Help, my alk is rising?

rueric · Feb 13, 2022

Hi All,

I need some help solving a mystery...
My alk is rising after water changes.

Just completed my gamut of testing for the night, here are the results and some background on the tank itself.

Salinity: 35.2 (Tested using Hanna Salinity Checker)
Phosphate: .42 (Tested using Hanna ULR)
Nitrate: 9.8 (Hanna low nitrate test)
Alkalinity: 214PPM (12 dkh, tested using Hanna)
Calcium: 423 (Hanna tester)
Magnesium: 1350 (Aquaforest test)

The tank has been up since July 2021
Feeding consists of Hikari Seaweed Extreme pellets (twice a day)
twice a week target feeding of reef roids
- Likely going to try using Benepets instead of reef roids for phosphate

I run a skimmer with a small refugium, JUST bought a new light for it since my dragons breath was only getting about 50 par.

The salt I use is Red Sea blue bucket, I've tested the water, it measures accurately to what the redsea batch results show, 8dkh

Is it my substrate that is raising my alk?
What is my course of action here?
After a 30% water change two weeks ago (11.5dkh at the time), I was hoping my water change would help stabilize the tank but it's not working..
I'm not dosing anything (previously dosing All for reef) but stopped a few months ago now since I started to see my alk rising.
Everything in my tank appears to be fine with the exception of a hammer that is not really extending.
For my chemical filtration, I'm using Chemipure blue with seachem matrix and filter floss.

Should I try dosing vinegar?
Do another large water change?

Help!

Jekyl · Feb 13, 2022

Get a second opinion of the test imo. If your salt is 8dkh and you're not dosing it just seems weird.

Jekyl · Feb 13, 2022

Other question would be if you're sure of the salinity.

rueric · Feb 13, 2022

I have a second tank in my office, tests for that tank all came back normal

rueric · Feb 13, 2022

@Randy Holmes-Farley help?

Lavey29 · Feb 14, 2022

Your PH is off

Miami Reef · Feb 14, 2022

Here’s some quotes from Randy 2016:

Are you using tap water for top off? Are you maintaining the water level so salinity is not increasing day to day?

The only way that alkalinity increases in a reef tank aside from additions of some sort (even if you do not know what additive or water source might contain it) is if nitrate is falling due to consumption by organisms. Reduction in nitrate of 50 ppm will increase alkalinity by 2.3 dKH.

I don't believe your pH actually reached 8.8 unless you overdosed alkalinity greatly, but daily changes in pH won't alter the alkalinity. I do not expect it impacts the Hanna measurement, but it is not a normal titration for alkalinity and I'm not certain how pH impacts its measurement. Hanna has told me it doesn't, but I cannot independently confirm that.

I should have mentioned that artificial rock made from cement can also raise alk until fully cured. Do you have cement in the tank?

Both quotes from here.

rueric · Feb 14, 2022

I dosed chemi-clean maybe about 2 months ago now, but my nitrates have been pretty stead at <10 for the past few months.

No artificial rock, all dry rock since cycling.

Would something like F-Aptasia cause this? I used that maybe about 5 months ago.