Why is my alkalinity suddenly dropping?

Joe Batt

Active Member
View Badges
Joined
Apr 15, 2017
Messages
495
Reaction score
284
Review score
+0 /0 /-0
Location
Dubai
My alkalinity as suddenly started to drop like a stone, but no sign of precipitation, and dosage goes into good flow area. I don't know why.

I maintain my kH around the 7.8-8 dKh mark. My Ca 420 and Mg 1230. I dose Triton methods Core 7.

I was away for a week and my pH increased from 8.2-8.3 to 8.3-8.4. The last few days the alkalinity demand seemed to skyrocket from 20ml of 3a&3b Core 7 combined to nearly 40ml, and even then there was a gradual drop of the dKh to 7.6 dKh My tank is lightly stocked with a variety of LPS and SPS corals of small size. No matter what I dosed the demand still seemed to increase. It seemed way too high, and I suspected a problem so cut off all dosing for 2 days. The kH dropped from 7.6 to 6.4dKh.

Previously the tank had been very stable, with a slow gradual increase in 3a&3b usage.

Please help
 
Top Shelf Aquatics
OP
Joe Batt

Joe Batt

Active Member
View Badges
Joined
Apr 15, 2017
Messages
495
Reaction score
284
Review score
+0 /0 /-0
Location
Dubai
Nope not dosing vinegar I have a very effective thriving fuge. My nitrates are generally very low around 2-5ppm, I haven't checked them but doubt any change in that value.
 

Martin Kuhn

Active Member
View Badges
Joined
Sep 21, 2016
Messages
228
Reaction score
105
Review score
+0 /0 /-0
Most likely that’s good news. Your stone corals start growing faster then before. As a result the calcium carbonate consumption goes up.

Dose more :)
 
Click to watch best scape method in 5 easy steps!

Randy Holmes-Farley

Reef Chemist
View Badges
Joined
Sep 5, 2014
Messages
45,433
Reaction score
34,494
Review score
+0 /0 /-0
Location
Arlington, Massachusetts, United States
20ml of both 3a and 3b (40ml daily) seems a huge amount....and to go up so quickly seems strange.

Without knowing the tank volume, or much better yet, how much in dKH per day these additions are calculated to boost alk, I can't know whether it is a small addition, or a huge addition.

The drop from 7.6 to 6.4 dKH in 2 days is not particularly unusual, but is hard to gauge as demand drops off fast as the actual alk drops through the 6's.

In general, an increase in demand can be caused by a lot of things, including nutrient and pH changes in the tank, but is not usually a bad thing unless the sand seems to be hardening or some such thing that demonstrates a big increase in calcium carbonate precipitation. Dosing pump changes in dosed amounts also sometimes explain changes, despite the same time being on.
 
OP
Joe Batt

Joe Batt

Active Member
View Badges
Joined
Apr 15, 2017
Messages
495
Reaction score
284
Review score
+0 /0 /-0
Location
Dubai
Apparently 2ml of 3a&3b increase the dKh by 0.195 in 100 Ltr. My tank is approx 320 litres liquid volume.

Thus I was dosing 20ml per day which equates to 0.61 dKh in my tank. Within a few days it jumped to 40ml equating to 1.22 dKh per day.

The tank has around 35 frags. Mixed LPS SPS with a few half palm sized.
 

Randy Holmes-Farley

Reef Chemist
View Badges
Joined
Sep 5, 2014
Messages
45,433
Reaction score
34,494
Review score
+0 /0 /-0
Location
Arlington, Massachusetts, United States
Apparently 2ml of 3a&3b increase the dKh by 0.195 in 100 Ltr. My tank is approx 320 litres liquid volume.

Thus I was dosing 20ml per day which equates to 0.61 dKh in my tank. Within a few days it jumped to 40ml equating to 1.22 dKh per day.

The tank has around 35 frags. Mixed LPS SPS with a few half palm sized.

That's does not seem excessive to me, and I'd just dose it. Even a soft coral tank can use 2 dKH per day.

Why did it change? Not sure. Might just be more growth for some reason.
 

Do you house a "Reef Safe" Angelfish in your reef tank?

  • YES and it's going good

    Votes: 174 41.9%
  • YES but it's not working out

    Votes: 12 2.9%
  • NO I have tried it in the past and it didn't work out

    Votes: 35 8.4%
  • NO I haven't tried yet

    Votes: 180 43.4%
  • Other (please explain)

    Votes: 14 3.4%
Motorcitycorals
Top