Alk use in soft coral tank

[Gungnir]

My tank is currently a lightly stocked soft coral tank, but I eventually plan to keep LPS as well. When I first started testing for alkalinity, it was quite low and I have been working on slowly raising it with aquavitro 8.4; which was recommended by my LFS. I am thinking of moving to BRS two-part dosing for the long run-- likely starting with just alk dosing then adding calcium when necessary.

Anyway, my tank seems to be using alkalinity, but on what? Snail shells, diatoms, spirobid worms... It is possible that nothing is actually using alkalinity and it is some measurement error that is making it seem so.

It will be a little while before I look to add LPS corals, but I would like to have stable parameters and a clear understanding of tank dynamics before attempting to add them. At this point, it seems I need to add alkalinity, but I am not sure why/what is using it.

Here is what I have seen over the last few weeks:
1/13: alk=5.7 dkh
1/14: started dosing max recommended dose of 8.4 (7mL for 32g)
1/15: alk=6.1 dKH, dosed 8.4
1/16: alk= 6.3dKH, dosed 8.4
1/18: alk=6.5dKH, dosed 8.4
1/19: water change 5 gallons in 32g cube (source water alk=8.7 dKH, added some 8.4 bringing it to 9.6dKH)
1/20: alk=7.0dKH
1/21: dosed 8.4
1/24: alk= 6.9dKH, dosed 8.4
1/25: dosed 8.4
1/27: alk=7.0 dKH, dosed 8.4
1/28: dosed 8.4
1/29: alk= 7.2dKH, dosed 8.4
1/30: dosed 8.4
1/31: dosed 8.4, alk=7.9 dKH (*the only time I dosed before measuring--- I waited about an hour before measuring, but normally measure first)
2/2: dosed 8.4
2/3: alk=7.3dKH, dosed 8.4

Other tank details:
Calcium levels have stayed at ~430ppm (Salifert)
Magnesium levels have stayed at ~1290ppm (Salifert)
Alkalinity measurements from Hanna checker
Nitrates, Nitrites, and Phosphates have stayed at 0 ppm (ppb for phos) [started feeding more to try to get these levels up slightly]
Salinity 1.025
Temp 78F
Small refugium with chaeto

Corals:
Cespitularia
GSP
Xenia
Zoas (added 2/2)

Fish:
2 clowns
1 firefish goby

CUC:
5 snails
5-8 hermit crabs

 

[Jeff Jarry reef]

How old is your tank and do have Coraline algea growing. Or any precipitation. Any white Crist on pumps heater's.

 

[Gungnir]

Tank is 2 months old. No coralline or white crust/precipitation other than the spirobid worms that are on the back of the DT, rocks, snail shells, etc.

 

[lapin]

What I have observed, is while a new tank matures, it will use alk and calcium even if you dont have LPS, SPS. It will stablize at a certain point. For the first few months its an up and down cycle for me.

 

[sfin52]

What I have observed, is while a new tank matures, it will use alk and calcium even if you dont have LPS, SPS. It will stablize at a certain point. For the first few months its an up and down cycle for me.

Does that also translate to tank upgrade with everything be transfered over to the new tank.

 

[Dr. Dendrostein]

What I have observed, is while a new tank matures, it will use alk and calcium even if you dont have LPS, SPS. It will stablize at a certain point. For the first few months its an up and down cycle for me.

I wonder if it's the anaerobic bacteria consuming it. Or aerobic bacteria. Just a hunch, me thinking out loud

Scleronephthya 12 inches tall, just imported from Indonesia to Europe courtesy of @najer it's his coral

 

[Randy Holmes-Farley Verified Community Expert]

I wonder if it's the anaerobic bacteria consuming it. Or aerobic bacteria. Just a hunch, me thinking out loud

Scleronephthya 12 inches tall, just imported from Indonesia to Europe courtesy of @najer it's his coral

Bacteria don’t generally consume alkalinity unless nitrate is rising. Production of nitrate depletes alk a bit, and organisms using it adds it back.

A soft coral tank can use 2 dKH per day from coralline algae, calcium carbonate spicules in soft corals, snails, lots of other creatures, and abiotic precipitation on pumps, heaters, etc.

 

[Gungnir]

Bacteria don’t generally consume alkalinity unless nitrate is rising. Production of nitrate depletes alk a bit, and organisms using it adds it back.

A soft coral tank can use 2 dKH per day from coralline algae, calcium carbonate spicules in soft corals, snails, lots of other creatures, and abiotic precipitation on pumps, heaters, etc.

Thanks, this helps assuage my concerns! I will keep measuring and dosing as the tank requires.

 

[Dr. Dendrostein]

Bacteria don’t generally consume alkalinity unless nitrate is rising. Production of nitrate depletes alk a bit, and organisms using it adds it back.

A soft coral tank can use 2 dKH per day from coralline algae, calcium carbonate spicules in soft corals, snails, lots of other creatures, and abiotic precipitation on pumps, heaters, etc.

Ooooh close call, I have nps corals so my consumptions a lot less. Close call. thank you big cheese, I mean Randy....heeee

 

[lapin]

Does that also translate to tank upgrade with everything be transfered over to the new tank.

I have never done that. I have always started with some new and old or all new, so I cant say it will or wont happen

 

[sfin52]

Bacteria don’t generally consume alkalinity unless nitrate is rising. Production of nitrate depletes alk a bit, and organisms using it adds it back.

A soft coral tank can use 2 dKH per day from coralline algae, calcium carbonate spicules in soft corals, snails, lots of other creatures, and abiotic precipitation on pumps, heaters, etc.

So let's say you have an alk at 9 by the end of the day it will be 7?

 

[Randy Holmes-Farley Verified Community Expert]

So let's say you have an alk at 9 by the end of the day it will be 7?

I’m saying that some folks with nice soft coral only tanks will drop 2dKh in 24 h. Coralline algae may be the biggest user in those, but we have no easy way to know exactly what organism is using the most.

 

[Dr. Dendrostein]

I'm not usually awake this early in the morning it's 3:57 a.m. here, but I think I have some bad McDonald's, breakfast you know. very gassy

 

[fragit]

I would also check that your sand (if you have it) is not turning into cement. Had the same issue when my tank started only I made bricks in some areas from precipitation.

 

[Blknovass]

I had a similar issue. I changed my salt to Tropic Marin and things seam to be more stable. I do a 5% water change weekly. Don’t know if it was coincidence or not but that’s what helped me. I had a 29 gal bio cube.

 

[Gungnir]

I had a similar issue. I changed my salt to Tropic Marin and things seam to be more stable. I do a 5% water change weekly. Don’t know if it was coincidence or not but that’s what helped me. I had a 29 gal bio cube.

Thanks- just received my first bucket of TM today!