Alkalinity rising?

[JonasRoman]

Ok... back to square one then! lol

I'm going to try another bottle of reagent but I wouldn't expect an issue with the reagent to gradually give a higher reading each day. Could the algae die-off be providing something that could influence this?

I do not think algue could be the cause. When algue growe they consume CO2 and that Will not affect alk. Some algue consume HCO3 but also there it is not an effect on alk as to consume one HCO3 it is also consume one H.
Opposite, when algue die it releases organic carbon as the algue have fixed the inorganic carbon to organic in the photosyntes. Thus organic carbon is released in some way and that could maybe by bacteria be reoxidized to CO2 and again, CO2 Will not affect alk.

 

[griff500]

I agree with Randy that a plausable explanation is increase in denitrifikation. When you have equa denitrifikation as nitrification it is still an decrease in Alk as it is produced 4 H to oxidice one ammonium molecule and only gets 2 OH to reduce same molar/amount nitrate. Thus, it must be att least twice so much denitrifikstion compared to nitrification to get a nettoincrease in alkalinity. As you dose organic carbon i think yoy maybe have an explanation here. In that case it Will stabilize itself because when nitrate go down the reduction of that will decrease over time and the balance between nitrification and denitrifikation Will be back and Alk be more stable.
Randy have to correct me if i am wrong on the exact stochiometri.

Concerning Hanna I believe there method is not sensitive to pH. The reason is (i believe) is that they adding a constant amount acid of that amount so the sample always go below the eqvivalentpoint for HCO3, thus a bit under pH 4.2. Then in that case the pH beyond this slope is not any more sensitive to CO2 as 100% of all carbonates is pushed to H2CO3 and CO2(aq) and as long as the pH is below 4.2 there will be no dissociation at all of H from H2CO3.
So, the point we Will reach on the curve beyond /below 4.2 is only dependent on the alkalinity in the water before we added the constant amount of acid.
I have tried this method of myself and experimentet with different acids and concentrations and it is working.
I tried measure same water with different CO2 levels and got down to excactly the same pH point with same alk. So, i think you can trust Hanna method. There is only one weakness: if the alk is so high so the amount of acid is not enough to reach a point below 4.2. But i guess Hanna has calculated at least that the metre will manage alk from dKH 14 and down maybe.
They by the way use bromocresolgreen with acid added. The light from the diod is 610 nm as the difference in asorbance between the different colorchange for bromocresolgreen in this wavelenght is maximal.

Thanks for that. I'll continue to keep an eye on it and hopefully i will settle soon.

 

[Perry]

any update?
I am also dealing with an increase in alk without dosing. I have used lamotte and salifert to validate that I increase daily in alk. I also have tested RODI, and zero alk. The common denominator is that I have about 15lbs of real reef rock. I mix the saltwater for change at 6.8dkh, and within a week, my alk goes up, one would consider that the 20 sps corals should be taking in alk, but yet I increase every day. I am going to pull all the rock tomorrow, do a water change, and see if I can get my numbers down.

 

[Randy Holmes-Farley]

These are the things that can lead to apparent alkallinty rises:

Test error,
top off with tap water,
decline in nitrate,
dosing of nitrate,
dissolution of new artificial live rock
supplements or foods that contain alkalinity even if you do not realize it
dissolution of live rock or sand due to very low tank water pH
dissolution of live rock or sand due to very low pH inside of them due to degradation of organics

 

[chipmunkofdoom2]

@Dana Riddle stated in his 2016 MACNA talk that if insufficient CO2 is present, carbonate can be consumed by the photosynthesis process. This was mentioned in the context of the zooxanthellae in corals, but I suppose that GHA could do this as well. I would think this is unlikely however. Your home likely has higher CO2 levels than natural reefs, so I would think that CO2 would not be so limited that the hair algae would need to consume carbonate to complete photosynthesis.

 

[Randy Holmes-Farley]

@Dana Riddle stated in his 2016 MACNA talk that if insufficient CO2 is present, carbonate can be consumed by the photosynthesis process. This was mentioned in the context of the zooxanthellae in corals, but I suppose that GHA could do this as well. I would think this is unlikely however. Your home likely has higher CO2 levels than natural reefs, so I would think that CO2 would not be so limited that the hair algae would need to consume carbonate to complete photosynthesis.

You partly misunderstood. When bicarbonate or carbonate are used for photosynthesis (and it often is), only the CO2 is consumed (the alkalinity cannot be consumed by photosynthesis). The result is release of OH-, which combines with more CO2 to reform carbonate or bicarbonate. So there is no change in alkalinity. It's just a more ready source of available CO2.

 

[venomcc]

Reviving this thread from the dead, but i experienced the exact same situation as the OP with regards to significant GHA die off and a steady increase in alkalinity. I've been observing the alkalinity using the Trident. I had found no explanation anywhere until I ran into this thread, at least I know I'm not the only one, even if there's still no answer.

