How to correct? Alk slowly rising, Ca dropping with Kalk

TCoach

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Starting to get into SPS corals since I've gotten my Nitrates and Phosphate more or less under control. However, since I've added ~12 SPS/LPS corals in the last 2 weeks (mostly beginner SPS), I've noticed my Ca keeps dropping even though my Alk is high. Looking for how to correct this situation.

Originally, I was adding 6tsp of Kalk to my 5 gallon ATO, but after talking with my LFS, dropped it to 5tsp to try and lower Alk a bit. But since adding the corals, suddenly my Ca has dropped below 400ppm for 2 weeks now. What is the best way to correct this?

Just for info, I just picked up a 4 head dosing pump, so dosing via that can be an option. I am wanting to head that way and just use the ato for pure RO ato duties.

Thanks!

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Randy Holmes-Farley

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Kalkwasser isn't the cause of this imbalance. Generally, it actually adds a little more calcium than the balanced amount of alkalinity.

The alk is being boosted some other way, such as by dosing nitrate or declining nitrate, or top off with tap water containing alkalinity.

That said, it's fine to boost the calcium with calcium chloride, as needed.

This calculator shows how much:

 
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TCoach

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Kalkwasser isn't the cause of this imbalance. Generally, it actually adds a little more calcium than the balanced amount of alkalinity.

The alk is being boosted some other way, such as by dosing nitrate or declining nitrate, or top off with tap water containing alkalinity.

That said, it's fine to boost the calcium with calcium chloride, as needed.

This calculator shows how much:

I have a bio pellet reactor and GFO reactor running to help with Nitrate and Phosphate control. Other than that, just an in sump refugium with Chaeto growing.

So, are you suggesting that the bio pellets could be contributing to the Ca imbalance?
 

nereefpat

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Kalk will add alk and Ca at the correct ratio. Water changes and the salt mix and the values of a fresh batch of saltwater can skew things a bit.

To me, it looks like your alkalinity is steady. A good alk test kit, like Salifert, is still going to be +/- about 0.3 dKH.

The Ca test will also have some error, usually +/- about 20 ppm. What kit are you using for Ca?
That drop from 441 to 391 is pretty steep for 5 days. 50 ppm of Ca use would equate to about 7 dKH, plus you are dosing.

If it were me...I'd probably shut off the kalk for a few days, while letting the alk drift down a point or two. I would test Ca now, and then boost it with CaCl to get it where you want it. Then, when the values are where you want them, continue with the kalk.
 

Randy Holmes-Farley

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I have a bio pellet reactor and GFO reactor running to help with Nitrate and Phosphate control. Other than that, just an in sump refugium with Chaeto growing.

So, are you suggesting that the bio pellets could be contributing to the Ca imbalance?

Any decline in nitrate (except by water change) will add alkalinity.
 
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TCoach

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Kalk will add alk and Ca at the correct ratio. Water changes and the salt mix and the values of a fresh batch of saltwater can skew things a bit.

To me, it looks like your alkalinity is steady. A good alk test kit, like Salifert, is still going to be +/- about 0.3 dKH.

The Ca test will also have some error, usually +/- about 20 ppm. What kit are you using for Ca?
That drop from 441 to 391 is pretty steep for 5 days. 50 ppm of Ca use would equate to about 7 dKH, plus you are dosing.

If it were me...I'd probably shut off the kalk for a few days, while letting the alk drift down a point or two. I would test Ca now, and then boost it with CaCl to get it where you want it. Then, when the values are where you want them, continue with the kalk.
I'm using Hanna checkers for Alk/Ca/Nitrate/Phosphate

I did just refill my ATO jug today and just used RODI. There was maybe an inch of water in there with Kalk, but mostly just plain ro this time. I'm wanting to figure out the Ca/Alk usage so I can dose straight Kalk in the near future.
 

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Unless your calcium is completely off balance 300ppm or so - I would not worry about it too much. Alk is far more important, as Randy suggested - you can do small corrections to Calcium using calcium chloride, but again - alk stability is far more important.
 
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Ok, as part of a test to burn in my new Jebao DP-4, I put 3 TBS of Seachem Reef Advantage Calcium in ~1 gal of RODI and am dosing 50ml/hr to slowly bring up the calcium to closer to 420ppm. (Calculator said 9.3 tsp) Do you think this is 2 fast? It should take 1.5-2 days to dose the solution and go from 371 - ~420.

I'm testing Ca and Alk daily to try and determine my consumption and then my plan is to dose saturated kalk to meet the tanks demand with my new doser.
 

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Ok, as part of a test to burn in my new Jebao DP-4, I put 3 TBS of Seachem Reef Advantage Calcium in ~1 gal of RODI and am dosing 50ml/hr to slowly bring up the calcium to closer to 420ppm. (Calculator said 9.3 tsp) Do you think this is 2 fast? It should take 1.5-2 days to dose the solution and go from 371 - ~420.

I'm testing Ca and Alk daily to try and determine my consumption and then my plan is to dose saturated kalk to meet the tanks demand with my new doser.
Normally for me the rule of thump for things like calcium and potassium corrections - 10ppt a day maximum.. your speed should not cause problems - but I don't see a reason why you would rush? Bring it from 370 to 420 over a couple of weeks...
 

Randy Holmes-Farley

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Ok, as part of a test to burn in my new Jebao DP-4, I put 3 TBS of Seachem Reef Advantage Calcium in ~1 gal of RODI and am dosing 50ml/hr to slowly bring up the calcium to closer to 420ppm. (Calculator said 9.3 tsp) Do you think this is 2 fast? It should take 1.5-2 days to dose the solution and go from 371 - ~420.

I'm testing Ca and Alk daily to try and determine my consumption and then my plan is to dose saturated kalk to meet the tanks demand with my new doser.

I generally do not think that the rate of calcium rise to normal levels is any concern, except if there are impurities in it, in which case, slower is better.

IMO, 2 days is fine to go from 370 to 420 ppm with a quality material.
 
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TCoach

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Normally for me the rule of thump for things like calcium and potassium corrections - 10ppt a day maximum.. your speed should not cause problems - but I don't see a reason why you would rush? Bring it from 370 to 420 over a couple of weeks...
I think it is me getting use to the volumetric measurements. Before I've either used my ATO or a drip line, so no real concept of how much I was dosing.

I just reset it to 25ml/hr to slow things down. Keep trying to remember that "Fast is slow and SLOW is fast in reefing"! :D
 
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