alk dropped? IDK why?

Ive been running a 40gal breeder for six months on a dosing schedule. I dose for Cal, Alk and Mag. I have done tests about every week since i started dosing and my alk has always been between 10-11dkh. My mag has stayed in the 1500s, and my calcium has stayed between 400-500. So i did my tests this week and realized that my alk has dropped from 10-11 to 8-9 dkh. I also noticed that the dkh in my 14 gal has dropped from 7-8 to 5 dkh. I just did tests on my 14gal and im at mag 1455 and cal 440 . Im really confused as to what is happening. I have been using the same salt mix for my weekly water changes too. Why is my alkalinity decreasing at such a fast rate?

 

Have you added any new corals or inverts?

 

from your description above it seems like demand has escalated beyond your current supply routine

The Calc level you state between 400 and 500 is to extreme a range making it difficult to asses if the situation is abnormaly high Alk demand (fighting low PH issues etc
or if in fact it is linear demand

let us assume your calcium level was over 450 whilst your Alk was 10- 11
now your Calcium is 420 , that in itself would balance out with the 2 DKH reduction
(typically in a reef set up, there is only about 7ppm drop in calcium for every 1 degree of DKH reduction)

thus my opinion is , you need to increase the amount of both calcium and alkalinity you are adding

what form of additions are you using?
what method of dosing are you doing (manual or automated )?

Steve

 

Hey Steve. Thanks for chiming in. This is happening in two tanks.

50gal system

12-13-11
​

Mag 1620
Cal 490
Alk 10-11

12-29-11
Mag 1575
Cal 490
Alk 8-9

16gal system
12-13-11
Mag 1425
Cal 420
Alk 7-8

1-2-12
Mag 1455
Cal 440
Alk 5

I have added some sps frags to the 16gal on 12-10-11 and they are doing great. I have added nothing new to the 50gal except three new fish around the 1st of December. But i have heard that alot of peoples ph and alk drop in the winter when there is less oxygen indoors because of the decrease in fresh air being introduced through open windows and the like. Do you think this is true? And if so how would you remedy it? Kalkwasser? How would one add more oxygen to the tank besides more surface agitation or a skimmer? Maybe an airstone? Idk.
My Calcium is still at 490 with my ALK at 8-9.
I am using Bulk Reef Supply 2 Part Solution that raises ph.
I have a automated Bubble Magus doser.

Thanks for the help

 

Hi Crusty - certainly PH can be an issue during winter due to closed up living accomodation
one method used is to run air from outside into the skimmer via a longer air line
adding extra sources of surface movement can help, and airstone in the sump for example
opening the windows for brief periods during warmest part of day can also help to get fresher air into the room

the 50 gallon system seems somewhat stable , allowing for test kit user variation
the 16 gallon - might want to double check that Alk reading as it is very low and possibly a test kit error
the calcium has increased by 20ppm and that could account for a drop of that nature
depending on your SG? as with an SG of about 1.025 - 1400 plus Mag should support your original numbers OK, but with a lower SG , it may be a case of to many Ions fighting for space thus the increase in both Mag and Calcium has pushed your carbonates out of solution

bear in mind in terms of utilisation as low 7ppm calcium can be consumed for every 1 dkh
and 7ppm Calcium is not something your average hobbyist test kit/ hobbyist combination can accurately record

so when making any increase on your Alkalinity supplement, it is often a case that you actually need to increase the numbers of both this and calcium

Steve

 

Ok. ill try to raise my calcium up just a little bit and than see if i can raise up my alk. I tried to raise my alk with some Seachem reef buffer and i am still getting the same reading? It was 60deg today in Colorado so i was able to open my windows for a few hours. Ill report back. thanks

 

On the 16 Crusty , I would check the SG and target 1.025

if it is at that, then supplementing Alk 1st would be good
440 is fine for Calcium

once you have 440 and 8 or 9 - your fine
and then dose equal ratio parts of calcium and Alkalinity to maintain

 

ok cool. i just came across a Tom Aqua Lifter. Do those work well for dosing? I have been using a simple u shaped drip from a cup with a gate on it.

 

ok. so i set up a dosing regime to raise my alk from 6-7 over a 24 hour period. I am using bulk reef supply soda ash. I used their reef calculator and it said to use 7.1 ml to get a raise of 1 dkh. So i dosed 1ml every four hours. I tested the water about 12 hours later and i got a raise of about 1dkh. I went ahead and followed this same dosing regime for another two days to raise my alk to 10. I did my tests afterwards and i got a result of 10-11 dkh. Than i didnt dose for 36 hours, just tested my alk again and we are back at 7 dkh.
mag is at 1425 and calcium is at 420, sg is 1.026
So should i try to raise my calcium up to 440 or so?
Or should i just try to do the math and set up a dosing schedule for my alk by using the amount it declined over the last 36 hours?

 

I would get a second opinion on the test before making any changes. Are you corals freaking out? I know when I mess up a dosing regimen because I lose polyp extension, color, and sometimes stn. If the only issue here is you are testing low, get a second test. These things go bad sometimes.