Combining a calcium reactor with a kalkwasser reactor

[Garfield90]

Hi guys,
I'm setting up a +- 1000 gallon system, and I have a question for you about ca, kh and mg dosing.
I'll use a calcium reactor with ARM media and probably magnesium from Zeovit, but also a kalkwasser reactor, mainly for keeping pH high and po4 low.
I won't use the kalkwasser as a top off system, and my idea is to have the reactor connected with a Profilux system. When the pH is less than 8,2 (example) limewater will be added. If rises more than 8,3 (example), limewater won't be added.

Is this possible? Or do I need to use the kalkw reactor in a different way?

Thanks in advance!

[ReachTheSky]

Wouldn't that make your Calcium and Alkalinity levels unpredictable and hard to maintain? Just a thought.

[bertoni]

I think the changes in salinity would be more damaging than the changes in pH. Personally, I'd just let the ATO run with Kalk, but some people switch between Kalkwasser and plain RO/DI based on pH.

[rogergolf66]

I have done this before. Set the Kalk to dose less then Evaporation per day but always dosing the same amount of Kalk Daily. Then dial in calcium reactor. Based on demand.

U will also need a top off unit still to dose the little amount that the Kalk is not topping off enough

Roger

[Mekanic]

I'd ask Chingchai, he's running both on a 1000g+ system

[d3hree]

I will be running both, kalk through an ATO but the ATO is on a timer so only tops up during lights out. Calc reactor solenoid on a timer that will run during lights on.

[rogergolf66]

I will be running both, kalk through an ATO but the ATO is on a timer so only tops up during lights out. Calc reactor solenoid on a timer that will run during lights on.

Ok now I see a problem when cal reactor solenoid is off will u also turn effluent from cal reactor off at the same time? This would maintain the ph level in reactor and that's a must. That being said the end of the tube for the effluent will most likely clog of u turn it off. I see the goal and understand it but I think u leave the cal reactor on 24 /7 then just dose Kalk at night for ph increase I think ph will be fine with leaving cal reactor on and just dosing kalk at pm. As I said before u really need to control how much is topped off each night of the Kalk or maintain steady cal and alk will be a challenge.

[Garfield90]

I have done this before. Set the Kalk to dose less then Evaporation per day but always dosing the same amount of Kalk Daily. Then dial in calcium reactor. Based on demand.

U will also need a top off unit still to dose the little amount that the Kalk is not topping off enough

Roger

Roger, thank you. I actually have a 50 gallon top off aquarium, so top off is not a problem. The Kalkwasser reactor contains a maximum of 30 liters (like 7.5 gallons).
On what you say, I think the better is to achieve a optimum limewater dosage to maintain pH at my desired level, and then adjust the calcium reactor.

One question, I've never used a kalkwasser reactor before, how often do you need to add new limewater to the reactor, as the existing has been already added to the system?

Thank you in advance

[rogergolf66]

Well adding Kalk depends on how much water u run through it. Ph will tell u when hits low though and need to add more

[d3hree]

Ok now I see a problem when cal reactor solenoid is off will u also turn effluent from cal reactor off at the same time? This would maintain the ph level in reactor and that's a must. That being said the end of the tube for the effluent will most likely clog of u turn it off. I see the goal and understand it but I think u leave the cal reactor on 24 /7 then just dose Kalk at night for ph increase I think ph will be fine with leaving cal reactor on and just dosing kalk at pm. As I said before u really need to control how much is topped off each night of the Kalk or maintain steady cal and alk will be a challenge.

Yes I would control the effluent aswell. Its all a little pie in the sky until I get up and running, its an 8000ltr system with mangroves and algaes (possibly reverse lit) so maybe I wont have much of a ph swing. If I dont I wouldnt bother running kalk and will just keep the calc reactor running. I would only run kalk to offset a ph drop after lights out.

[rogergolf66]

Just remember it's more important to control alk and calcium stable then to keep a high ph

[disc1]

but also a kalkwasser reactor, mainly for keeping pH high and po4 low.

I've heard this a few times lately. Where are people getting the idea that kalk is going to lower their phosphate levels? I don't think that is true in the least.

[rogergolf66]

I think they get that from some people adding vinager to the Kalk?

[Steveb]

I've heard this a few times lately. Where are people getting the idea that kalk is going to lower their phosphate levels? I don't think that is true in the least.


