Alk raising/lowering itself???

[Silverking90]

230gal mixed reef tank. 8 months old, refugium, skimmer, carbon and gfo reactors.

Months ago I started dosing alk. I did one manual dose to get it to 7.7. on April 13th. April 20th, alk was 10.5, April 22nd at 7.7 again. On april 30th back up to 9.1, and by May 10th, it was at 9.8. Today it is at 8.5. Just over here scratching my head as to why this is swinging all around??? NOTHING goes into my tank other than Vibrant once a week and im not doing any water changes.

I started dosing Platinum Corals color enhancer supplement during the first swing in alk, so naturally I assumed it was that product and stopped dosing it. Sure enough it did retreat back to 7.7 after stopping, but 8 days later it went up again to 9.1. Platinum corals claimed their product has no alk boosters in it and didnt think their product was responsible for the alk swing.
Thanks in advance!

 

[vegamedic]

Is your salinity staying put? I assume you have an ATO with a tank that size.

First thing that pops to mind is test kit error. What are you using to test and how old are your reagents?

 

[madweazl]

If you aren't dosing and you aren't doing water changes, how are you maintaining any levels?

 

[recess62]

What are your other tank parameters? In my system if there are big shifts in Nitrate there will be big swings in my Alk in the opposite direction

 

[Randy Holmes-Farley Verified Community Expert]

Might just be testing error.

What are you replacing evaporated water with?

What type of rock in the tank (artificial rock that isn't fully cured can raise pH and alkalinity).

If nitrate levels are changing up and down, that would alter alkalinity. Rising nitrate by 50 ppm would drop alk by 4.5 dKH, and lowering them by the same amount (through consumption by organisms) raises it back by the same amount).

Some foods may contain some alkalinity if it contains some things like buffered vitamin C.

Finally, rock and sand may slowly dissolve deep in pores and such where the ph may be quite low due to degradation of organics to CO2, and that can boost alkalinity.

 

[Randy Holmes-Farley Verified Community Expert]

I started dosing Platinum Corals color enhancer supplement during the first swing in alk, so naturally I assumed it was that product and stopped dosing it. Sure enough it did retreat back to 7.7 after stopping, but 8 days later it went up again to 9.1. Platinum corals claimed their product has no alk boosters in it and didnt think their product was responsible for the alk swing.

Perhaps they do not understand what happens to their product after dosing. I don't know if it is enough to cause your issues, but many of the things they list could boost alkalinity if delivered in certain forms.

For example, if the fatty acids are present as sodium salts, they would boost alkalinity. The same is also potentially true for certain amino acids (aspartic acid, glutamic acid), the carbohydrates, the humic and fulvic acids, and the vitamins. If they go in as sodium salts and get metabolized to CO2, they will boost alkalinity. (and, if they go in as acids and do not get metabolized, they will deplete alkalinity).

http://www.coral-shop.com/news.php?id=166

24 minor and trace elements
(B, Ba, Be, Br, Cd, Co, Cr, Cu, F, Fe, I, Ir, Mn, Mo, Ni, Rb, Re, Ru, Se, Sr, Ti, V, W, Zn)
6 noble metals
3 marine vitamins
8 marine carbohydrates
21 amino-acids and their derivatives
2 mixtures of humic and fulvic acids (complex acids)
10 fatty acids

 

[dwolson]

There PH changes at night which I’m told changes alk. Are you testing at different times, Day/night?

 

[Randy Holmes-Farley Verified Community Expert]

There PH changes at night which I’m told changes alk. Are you testing at different times, Day/night?

pH swings up and down day to night, but alk does not cycle up and down unless you are dosing in ways that cause it to do so.

 

[Silverking90]

Is your salinity staying put? I assume you have an ATO with a tank that size.

First thing that pops to mind is test kit error. What are you using to test and how old are your reagents?

Yes i have an ATO and im keeping it slightly above 1.025. I use red sea test kits and the kit is about 6 months old so I just assume the reagents are good.
I will say though, this morning I test the water again, and now im seeing an alk level of 6.5. At this point Im going to say I have bad judgement with reading the test kits cuz a swing from 8 to 6 in under 24hrs would have killed everything, and everything is fine sooo..

 

[Randy Holmes-Farley Verified Community Expert]

Yes i have an ATO and im keeping it slightly above 1.025. I use red sea test kits and the kit is about 6 months old so I just assume the reagents are good.
I will say though, this morning I test the water again, and now im seeing an alk level of 6.5. At this point Im going to say I have bad judgement with reading the test kits cuz a swing from 8 to 6 in under 24hrs would have killed everything, and everything is fine sooo..

You may have test issues, but many tanks will lost 2 dKH in a day.

 

[Silverking90]

Might just be testing error.

What are you replacing evaporated water with?

What type of rock in the tank (artificial rock that isn't fully cured can raise pH and alkalinity).

If nitrate levels are changing up and down, that would alter alkalinity. Rising nitrate by 50 ppm would drop alk by 4.5 dKH, and lowering them by the same amount (through consumption by organisms) raises it back by the same amount).

Some foods may contain some alkalinity if it contains some things like buffered vitamin C.

Finally, rock and sand may slowly dissolve deep in pores and such where the ph may be quite low due to degradation of organics to CO2, and that can boost alkalinity.

My rocks came from the local beach after Irma, that storm uncovered a ton of rocks that were free of any growth at the time.
My other levels are always different every time i test. Stability isnt a thing in my tank, and really never has been. Everything seems to swing lightly to moderately, but i only usually test once a week or so. Since yesterday i began testing daily to try to understand all this better. Nitrates have been consistently under 10 for a few months. Today they are at 10, and I assume thats because I stopped dosing vibrant 2 weeks ago. My nitrates have never seen 50 so, given what you said, Im not sure my nitrates are varying enough to cause my swings.