Why did my alkalinity drop?

[ninjataco777]

my alk last week mas 9dkh now is like 6.5 the only thing i did was add carbon and had my skimmer off for a day. my water is a little cloudy because i just cleaned the tank, could that cause the test to have false readings?

 

[burning2nd]

just my unscientic though.... lack of air?

 

[ninjataco777]

cant be that, got open top plenty of surface current

just my unscientic though.... lack of air?

 

[burning2nd]

overflow? anything to brake the surface tention?

when you look at the water surface from below is it clear?
do you see stuff floating around on it?

 

[Woodstock]

Lots of things/processes use up alkalinity; decaying matter, growing corals, growing coralline algae, etc.. I have to add alkalinity to my reef occassionally.
Make sure you add it VERY slowly and use this chart to determine the amount of 'buffer' to use: Reef Chemistry Calculator

 

[Dentoid]

Dropping Alkalinity can be the cause of several things.

1. If you start raising the calcium disproportionately to alk.
2. Acidification of the water by the breakdown of organic substances.
3. User error in using the test kit.
4. Test kit errors.
5. Buildup of organic and inorganic acids from biological sources.

 

[ninjataco777]

sometimes

overflow? anything to brake the surface tention?

when you look at the water surface from below is it clear?
do you see stuff floating around on it?

 

[Bennyboy515]

I have the same problem on my 60 gallon so i did a 50 percent water change and went from 7 to 9 carbonate hardness immediately then in a week it dropped down to 6. The guy at the lfs told me to check nitrates and sure enough it was in the 20's so i cleaned out my sulfur denitrator and did another 50 percent water change, hopefully one of us can solve this problem still in the 7's

 

[Bennyboy515]

and yes calcium reacts with alkalinity in a constant battle but this is not my case and i have a 160 gallon reef octopus bubble blaster skimmer so oxygen is not the problem. when i first started the lfs told me to add purple up everyday, not okay, not okay.

 

[Reddog170]

when i first started the lfs told me to add purple up everyday, not okay, not okay.

They like to sell things, even if we do not need them.

 

[yvr]

I try to stay away from dkH buffers and it seems like some people tend to use it too aggressively and end up making changes in the water chemistry in their tanks too quickly (in my opinion). I prefer to make any change in the water chemistry slowly over time. Usually a tank that has a low dkH took some time to get down there, it usually didn’t happen overnight. On the other hand, it’s also not good to have it raised to the desired level over night. . I dose my tank with TM Bio-Calcium which will slowly, over time, raise the dkH to the right level at the same time as keeping my Ca where I want it; esentially killing two birds with one stone.

 

[Amnestia]

Different tanks use different amounts of alkalinity, it is possible that your tank uses quite a bit. My old system could have a drop from 9dkh to 7dkh in as little as 2-3 days. The system just used a lot of it, i dosed daily (at the time 22grams of baking soda) to keep alkalinity at a constant 9dkh.

As my sps grew bigger and faster they took up more and more alkalinity.