My guess would be from here:

http://reefkeeping.com/issues/2006-09/rhf/index.php#10


Phosphate Reduction via Calcium Phosphate Precipitation
<hr align="left" color="#006699" size="1px" width="75%"> One mechanism for phosphate reduction in reef aquaria may simply be the precipitation of calcium phosphate, Ca₃(PO₄)₂. The water in many reef aquaria is supersaturated with respect to this material, as its equilibrium saturation concentration in normal seawater is only 0.002 ppm phosphate. As with CaCO₃, the precipitation of Ca₃(PO₄)₂ in seawater may be limited more by kinetic factors than by equilibrium factors, so it is impossible to say how much will precipitate under reef aquarium conditions (without, of course, somehow determining it experimentally). This precipitation may be especially likely where calcium and high pH additives (such as limewater) enter the aquarium water. The locally high pH converts much of the HPO₄^-- to PO₄^---. Combined with the locally high calcium level (also from the limewater), the locally high PO₄^--- level may push the supersaturation of Ca₃(PO₄)₂ to unstable levels, causing precipitation. If these calcium phosphate crystals are formed in the water column (e.g., if they form at the local area where limewater hits the aquarium water), then they may become coated with organics and be skimmed out of the aquarium.
Many reefkeepers accept the concept that adding limewater reduces phosphate levels. This may be true, but the mechanism remains to be demonstrated. Craig Bingman has done a variety of experiments related to this hypothesis, and has published them in the old Aquarium Frontiers magazine. While many aquarists may not care what the mechanism is, knowing how it occurs will help us understand the limits of this method, and how to best employ it.
One possible mechanism could be through calcium phosphate precipitation, as outlined above. A second mechanism for potential phosphate reduction when using high pH additives is the binding of phosphate to calcium carbonate surfaces (http://www.rsmas.miami.edu/groups/jmc/fla-bay/fbay.html). The absorption of phosphate from seawater onto aragonite is pH dependent, with the binding maximized at around pH 8.4 (http://www.rsmas.miami.edu/groups/jmc/fla-bay/pp-samples/master1/sld013.htm) and with less binding occurring at lower and higher pH values. Habib Sekha (owner of Salifert) has pointed out that limewater additions may lead to substantial precipitation of calcium carbonate in reef aquaria. This idea makes perfect sense. After all, it is certainly not the case that large numbers of reef aquaria exactly balance calcification needs by replacing all evaporated water with saturated limewater. And yet, many aquarists find that calcium and alkalinity levels are stable over long time periods with just that scenario. One way this can be true is if the excess calcium and alkalinity, which such additions typically add to the aquarium, are subsequently removed by precipitation of calcium carbonate (such as on heaters, pumps, sand, live rock, etc.). It is this ongoing precipitation of calcium carbonate, then, that may reduce the phosphate levels; phosphate binds to these growing surfaces and becomes part of the solid precipitate.
If the calcium carbonate crystal is static (not growing), then this process is reversible, and the aragonite can act as a reservoir for phosphate. This reservoir can inhibit the complete removal of excess phosphate from a reef aquarium that has experienced very high phosphate levels, and may permit algae to continue to thrive despite all external phosphate sources having been cut off. In such extreme cases, removal of the substrate may even be required.
If the calcium carbonate deposits are growing, then phosphate may become buried in the growing crystal, which can act as a sink for phosphate, at least until that CaCO₃ is somehow dissolved. Additionally, if these crystals are in the water column (e.g., if they form at the local area where limewater hits the aquarium water), then they may become coated with organics and be skimmed out of the aquarium.
If phosphate binds to calcium carbonate surfaces to a significant extent in reef aquaria, then this mechanism may be attained with other high pH additive systems (such as some of the two-part additives, including Recipe #1 (http://reefkeeping.com/issues/2006-02/rhf/index.php) of my DIY system). However, this potential precipitation of phosphate on growing calcium carbonate surfaces will not be as readily attained with low pH systems, such as those using calcium carbonate/carbon dioxide reactors or those where the pH is low due to excessive atmospheric carbon dioxide, because the low pH inhibits the precipitation of excess calcium and alkalinity as calcium carbonate (http://reefkeeping.com/issues/2002-04/rhf/feature/index.php), as well as inhibiting the binding of phosphate to calcium carbonate."

[disc1]

Thanks

[bertoni]

The other way it might reduce phosphate is by encouraging coral growth. :) Seems a stretch, though.