High Alkalinity

Aquatalk · Jul 4, 2019

Hi all! My tank is two months old and for the most part I am please with it. One problem I am having is the alkalinity keeps moving up. I have tested every three to four days and in a months time the Alkalinity has increased from 8.0 to 10.1. I can’t think of why this is happening. The saltwater I use tests at 7.3. What gives?

watdachuck · Jul 4, 2019

What method of testing are you using to determine these levels, and have you tested your fresh salt water every time or was the 7.3 a one time thing? IORC have an alkalinity closer to 10 for instance.

Are you dosing anything to the tank at this time, or just water changes?

It looks like the change has been a steady increase over roughly 2 months.

Aquatalk · Jul 4, 2019

watdachuck said:
What method of testing are you using to determine these levels, and have you tested your fresh salt water every time or was the 7.3 a one time thing? IORC have an alkalinity closer to 10 for instance.

Are you dosing anything to the tank at this time, or just water changes?

It looks like the change has been a steady increase over roughly 2 months.

I use the Hannah checker dkh. I’ve been using the same saltwater the whole time. I buy it from the lfs. I tested my RODI water last night to see if maybe something had contaminated it and it was at 10.3 which was shocking. So, I took some RODI water to my friend to let him test it and come to find out the Hannah checker vials were dirty I guess because we cleaned them and it read 0.0. I came home and tested my tank water two more times and both times read 10.1

LesPoissons · Jul 5, 2019

what are you using for top off water? did you test that? If its been a slow rise over a couple months, I would test that and see.

Is your ph typically 7.8? Sometimes if Ph drops, different elements from the sand bed can be released but I think it needs to be much lower than that.
What is your calcium? If it is out of balance with your mag, that can affect the reading you get with your alk.
Where are your nitrates? If nitrates drop from 100ppm to 50ppm, that can account for an increase in 4 to 5 from alk.

Usually Alk doesnt rise on its own, so something is causing it. I would guess your top off.