Kalk Dosing vs 3 Part - build up?

FlyPenFly

SPS Killer
I've been debating for a second tank whether to use a kalk reactor or 3 part.

I currently use 3 part in my SPS heavy reef. I expect this second tank to also be very SPS heavy.

As far as I remember, the advantages to a kalk reactor being used is that it simplifies what you need to buy or make and it increases PH. It also seems like if you do less water changes, you prevent the build up of sulfates and chloride ions.

With a high alk demand, let's say 1mg per 1g, how much of a problem would a kalk reactor have keeping up with that?
 

Randy Holmes-Farley

Reef Chemist
Premium Member
A good two/three part raises salinity, but that's the only concern. It can raise pH.

Limewater won't add magnesium, but does raise pH the most and doesn't increase salinity.

Both are good ways to go. :)
 

FlyPenFly

SPS Killer
Thanks Randy.

Do you think I'd see more build up on my pumps from Kalk or 2 part?

Essentially I'm debating between buying a $500 doser or $250 Reef Octo kalk reactor. I have a BRS 1.1ml doser I can run on my apex for dosing kalk.
 

Jimmy54

New member
The higher pH - the more chance of build up on your pumps.
But partially it also depends on the concentration magnesium and bicarbonates
(or carbonates - because that's where a percentage of bicarbonate is converted into when pH increases)
Magnesium forms soluble ion-pairs with a small percentage of carbonate and remains soluble a little longer than calcium carbonate.
EDIT: maybe I should say a small percentage of magnesium forms soluble ion-pairs with carbonate.

Just curious; how does 1 mg (per 1 g) relate to alk ?
 
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Randy Holmes-Farley

Reef Chemist
Premium Member
As mentioned, and with everything else being the same, limewater will result in a higher tank pH and so cause more precipitation. That assumes the two part is also dosed similarly slowly as the limewater, which is often not the case. Once or twice a day dosing with a two part could cause as much precipitation as slow dosing of limewater due to the pH boosts that each dose gives (assuming you are using a high pH two part and not a bicarbonate based two part).. :)
 

FlyPenFly

SPS Killer
Interesting, in my SPS tank, I dose on a staggered schedule 5 times a day.

I think I might just try the kalk reactor out and use a similar 5 times a day schedule. I don't see a real benefit to using a 2 part doser if something that costs half as much will do the job.
 

bertoni

Premium Member
Kalk is very dilute, so it might not be able to meet the demands of your system, but it is cheap and reasonably easy to dose. I'd give it a try, personally.
 

madadi

ReefOG
I personally use both and has worked for me. Kalk will only provide so much calcium and alk so eventually you might need a second option in a heavily stocked SPS tank.
 
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