 

[rmurken]

Reviving this thread from the dead, but i experienced the exact same situation as the OP with regards to significant GHA die off and a steady increase in alkalinity. I've been observing the alkalinity using the Trident. I had found no explanation anywhere until I ran into this thread, at least I know I'm not the only one, even if there's still no answer.

I just found this post as well and am going to start a new thread. I have a phenomenon I wanted to check with folks that involves an upward Alk drift I can’t explain.

 

[Randy Holmes-Farley]

Reviving this thread from the dead, but i experienced the exact same situation as the OP with regards to significant GHA die off and a steady increase in alkalinity. I've been observing the alkalinity using the Trident. I had found no explanation anywhere until I ran into this thread, at least I know I'm not the only one, even if there's still no answer.

Maybe the dead algae is releasing compounds that deter calcification by corals (e.g. phosphate).

 

[sgrosenb]

I'm reviving this thread (again) - I still can't figure out why my alkalinity rises, but it certainly does. Here's my post on this subject - still haven't found the culprit but according to @Randy Holmes-Farley it could be the sand releasing it due to "degradation of organics" (admittedly I don't know what that is - if anyone has an explanation I'd be interested to understand) https://www.reef2reef.com/threads/a...ive-tried-everything-help-appreciated.645769/

 

[Cory]

What alkalinity test are you using? How are you doing the test?

 

[sgrosenb]

I have a GHL KH director and a LaMotte Alk test. both are always within 0.2 dKH of each other so I'm fairly confident its accurate

 

[eshtog]

I’m baffled as well as I am experiencing the same unexplained and frustrating alkalinity rise. I did a water change last Wednesday and my alkalinity dropped down to 9.14. Now not even a week later it has crept up to 9.64 I don’t know what to do. Calcium and magnesium have been stable.

 

[sgrosenb]

I’m baffled as well as I am experiencing the same unexplained and frustrating alkalinity rise. I did a water change last Wednesday and my alkalinity dropped down to 9.14. Now not even a week later it has crept up to 9.64 I don’t know what to do. Calcium and magnesium have been stable.

@eshtog what do you have for sand and rock? did you use 100% dead rock?

 

[eshtog]

@eshtog what do you have for sand and rock? did you use 100% dead rock?

Yes I started with dead rock over 2 years ago and sand is Caribsea special grade.

 

[sgrosenb]

Yes I started with dead rock over 2 years ago and sand is Caribsea special grade.

I seem to be seeing a pattern that people who start with 100% dead rock and sand are having alk rising problems and also trouble growing SPS. did you add any live rock or other natural (not bottled) bacteria sources into the tank since inception? can you grow SPS?

I've had my tank up for 18 months, started with dead rock and similar type sand. I cant grow SPS despite all my levels being perfect. I'm on order for some live rock from Tampa Bay Saltwater that I'm hoping will turn the tide...

 

[eshtog]

I seem to be seeing a pattern that people who start with 100% dead rock and sand are having alk rising problems and also trouble growing SPS. did you add any live rock or other natural (not bottled) bacteria sources into the tank since inception? can you grow SPS?

I've had my tank up for 18 months, started with dead rock and similar type sand. I cant grow SPS despite all my levels being perfect. I'm on order for some live rock from Tampa Bay Saltwater that I'm hoping will turn the tide...

It’s interesting the rock is the only thing left that I suspect could be the problem as well. The only sps I have left is my Walt Disney. LPS are no problem and thrive in my tank.

I think I’m going to give Tampa Bay live rock a shot. Are you planning on replacing your live rock or just adding to your existing rock?

 

[sgrosenb]

It’s interesting the rock is the only thing left that I suspect could be the problem as well. The only sps I have left is my Walt Disney. LPS are no problem and thrive in my tank.

I think I’m going to give Tampa Bay live rock a shot. Are you planning on replacing your live rock or just adding to your existing rock?

Cool. I think that's the missing key ingredient. I cant explain the rising alk, but the similarities in all the tanks that have rising alk is tough to ignore (100% dead rock, aragonite sand). I'm just adding to the rock I already have. hoping to get some good bacteria, sponges, worms, etc etc. Only downside to TBS rock is unwanted critters but I think those can be caught with a water bottle trap before it even goes in the tank. How is your coraline algae?

 

[eshtog]

Cool. I think that's the missing key ingredient. I cant explain the rising alk, but the similarities in all the tanks that have rising alk is tough to ignore (100% dead rock, aragonite sand). I'm just adding to the rock I already have. hoping to get some good bacteria, sponges, worms, etc etc. Only downside to TBS rock is unwanted critters but I think those can be caught with a water bottle trap before it even goes in the tank. How is your coraline algae?

Coraline seems to be ok, but I definitely had more when I used live rock in my 90 gallon. When I was using NoPox I definitely had a reduction.

 

[eshtog]

Frustrating You can see the drop right after the water change and then it starts going up again!