Alk Consumption?

Caseyoidae · Jun 8, 2016

My alk has been floating right around 10 dkh for the past month or so but Sunday (4 days ago) I added a large football sized birdnest. Previously had 4 sps frags, various large softies and a few decent sized lps colonies. Water tested at 10dkh two days ago and 7.6 today. Could this coral being sucking that up? If so what's the best way to dose alk back in to the system. I got the calcium up to 450 with kent liquid calcium( calcium chloride) very slowly. (went overboard I guess) Mag has always been high around 1600 too? Not sure where to go as far as kalkwasser ect because the calciums about where it should be. currently-Cal 450, mag 1600, alk, 7.6 no N03 ( i'll get to figuring this out later)or p04 that shows up on tests. appx 70 gallon system. Only running a phospad and a skimmer in sump. I know I'm missing a few things as far as water chemistry is concerned but that's why I ready on here daily! Thanks!

Dom · Jun 8, 2016

I've recently been through some HEAVY schooling on reef chemistry and by no means am I an expert. But in an effort to help, I'd like to know what are your pH is and your Salinity readings? There are several possible causes for a drop in Alk. I understand that there is a relationship between Alk and pH. This is why I ask.

ngvu1 · Jun 8, 2016

Yup, I believe that. That is why I don't want any fast growing SPS any more

; Your alk will drop so fast and suddenly the SPS start to RTN/STN.....gone! If the alk level is not watched daily...

Caseyoidae · Jun 8, 2016

I lost a frag to rtn this morning!

Caseyoidae · Jun 8, 2016

Specific gravity is 1026 not sure what ph is?

Caseyoidae · Jun 8, 2016

so soda ash top off water?

Randy Holmes-Farley · Jun 9, 2016

1.4 dKH per day (your demand) is not very high, but it is fairly high for a single coral. Still, even coralline algae can consume 2-3 dKH per day.

So it is certainly possible the coral and other tank creatures are using that amount of alk.

There are lots of good ways to supplement calcium and alkalinity, and the best of them do both ion proper proportions to demand.

I discuss them here:

The Many Methods for Supplementing Calcium and Alkalinity - REEFEDITION
https://www.reef2reef.com/blog/the-many-methods-for-supplementing-calcium-and-alkalinity

Caseyoidae · Jun 9, 2016

Thanks! So should I strart with kalkwasser even though my calcium is already 450? Or make the correction with baking soda then begin kalkwasser regularly?

WetWhistle · Jun 9, 2016

I would make the correction with a buffer and not kalk. If you use kalk you will mess up your ratio and drive your calcium to high. Kalk is good for when you are maintaining calcium and DKH but should not be used for adjusting of calcium or DKH.

Caseyoidae · Jun 9, 2016

Thanks! I'll see what the Lfs has tonight

WetWhistle · Jun 9, 2016

I use Alkalin8.3-P by Brightwells.

Caseyoidae · Jun 9, 2016

Update. Added 20 mil of red seas part b buffer About an hour ago. Half the recommended dose for my tank. Had to frag the tip of an acro frag in hopes of saving it from rtn just now. Thanks for the help!!!!

Caseyoidae · Jun 9, 2016

just tested alk and it is now 8.1 !!!! Now I will just measure again tomorrow and figure out my exact consumption for daily dosing. Because I didn't do a before and after just now I can't be sure how low it actually went since the last test.it says on the bottle 1ml in 25 gallons = .1 dkh so I think I can get this ! Thanks again!

Randy Holmes-Farley · Jun 10, 2016

WetWhistle said:
I would make the correction with a buffer and not kalk. If you use kalk you will mess up your ratio and drive your calcium to high. Kalk is good for when you are maintaining calcium and DKH but should not be used for adjusting of calcium or DKH.

How would that happen?

A 2 dKH boost to alk using limewater will only boost calcium by 14 ppm, and will be adding approximately the amount of calcium that was consumed when the alk dropped by 2 dKH in the first place.

The big thing you cannot do is correct the other way around. A substantial boost to calcium (say, 50 ppm) would push alk way too high (boosting it by 7 dKH).