Alkalinity hasn't changed in 2 weeks.

[Cory]

I don't have any corals that use calcium and all but I've got two big live rocks covered in corraline. I thoughts he alkalimity would reduce from that at least. Every time I check with salifert i get 8dkh. What gives?

 

[ritter6788]

Just not enough demand. Add some sps or a clam and it will be used up much faster.

 

[Randy Holmes-Farley]

Maybe the coralline isn't growing rapidly, or there just isn't that much of it.

 

[Cory]

I don't know guys. Po4 is completely clear on Salifert, nitrates are in the 5-20ppm range. Maybe my cheap Chinese led ich blue and whites is not sufficient in par. Anyone heard of them being poor? The corraline has that whitish outer edge wich looks like new growth.

 

[Noob]

just as already stated, i assume there isn't enough demand. i know when i had zoas only in my tank, my dKh didn't change much week to week either. but once i started adding acros, it started taking a huge dip.

 

[Randy Holmes-Farley]

What do you use for top off?

 

[Cory]

Just ro/di Randy. I boost the alk with baking soda when necessary via drip.

IM assuming that bacterial acidification would at least lower it by a few points, not to mention te corraline algae. Maybe my small addiotons of iron glauconate are maintaining it? But I don't dose much, just .1ml every 3-7 days. That's one pill in 300ml water.

 

[Randy Holmes-Farley]

Bacteria only reduce alkalinity when they are producing nitrate. But the consumption of that nitrate by other bacteria or macroalgae gives it back.

So when nitrate is not rising, the alkalinity isn't altered by overall bacterial processes.

While the gluconate will boost alk, the amount is likely incredibly small.

 

[Cory]

Hmm well Im going to say there isn't enough calcification going on then!

If I understood you correctly Randy, your saying that macroalgae and some bacteria produce bicarbonate when they consume nitrate, so there is no change in alkalinity due to nitrification? If that's true that's awesome, but would require no3 to be consumed at the moment it's made.

 

[Randy Holmes-Farley]

It wouldn't have to be simultaneous for a given ion. Just happening at the same rate overall. So if nitrate is held constant, there is no ongoing impact to alkalinity.