permenently lower the alk and do little else besides lower pH when first added (which tannic acid will also lower pH to the same degree per unit of alk depleted).
 
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