Alkalinity goes...up?

[HarrisonMG]

I mix all my water with ReefCrystals
And that gives the water an alk of about 11 dkh.
So that's fine and all, but in my quarantine, the water rose from 11dkh to 15dkh in just a couple of days--and without me doing a thing.

This killed my entire 8" Monti, plus a green trumpet.

Last week, the water in my DT was about 8.5dkh. Now, again, without doing anything, even a water change, it's up to 10dkh.

Can anyone explain this to me? When I went to my LFS, they said that alk should naturally go down over time!

[bertoni]

Alkalinity won't rise unless something is added to the water column. pH buffers and tap water are typical stealth sources of alkalinity. 15 dKH shouldn't kill corals that quickly, not without something else happening. That seems strange.

[ramseynb]

Or water evaporation. If you're allowing water to evaporate and not replacing it with fresh water, I could see those levels rising. Is your salinity rising as well?

[HarrisonMG]

Alkalinity won't rise unless something is added to the water column. pH buffers and tap water are typical stealth sources of alkalinity. 15 dKH shouldn't kill corals that quickly, not without something else happening. That seems strange.

I added nothing, I swear! (Except food I guess...)

I have a whole other thread about my Monti:
http://www.reefcentral.com/forums/showthread.php?t=2675511&goto=newpost

As for water evaporation, I have a tight fitting lid so very little escapes and the amount that does, I do replace with freshwater.

[bertoni]

I'd guess that you're seeing a measurement problem, then, unless there's some alkalinity in the food, which seems unlikely. I would look for other causes for the coral death, in any case, since 15 dKH seems safe enough on average. That might not hold for tanks with some sort of carbon dosing or other nutrient reduction, but the coral decline seems very rapid, from what you have said.

[HarrisonMG]

I have tested many times and with multiple test kits, Api and Salifert.
Now QT is down to 13

[bertoni]

Have you checked the pH? If the lid is very tight-fitting, that might limit air circulation, which might cause some testing issue, although I'm skeptical about that.

Something needs to dissolve into the water to increase the alkalinity. What is in the tank?

[Tripod1404]

I am also inclined to think that it is a measurement error.

Do you get any precipitation or have any type of substrate or rock inside your tank? The only thing I can think of side from measurement error is alk somehow precipitating as calcium carbonate and the redissolving or your substrate/rocks that contains CaCO3 is being dissolved.

But that should not normally happen as alk is calcium carbonate very insoluble in + ~pH 7 and it is very very hard to drop the pH of sea water below that. I doubt it, buy maybe by tight fitting a lid you are causing pH to drop and solubilizing calcium carbonate (if you have any).

[HarrisonMG]

Lid isn't air tight, just covers most of tank. Probably a 3x12" gap where surface is exposed to air.
Forgot to mention that I measured a few different times and then my LFS measured and got the same result.
Only things in water are plastic decorations from Petco I've had for years, PVC railing, and two Terra Cotta pots. Nothing is falling in.

Ph is good at 8.3

[bertoni]

I'd just ignore the alkalinity. I don't think that terra cotta can leach alkalinity, although cement-based artificial live rock can. I suspect some sort of testing issue, but I can't imagine what it is. Those alkalinity levels you mentioned all should be safe enough.

[HarrisonMG]

Yeah, safe for fish but not for corals. My 8" Monti went 100% RTN on me overnight once I stuck it in there.

[bertoni]

That's possible, although some number of years ago, people ran tanks at 18 dKH regularly. I don't know what the tolerances of our corals might be.

[HarrisonMG]

So it's been almost a month. My QT alk is stuck at 11dkh. Should I just try again with the Monti and if it does fine go for more corals?
Or should I do something to the water too lower since the reef place keeps 8dkh?

[Lsufan]

If the corals are coming from 8 dkh water then I would have the tank they are going to at close to the same levels. I keep my tanks at about 7.5 to 8 dkh because that is where most places I get corals from keep alk. I also have low nutrients which is another reason for keeping a lower alk. That is why I use regular instant ocean & not reef crystals.
U don’t want to get a sps coral that is in a tank with 7 dkh & throw it in a tank that has 12 dkh. If the coral isn’t 100% healthy then chances are it will have issues from the alk swing. Even healthy corals can have issues with a alk swing.

[bertoni]

I'm not sure how much difference that shift in alkalinity would make. You could use some muriatic acid to lower the dKH, but muriatic acid requires some care in handling and storing. If the coral seems okay, I wouldn't bother.

[HarrisonMG]

Well the first time I tried it the coral WAS NOT OK. actually three of five corals survived and thriving in DT. but other two are long gone. Probably gonna go the route of muriatic acid and switch to a different salt once I run out.


Sent from my iPhone using Tapatalk