Alk at 15 without dosing any

[Drone]

I have a 2 year old 13.5 gallon with acans and hammers (all currently doing well) with no major issues. I do about 10-20% WC every week but I’ve been getting insane alkalinity numbers. I dose calcium and mag (currently at 440 and 1300) but I have never dosed alk because it’s always super high. I figured it could be my test kit but I took some water in to my LFS and they got the same reading I did. I’ve done two larger water changes the past weeks but I tested again today and it’s still sitting at 15. Any ideas as to what the is going on?

Thanks

 

[ReefingDreams]

What is the alkalinity of your water change water?

 

[Drone]

What is the alkalinity of your water change water?

Always 8-9

 

[ReefingDreams]

Have you actually checked it in the cases you've done a water change and haven't seen a drop? What salt are you using? As a side note, a 10% water change isn't going to drop much for you if your freshly mixed saltwater is 9dkh.

 

[Drone]

Have you actually checked it in the cases you've done a water change and haven't seen a drop? What salt are you using? As a side note, a 10% water change isn't going to drop much for you if your freshly mixed saltwater is 9dkh.

I did a 30% two days ago and checked it today and read 15. And to reiterate I’ve never added a drop of alk/kalk or anything to this tank. I get synthetic from my LFS and they use fritz reef pro mix.

 

[gbroadbridge]

I have a 2 year old 13.5 gallon with acans and hammers (all currently doing well) with no major issues. I do about 10-20% WC every week but I’ve been getting insane alkalinity numbers. I dose calcium and mag (currently at 440 and 1300) but I have never dosed alk because it’s always super high. I figured it could be my test kit but I took some water in to my LFS and they got the same reading I did. I’ve done two larger water changes the past weeks but I tested again today and it’s still sitting at 15. Any ideas as to what the is going on?

Thanks

Are you dosing anything else? What are you dosing for Calcium and Magnesium?

Do you know your Nitrate levels?

 

[Drone]

Are you dosing anything else? What are you dosing for Calcium and Magnesium?

Do you know your Nitrate levels?

Nitrates around 10ppm, I’ve only ever dosed Red Sea calcium and magnesium. Only other thing that has ever been in the tank is reef roids

 

[gbroadbridge]

Nitrates around 10ppm, I’ve only ever dosed Red Sea calcium and magnesium. Only other thing that has ever been in the tank is reef roids

The reason I asked is because bacterial consumption of Nitrate raises Alkalinity.

Basically if your tank is processing Nitrate and reducing it by 20ppm it will increase Alk by about 1dKh

 

[Magic031707]

Do you have sand in your tank?

 

[Magic031707]

I am starting have the same issue. Nitrates are steady. Alk still increasing. I am really thinking about removing my sand.

Alkalinity rising without dosing... possible causes?

Well, I will say that removing the sand bed is a maaajor destabilizing event. There's an enormous amount of nitrification going on in the sandbed, microfauna populations etc. When you take that out, the system will need to rebalance itself. During this time I wouldn't be surprised if...

www.reef2reef.com

 

[Drone]

Do you have sand in your tank?

A very thin layer of crushed coral and I vacuum parts during water changes

 

[EricR]

I'm in the same boat (alk increasing with no dosing) for almost 6 months now.
I tested potential sources in smaller tank, one at a time, for several months and never figured anything out.

I'm currently just letting alk rise (on it's own) and then dropping it by about 0.6-0.8 dKH immediately via small water change with low alkalinity new saltwater (mixed with sodium bisulfate) ,,, roughly every 3 days.
*less than ideal but not sure what else to do

I've posted on this before, like here, (but still don't understand so not likely of use):
Alk Rising

 

[Randy Holmes-Farley Verified Community Expert]

I did a 30% two days ago and checked it today and read 15. And to reiterate I’ve never added a drop of alk/kalk or anything to this tank. I get synthetic from my LFS and they use fritz reef pro mix.

Just to be clear. You don't literally say you tested the new water now with the same kit and got a much lower alk level than the tank. Did you?

You aren't using tap water for top off, are you? It can have more alk than seawater.