Kalk questions

[Hannahmunt]

Hello,

ive just ordered some kalk +2 from brightwell aquatics. Since adding a few sps to my tank my magnesium has been dropping a lot.

3 days ago my tests were

Ca 440
Dkh 10.8
Mg 1290
Ph 8

today after a 20% water change

ca 430
Dkh 10.2
Mg 1200
Ph 8

my questions are:

do I need to do multiple water changes to get to the desired readings and the. Start dosing?

i do 20% weekly water changes, will I still be able to do that or should I stop if I am now dosing?

I plan on dosing in a 500ml bottle on a drip, how much kalk should I add to that amount of water?

thanks

 

[Miami Reef]

How many gallons is your tank?


Limewater (Kalkwasser) is a balanced solution to maintain alkalinity and calcium. Your alkalinity is on the higher end, so there isn’t a need for dosing now IMO.


The magnesium test drop is likely a testing error. What salt mix do you use?

 

[Hannahmunt]

My tank is 40g

I use natural seawater.

I was advised to get kalk+2 to keep everything consistent.

should I just be dosing magnesium then rather than this?

 

[Pistondog]

Are you dosing anything else? Hard to understand that dkh with 20% natural sea water. Verify your dkh results at your local fish store.
You need to test alk daily and pick a target, between 7 and 9 dkh.
Dose nothing until the dkh is inside that range. Then dose your supplement to maintain that dkh. When you know your tanks alk consumption, you can test dkh weekly.

 

[Miami Reef]

My tank is 40g

I use natural seawater.

OK, that may explain why the magnesium, alkalinity, and calcium are dropping.

Here’s an excellent article to read: Optimal Parameters for a Coral Reef Aquarium: By Randy Holmes-Farley

 

[Hannahmunt]

Are you dosing anything else? Hard to understand that dkh with 20% natural sea water. Verify your dkh results at your local fish store.
You need to test alk daily and pick a target, between 7 and 9 dkh.
Dose nothing until the dkh is inside that range. Then dose your supplement to maintain that dkh. When you know your tanks alk consumption, you can test dkh weekly.

I only dose a nitrate remover, nothing else.

it used to be around 9 but last few months it’s been high.

 

[Aqua Man]

I use natural seawater.

What is the DKH of the natural seawater?

Most recommend keeping Alk close to the saltwater that you use for water change. More stable that way.

 

[Randy Holmes-Farley Verified Community Expert]

I was advised to get kalk+2 to keep everything consistent.

should I just be dosing magnesium then rather than this?

Yes, if you need magnesium, use a magnesum supplement.

You were advised wrong and should not take advice from whoever proposed that product. If it was an LFS selling it, shop elsewhere.

Sadly, Brightwell has a poor understanding of chemistry and that lack extends into their own product descriptions. Kalk+2 is a ridiculous product. It’s ok to use it, but just recognize it is not a useful source of magnesium. It actually has less magnesium in it (by Brightwell’s own claims) than the food grade material I was using (which is very little), and magnesium cannot dissolve into kalkwasser due to the high pH, precipitating magnesium hydroxide.