Alkalinity: Can't Seem to Decrease

[DiZASTiX]

Dr Holmes-Farley: In in diagramme below, I performed small water changes, followed by a 20% water change several hours ago, perhaps causing that last dip. I am testing using the Hanna tester.

I'm trying to get my Alkalinity to 12.5, as my corals are bleaching and I've removed all but one of the SPS and some of the other corals to a QT tank.

I double check every step of the procedure. I draw out the sample water using a manual pipette set to the calibrated amount for 10 mL, and then check the meniscus every time. I also make sure to thoroughly wipe each of the two cuvettes with a towel before placing into the Hanna tester. The RODI water I've tested to 0.

What could be the cause of this rising of Alkalinity? There are 5 frags left (mixed) and a decorator crab. Can they decrease alkalinity on their own?

Thank you for your advice.

 

[vic5hands]

I’m trying to get mine lower than that. Check your salt see what the parameters are.

 

[DiZASTiX]

I'm using the black bucket and mixing to 1.026 SG. Red Sea indicates that up to 12.5 dKH is okay, and I'm happy to use their recommendation.

 

[Greenstreet.1]

In fresh mix what is your Alk when you make it ?
Also do you roll the bucket before using it ? It is recommended to roll the bucket before so you can get a total mix of ingredients.

 

[Randy Holmes-Farley Verified Community Expert]

Did you test the new water?
Do you have artificial rock?
Are you topping off with tap water?
Are you feeding fish? With enough nutrients, I think the alk won’t hurt corals.

 

[DiZASTiX]

Yes, the water mixes to 11.7 dKH. I don't have artificial rock, but I do have one piece of MarinePure ceramic, which I use to raise up my skimmer to the right water level.

I'm tapping off with 0 TDS RODI.

I don't have any fish, but I can add some tomorrow.

It's a 40 gal water system.

 

[Fishfinder]

you can lower alk with water changes if the new water has the same alk

maybe I don't understand the question

 

[DiZASTiX]

The new water has an alkalinity of 11.7 dKH at 1.026 SG, while the current water has an alkalinity of 13.4 at 1.026 SG. Water changes have slightly depressed alkalinity, only to be met with raising alkalinity levels hours later--reasons unknown. The questions are:

1. Why is alkalinity going back up by itself?
2. What is the best way at this point to decrease alkalinity from 13.4 to 12.5?

 

[Fishfinder]

how big are your water changes?

 

[DiZASTiX]

I performed two 5% water changes followed by a 20% water change.

 

[Greenstreet.1]

How long do you let the new batch mix for before testing ?

 

[DiZASTiX]

I have test results over 24 hrs after mixed, as I'm using that water for QT.

 

[Greenstreet.1]

Since the Hanna is seeing the difference I can’t say try a next kit. All I can suggest is using rodi water to bring it where you want it.

 

[DiZASTiX]

That's just it: how come with every RODI water change, it seems some mysterious force within the aquarium is fighting back and altering the alkalinity? Isn't that strange?

 

[Fishfinder]

5% from 13 to 11 won't change alk much at all. You would have to change 50% to get to 12

 

[Fishfinder]

You should be doing 5% with 8 dkh water to see any change