Trouble getting alk and calcium where they need to be.

[Jeff Murray]

I have a 75 gallon tank and sump which has been up for over a year. Lots of rock in the sump and one big rock in tank. Tank bottom is coral tile. I have just a few soft corals and some gorgonians. Soft corals look good and are starting to spread. One bunch of white star polys which has never spread and looks pale. Its been in a year. I also have feather dusters, two haitian anemones and a flame scallop which are all doing fine for over 8 months. Fish population is light. 3 clowns, 2 cardinals, 1 harlequin bass. Few snails and hermits. I auto top off with 2 teaspoons of kalkwasser ( Kalk +2) per gallon. My pH is 8.2. Nitrates below .25 My Alkalinity however seem to stay at 12.5. Calcium at 300. I have been dosing vinegar at 10m twice a day, morning and evening. I also put a cup in with 10 gallons of top off water to activate leached out kalk. Top off uses about 1/2 to 3/4 gallon per day. I have good flow and turnover. 10 gallon water change weekly using Instant Ocean reef salt. Also after a year I am just starting to see some coraline algae growing in spots. Not a lot and I expected much more by this time. How can I safely get my alkalinity and calcium up and keep it there? I was under the impression the kalkwasser would do it. All water is IO/DI.

 

[Bayareareefer18]

You are trying to bring alk up from 12.5? Do you mean bring up ca?

 

[JCOLE]

Looking at your corals there is a possibility that they're not consuming a whole lot of alkalinity. Also I use reef crystals as well and fresh mixes have higher ALK so you may be raising alkalinity with the 10 gallon water changes weekly. Have you tested your salt mix to see where your alk is at before doing water changes?

 

[Randy Holmes-Farley Verified Community Expert]

First, note that the kalk+2 is not adding magnesium, so don't get fooled by the Brightwell misunderstanding of basic chemistry.

That said, limwater (the english word for the germ word kalkwasser) can often meet the demand, as it did in my tank for 20 years, but not always. It is limited by evaporation.

That also said, your problem is not lack of adequate limewater (as evidenced by the more than enough alkalinity, you might actually want to use less), but by either a lack of sufficient calcium, or perhaps more likely, a calcium test kit error.

You first should double check tyhe calcium somehow (same kit on new salt water, different kit, lfs, etc.).

Then, if calcium is actually that low, boost it with calcium chloride. Limewater cannot boost calcium as alk will go through the roof.

 

[Jeff Murray]

My mistake on wanting to get alk up. Meant to say down. Ill try some calcium chloride. Any advice as to how to use it? Would I benefit from using something like Seachem Complete to get magnesium?

 

[Randy Holmes-Farley Verified Community Expert]

My mistake on wanting to get alk up. Meant to say down. Ill try some calcium chloride. Any advice as to how to use it? Would I benefit from using something like Seachem Complete to get magnesium?

Just use calcium chloride. Any brand is likely fine, or a DIY.

That said, I don't see any reasonable way to get to the numbers your report using the ingredients you report, hence my expectation that the calcium is a test error and not real. Calcium cannot decline on its own without alkalinity being consumed.
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Super, super, low salinity of a starting salt mix followed by balanced calcium and alkalinity dosing is about all I can imagine to get there.

 

[Jeff Murray]

Thanks. I did retest and it looks more like 360 now. I tested ocean water ( I live in the Keys) and it is only 380.

 

[LadyTang2]

First, note that the kalk+2 is not adding magnesium, so don't get fooled by the Brightwell misunderstanding of basic chemistry.

That said, limwater (the english word for the germ word kalkwasser) can often meet the demand, as it did in my tank for 20 years, but not always. It is limited by evaporation.

That also said, your problem is not lack of adequate limewater (as evidenced by the more than enough alkalinity, you might actually want to use less), but by either a lack of sufficient calcium, or perhaps more likely, a calcium test kit error.

You first should double check tyhe calcium somehow (same kit on new salt water, different kit, lfs, etc.).

Then, if calcium is actually that low, boost it with calcium chloride. Limewater cannot boost calcium as alk will go through the roof.

Does kalk contribute more to alk than ca, or equally?

 

[Randy Holmes-Farley Verified Community Expert]

Does kalk contribute more to alk than ca, or equally?

2.8 dKH for each 20 ppm of calcium.

if you try to use it to boost calcium, alk may go through the roof.