where is my alkalinity going??

[Jack_L]

thanks, it seems that way to me too. i moved my light to more white, been on my to do list. lost my yellow watchman goby, and a steady marching of snails ever since i pulled the carbon. i see TONS of different microfauna under thet scope, so at least that is good, but it doesn't seem to matter.

 

[JonasRoman]

hi, my tank is about 5 months old now, uglies still around some. its 140gals of water. i do 10% weekly water change. i just have small frags, the tank looks empty really
the are two small SPS, a birdsnest and a sytlo, trumpets, several frags, couple small cononlies of 15 heads, but in total, i'd say about 1 softball size. also tiny zoa and 3 mushrooms.
i have some fish.
3 firefish gobies, 2 cardinal, 1 tang, 1 clown gobie, 1 watchman, 1 sleeper gobi ,2 clowns, 2 peppermint shrimp, 1 pistol shrimp, 2 emerald crabs and i guess about 100 snails, certith, astrea, nassarius, trochus,

my ALK has been dropping, it was down to like 6. i realized i wasnt' mixing salt strong enough, i fixed that. and i've added seachem reef builder to get it back up too, but being new to salt, wondering if this this normal. i've been testing it more and i can see a small drop every couples days. i'm guessing from what i'm seeing it would drop over a full point in a week. calcium is dropping a little too, like 10 points every couple days.

basically i was wondering if this is normal, i thought with this much water, and doing WC every week, i would not need to consider dosing until a year or more out if/when my corals were really growing. to date, i've only seen growth in the birdnest.

thanks

A biological system consumes alkalinity not only because of calciumcarbonate formation, but also because of bacterial activity and metabolic activity, which consumes alkalinity. For instance as long as nitrification dominates over denitrifiaction we get a nettoconsumption of alkalinty as nitrification produce H ions that deplete alkalinity. That part dominates the alk consumption long time. Once coral get to grow and you get more corals, that part will also contribute to alk consumption, but not so much the first period.

Alk replacement must therefore be started almost immediately even in a newly started tank. So your scenario is normal.

Concerning algue/dino photosynthesis: CO2 production or consumption will NOT affect alkalinity. It could look like that at a first glance but it will not. For instanee, if you add CO2, both a HCO3 and H will formate, leading to +-0 when coming to alkalinity. same if you withdraw CO2.


Jonas