What causes rapid consumption of alk?

[KustomAquarium]

I have a 220 gallon system and I burn through about 2 dkh a day. Any ideas what might be using so much alk? I have about 16 frags, a small clam, average clean up crew, 4 btas(they split often) and about a dozen fish.

My ph hovers at 8.0
Dkh is usually 8.6
Calcium is 435
No3 .35
Po4 .18
Last time I checked mag was 1550

 

[plankton]

All your biological activity especially clams burn through alk like crazy.

 

[sfin52]

Coraline will chew through alk.

 

[Doctorgori]

YeAh that clam looks guilty, this is unless your 2pt doser outlets have somehow moved next to each other

 

[KustomAquarium]

I had been using sodium bicarbonate cause I had an issue with the soda ash precipitating out. I am now using Tropic marin carbo calcium, but I'm taking it slow and adjusting with the sodium bicarbonate until I have the exact dose down on the carbo. But the clam is legit like 2.5" he is small, my Coraline has never really taken off, i have blotches of it but I can't see my tank going through almost 700ml of sodium bicarbonate a day? (Since I switched to carbo the most I've put in is 250ml to bring the alk back up to my 8.6)

 

[blasterman]

Alk is consumed massively by growing bio stratas including bacteria and many algaes. Where do you think bacteria in our tanks get their carbon building blocks from from? Ditatoms especially will devour it. If you are wiping brown stuff off your glass that's a good indication.

This sounds like a young tank, and I have money on your calcium not moving at all. So, there it is. A big reason I am such a harsh critic of two part dosing kits which are darn near false advertising and approaching the snake oil category.

When your tank matures alk will stabilize. Until then keep using regular baking soda and not using the over priced moron-magnet stuff in the pre packaged bottles. It's just baking soda dissolved in water. Soda ash might be too much right now, so good correction on that front.

Buddy of mine has a 200 gallon with a clam over a foot long. Tank doesn't consume anywhere near as much alk as your because it's 7 years old.

Coraline doesn't consume alk in any different ratio than stony corals.

 

[Randy Holmes-Farley Verified Community Expert]

If you do not see abiotic precipitation of calcium carbonate hardening the sand or on pumps, etc, then the demand is likely from organisms,. A soft coral tank can use 2 dKH per day from coralline alone.

If you are concerned about abiotic precipitaiton, then ways to stop it are:

1. Stop dosing alk for a bit and let it decline.
2. Reduce pH by switching to a low pH alk mix like sodium bicarbonate, or a calcium organic such as Tropic Marin All for Reef.
3. Ensure magnesium is normal to high.
4. Keep organics and phosphate on the high side.

After a few days of not dosing alk, restart slowly, adding additives to a very high flow area so it mixes in fast.

 

[Randy Holmes-Farley Verified Community Expert]

Alk is consumed massively by growing bio stratas including bacteria and many algaes. Where do you think bacteria in our tanks get their carbon building blocks from from? Ditatoms especially will devour it. If you are wiping brown stuff off your glass that's a good indication.

It is not correct that bacteria consume alkalinity (except nitrate production, see below).

Diatoms only consume alkalinity as they consume silicate. They are not consuming carbonate alkalinity (bicarbonate or carbonate).

The production of nitrate from ammonia will consume alkalinity, so if nitrate is rising fast, that depletes alkalinity.

 

[KustomAquarium]

It is not correct that bacteria consume alkalinity (except nitrate production, see below).

Diatoms only consume alkalinity as they consume silicate. They are not consuming carbonate alkalinity (bicarbonate or carbonate).

The production of nitrate from ammonia will consume alkalinity, so if nitrate is rising fast, that depletes alkalinity.

So I do clean my glass often, I'd say every couple of days and there is a little film on it, my tangs graze constantly on the rocks and substrate, I also feed more than I should IMO. Ido have a rather large refugium and a great skimmer though. Would it be safe to assume that despite my nitrates being at a acceptable range, the algae and possibly diatoms are using the po3 and po4 faster than I can test for them? And that is possibly the reason I'm using so much alk?

 

[Randy Holmes-Farley Verified Community Expert]

So I do clean my glass often, I'd say every couple of days and there is a little film on it, my tangs graze constantly on the rocks and substrate, I also feed more than I should IMO. Ido have a rather large refugium and a great skimmer though. Would it be safe to assume that despite my nitrates being at a acceptable range, the algae and possibly diatoms are using the po3 and po4 faster than I can test for them? And that is possibly the reason I'm using so much alk?

I don't see nutrient levels or algae growth being particularly related to alkalinity. As I said, those organisms are not using alkalinity. They cannot.

 

[KustomAquarium]

I don't see nutrient levels or algae growth being particularly related to alkalinity. As I said, those organisms are not using alkalinity. They cannot.

Sorry I must have misinterpreted, I was asking more along the lines of the rapid production of nitrate from ammonia, this could consume the alk?

 

[Randy Holmes-Farley Verified Community Expert]

Sorry I must have misinterpreted, I was asking more along the lines of the rapid production of nitrate from ammonia, this could consume the alk?

Yes, but nitrate has to be rising. I didn't explain it well. If nitrate is consumed it gives all the alk back.

Any steady level of nitrate is not impacting alk. If it rises by 50 ppm, alk is depleted by 4.5 dKH. If nitrate drops by 50 ppm, it adds 4.5 dKH.

 

[KustomAquarium]

Yes, but nitrate has to be rising. I didn't explain it well. If nitrate is consumed it gives all the alk back.

Any steady level of nitrate is not impacting alk. If it rises by 50 ppm, alk is depleted by 4.5 dKH. If nitrate drops by 50 ppm, it adds 4.5 dKH.

Ok so it's not being used up per se, just borrowed?

 

[Randy Holmes-Farley Verified Community Expert]

Ok so it's not being used up per se, just borrowed?

Yes.

 

[Jlaserbeam]

I have a 220 gallon system and I burn through about 2 dkh a day. Any ideas what might be using so much alk? I have about 16 frags, a small clam, average clean up crew, 4 btas(they split often) and about a dozen fish.

My ph hovers at 8.0
Dkh is usually 8.6
Calcium is 435
No3 .35
Po4 .18
Last time I checked mag was 1550

The clam