Kalk dosing problem

[bmk]

Hi
I started dosing Kalk on the 28th June, with 2 tsp per gallon with my ATO, I manually dose mag to keep it up to around 1350. All went well but it does not evaporate a lot of water (approx 10L a week) but the kalk kept the cal at 420 and alk 9dkh so I was happy.
Last weekend I bought a fan to aid in evaporation, I placed the fan so it pointed across the surface and all seemed ok. last night my partner who looks after the tank while I work away stated that the tank has used half of the top off water (around 12L), which is great after 4 days so I asked her to test, these are the results, cal 370, kh 9.6dkh. Why has the calcium dropped so much considering the tank used twice the amount of Kalk in 4 days.

Many thanks for any advice.

Barry

 

[Playa-1]

It's hard to say. Has anything changed in the tank recently?
New corals? My first intuition would be testing error.

 

[bmk]

Hi
No new corals, the only thing other than the fan and the fact it used twice the amount of Kalk due to greater evaporation is that I put a small bag (2 cup fulls) of crushed coral in the tank to 'seed it' for my new quarantine tank which I am setting up this weekend, surely this hasn't 'soaked up' extra calcium.

Barry

 

[HaywoodJafragit]

More evaporation, therefore more kalk but less Calcium? this doesn't add up. Your Magnesium could be low, otherwise if nothing have changed in the tank there must have been an error reading the test kits like Playa-1 said.

Personally I cannot keep Ca by dosing Kalkwasser only. I have been adding Calcium Chlorhide regularly plus kalk with the top-off to keep Alkalinity up and even so, sometimes I have to add baking soda to keep it around 3 meq/L, my system only evaporates 1 gallon a day and I have a few SPSs. I'm saving money to buy a calcium reactor right now.

 

[bmk]

The mag is dosed 3 x a week with Seachem Reef Advantage magnesium, alk is dosed 2 x week if needed with Seachem Reef Builder. Currently mag 1350, alk 9.6 dkh
My partner tested twice last night for cal/alk and got the same readings using Salifert test kits, she has been doing the testing of all parameters for the last 16 months with no problems. I only have 2 candy cane, 1 acropora, 1 turbinaria and 1 hammer, these corals are only small that is way I thought kalk would be sufficient, and it has been for the last 3 weeks, just this week when more was added due to better evaporation, as I stated above it couldn't be the small bag of sand 'soaking' it up?

Barry

 

[bmk]

Bump

 

[Sk8r]

Kalk cannot raise calcium or alk on its own (much). You need to set those levels by dosing, and then adequate evaporation will keep up with it.

Also, even with kalk, alk and cal will drop like a stone if you are short of magnesium. Mag should be 3x the level of calcium you set by dosing.

 

[bmk]

Thanks Sk8r, mag is dosed 3 x week with Seachem Advantage magnesium and is currently 1350, alk is dosed when needed has been around 9 dkh for the last 3 weeks, the only thing we didnt have to dose was cal as the Kalk kept up with it for the last 3 weeks, it only started when we got the fan last weekend and it evaporated double in 4 days adding more Kalk.

Barry

 

[Playa-1]

You sure are dosing lots of Mag. I hardly ever have to dose it.
What type of Salt Mix are you using and how often are you doing water changes?

 

[bmk]

Hi
Salt is Red Sea Coral Pro made with RO/DI, water change is 15% every 3 weeks. I dose 2 tsp Seachem Mag every mon/wed/fri and that gives me around 1350.

Barry

 

[Playa-1]

I think I've dosed Mag once in the last 6 months.

 

[bmk]

If I dont dose the mag goes down to around the 1100/1150 mark after a week, testing is with a Salifert test kit and has always been like this.

Barry