Low Alkalinity Reef Tank with Calcium Reactor

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FunaiReefSystems

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Have been experiencing low alkalinity with my sps dominant mixed reef tank. Any suggestions as to what I should do? I was wondering if it is possible the current calcium reactor is too small. The tank is a red sea 525XL (525 Liters) plus about 50 gallons of sump. Current alkalinity is 6.1 but pH is around 8, calcium is a little above 500. Ive been told to get the alkalinity in check and worry about the calcium later as it will fall into place but this seems risky...

Corals are doing great for the most part. I check all my parameters with Hanna measuring devices but just sent out a lab grade sample to be tested.
 
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FunaiReefSystems

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If the reactor is holding your alkalinity steady, it may be worth manually dosing a bit of 2-part to get the alk back to where you want it.
I did think of that. Wasn't sure if it was a good idea though. Any thoughts on the calcium reactor being too small?
 

Breadman03

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It is possible that it is too small, though I suspect it is fine. For example, this is a fairly small calcium reactor and is rated for tanks roughly your size with heavy stock. You likely just have to find the balance of pH and flow to match your demand.
 
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Randy Holmes-Farley

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We cannot judge whether it is too small without know how much flow through it, alk in the effluent, pH of the effluent, etc.

I would not assume you can make a one time boost to alk and get it to stay there. It takes more alk dosed every day to maintain 8 dKH than it does 6 dKH because demand rises as the alk rises.
 
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FunaiReefSystems

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Should I just add some alkalinity to the auto top off? Or ditch it completely and go to a doser although id hate to do this since my results are mind blowing...
 

Breadman03

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Personally, I would dose it independently for better control. You're only going to dose while getting your reactor adjusted to meet your demand.

We cannot judge whether it is too small without know:
how much flow through it?
alk in the effluent?
pH of the effluent?

Randy poses some good questions here. Answer those for some good guidance about your reactor.
 
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FunaiReefSystems

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yes, dial in the reactor to deliver the needed alkalinity and don't worry about the calcium.

What happens if you add more CO2 (lower the pH, if you control via pH)?
How do you recommend dialing in the reactor to raise the alkalinity? Are you saying just turn down how often the C02 is dosed through the reactor by turning the PH meter down? Also do you think changing out the media might be a good idea?
 
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Randy Holmes-Farley

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What I can't understand is why my pH levels are so solid if alkalinity is low...

Not sure what you mean by solid. At alk of 6, the pH of seawater in equiilibrium with air would be abotu the pH 8 you report. :)
 

Randy Holmes-Farley

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How do you recommend dialing in the reactor to raise the alkalinity? Are you saying just turn down how often the C02 is dosed through the reactor by turning the PH meter down? Also do you think changing out the media might be a good idea?

Let's back up.

How are you controlling it now?

It is critical to tune the reactor to the needs of your tank (based on alkalinity).

Lowering the pH inside the reactor by adding more CO2 will dissolve more media and deliver more alk and calcium to the tank.

Increasing the flow through the reactor while maintaining the same pH in the reactor (which requires more CO2 as well) will also dissolve more media.
 

melev

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Have you read my article on calcium reactors yet? http://www.melevsreef.com/articles/how-to-set-up-a-calcium-reactor

If the tank's current alkalinity isn't high enough, you need to melt more media to increase the dKH of the effluent. Have you measured the output of the reactor to see what the alkalinity measures? This should usually be somewhere between 19 and 35 dKH. If my alkalinity is low on my tank, I lower the pH within the calcium reactor to melt the media a tad more. Real world numbers: If the pH was 6.5 and alkalinity isn't high enough, I'll change it to 6.3 and measure the results the next day. Whatever change you make, usually you need to wait 24 hours before measuring the results.

The effluent's rate should be the same day in and day out. Don't let it slow down nor speed up, keep that one steady. I use a steady trickle; I don't drip it into my system. This is discussed in my article too.

This is why it takes a couple of weeks to dial in a calcium reactor. But no, I wouldn't dose anything supplemental as that just adds to the confusion.
 

jda

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Over the course of a year, my alk, calcium and mag numbers diverge a bit. I add some baking soda and lower the output of the CaRx to bring the calcium numbers down. I have no way to know this, but I think that the clams do not use it in balance like the acros do.

High alk and low calcium is easy since I can just change water with more muratic acid added to it.

Is there any way to lower calcium on fresh salt mix? ...similar to adding muratic acid for alk?

If you are worried about the media, then test the output of the effluent for both alk and calcium. You can just keep on using Salifert final-step syringes of "stuff" until the color changes and just add them up. If the output is way out of whack, then a media change might be good.
 

Randy Holmes-Farley

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Over the course of a year, my alk, calcium and mag numbers diverge a bit. I add some baking soda and lower the output of the CaRx to bring the calcium numbers down. I have no way to know this, but I think that the clams do not use it in balance like the acros do.

High alk and low calcium is easy since I can just change water with more muratic acid added to it.

Is there any way to lower calcium on fresh salt mix? ...similar to adding muratic acid for alk?

If you are worried about the media, then test the output of the effluent for both alk and calcium. You can just keep on using Salifert final-step syringes of "stuff" until the color changes and just add them up. If the output is way out of whack, then a media change might be good.

No, but you can use a low calcium mix, such as normal IO. That's what I did because limewater/kalkwasser adds very slightly too much calcium over time, relative to alkalinity. :)
 
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