Dose alk and it goes down


New member
Hello all.

I have been reefing for a long time but I have a perplexing problem I can't figure out so I am asking for help.

I am trying to raise my alkalinity but the more I add the more it drops.

Ok parameters:

Alk 7

Calcium 400

Magnesium 1420

PH 8.04

No matter what I do the alkalinity drops with dosing it does not rise.

I am using an API KH test solution.

Anyone have any input here because I have no clue. There is no buildup on my heater, pumps or anything. I am dosing Randys two part recipe two alkalinity at the rate by the calculator. I am dosing slow and in a high flow area of my sump. I am only trying to raise (1) dkh per day but the more I try to raise it goes down not up.

I have a total water volume of 75 gallons and 10 small (1 inch or smaller) Acropora frags.

I have no clue what the issue is.

Any input will be greatly appreciated.


New member
I forgot to mention I was dripping Kalk at evaporation replacement level for several days.

I had been adding two part in equal amounts until I found that my alkalinity was headed south and my calcium level was good so at this time I am just dosing the alkalinity part.

I have roughly 80 gallons and per the calculator it's says to raise (1)dkh it's 3.3oz. I added the first dose yesterday morning slowly over the course of an hour waited an hour and then tested and there was no change in my Dkh if anything is dropped slightly. I added another dose last night waited an hour to test and again no change it's like I am stuck at 7dkh.

I tested some tap water to make sure my test kit is good and it registered around 6 which is what my tap water is and the test kit is brand new I just got it a week ago.

All SPS look good nobody stressing or anything but I have stopped dumping alk and calcium in until I get a handle on what's going on here.\

Also when I dose two part I add the two parts spaced out at least an hour of each other if not longer.

Thanks for any replies or info anyone provides.


New member
Dosed 3.5 ounces an hour ago and just tested. 7

I tested my supplement and it's over 14 when I quit testing so that is not the problem.


The plot thickens. I just tested my QT tank which I know was north of 8 and has nothing and I mean nothing in it and it tested 7. Maybe a bad test kit?
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New member
the concentrated alkalinity solution should test way over 14.....either the test kit is bad or the solution is bad...


Premium Member
I would try dosing 5 gallons or so of fresh saltwater using this calculator:

Test before and after dosing. If the dKH doesn't rise, then you could try dosing some baking soda. If the baking soda doesn't raise the dKH, the test kit is bad. Otherwise, something is wrong with the supplement.

I get about 2 tsp of baking soda to raise the dKH of your 75 g (water volume) system by 1 dKH. I'd try that next. I'd measure before and then after. You should be able to get a good sample 30 seconds or so after dosing. I wouldn't wait very long.


Crab Free Zone
Premium Member
Logically, it does not make sense.
Are you sure your testing kit is OK?
Are you sure your sup is OK?
Before I changed to Hanna for AlK, my API told me my AlK was 8, forever, never changed.
In fact the Hanna measured at 160ppm which is in the 9.0 dkh range.
Just checking


New member
Good call Uncle99.

Just picked up a new Calcium test kit. The one I was using was reading 380 so I kept dosing to get up to around 400. New test kit says the calcium is 500 or over. No wonder I have a problem.

I wonder how accurate my Alk test is. Tried to get on of those but because I live in Gods country no one had one so I'll have to order online.

My next port of call is ordering Hanna checkers.


New member
Got my Hanna alkalinity tester today and tested.

Alk 5.7DKH - not good.

So my next question and I think I know the answer but I am asking. If my calcium is sky high that would definitely effect the Alk correct


Premium Member
You can use two syringes (or more) of the final reagent to get a reading on your calcium level. If it's high enough, it can cause calcium carbonate precipitation, but that's fairly rare.


New member
My calcium was over 500 due to a faulty test kit. As I added alkalinity supplement upon closer inspection I did see build up on my heater and return pump.

I have since stopped adding calcium supplement and am just adding alk supplement slowly to try to get the alk back up to the 7 range.